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The rapid advancement of technology over the past decade has resulted in significant transformations within the photography sector. In photographic processes, photosensitive materials are used by photographers to convert latent images into visible ones. Among other photographic developers, Metol has been used as a monochrome photographic chemical for more than 100 years in Europe. Metol (MTL), chemically N-methyl-p-aminophenol sulphate with formula [HOC6H4NH2(CH3)]2SO4, is also used as a corrosion inhibitor, antioxidant, and antimicrobial, and it serves as an intermediary for the medication diloxanide and dyes for fur and hair [1]. Since it is used in the photographic industry, it is released into the water, contaminating ground, and household water. It can be easily found in different water bodies such as rivers, lakes, ponds, and seas. MTL was found to be a cancerogenic organic pollutant with a significant impact on human health, the environment, animals, plants, and water sources [2]. MTL is non-biodegradable and can accumulate in biotic organisms. It is also related to numerous environmental issues, even in low concentrations. Nevertheless, a larger dose of MTL is necessary to have a substantial effect on several health problems, such as cancer, irritable eyes, slowed heartbeat, skin allergies, and harm to the body's internal blood supply [3]. Therefore, developing a straightforward, quick, affordable, sensitive, and practical method for ML detection in aquatic bodies is imperative. In this study, a susceptible and selective sensor for the detection and quantification of nitrogen-organic pollutant Metol (MTL) was developed. For this purpose, samarium-molybdate (Sm2(MoO4)3 nanoparticles were synthesized by organic solvent-free, eco-friendly, low-cost hydrothermal method and used as an excellent modifier with high catalytic efficiency for implementation into the carbon paste. Electrochemical measurements indicate that the developed electrode facilitates electron t

The nucleation, crystallization, and growth mechanisms of MnFe2O4, CoFe2O4, NiFe2O4, and ZnFe2O4 nanocrystallites prepared from coprecipitated transition metal (TM) hydroxide precursors treated at sub-, near-, and supercritical hydrothermal conditions have been studied by in situ X-ray total scattering (TS) with pair distribution function (PDF) analysis, and in situ synchrotron powder X-ray diffraction (PXRD) with Rietveld analysis. The in situ TS experiments were carried out on 0.6 M TM hydroxide precursors prepared from aqueous metal chloride solutions using 24.5% NH4OH as the precipitating base. The PDF analysis reveals equivalent nucleation processes for the four spinel ferrite compounds under the studied hydrothermal conditions, where the TMs form edge-sharing octahedrally coordinated hydroxide units (monomers/dimers and in some cases trimers) in the aqueous precursor, which upon hydrothermal treatment nucleate through linking by tetrahedrally coordinated TMs. The in situ PXRD experiments were carried out on 1.2 M TM hydroxide precursors prepared from aqueous metal nitrate solutions using 16 M NaOH as the precipitating base. The crystallization and growth of the nanocrystallites were found to progress via different processes depending on the specific TMs and synthesis temperatures. The PXRD data show that MnFe2O4 and CoFe2O4 nanocrystallites rapidly grow (typically <1 min) to equilibrium sizes of 20-25 nm and 10-12 nm, respectively, regardless of applied temperature in the 170-420 °C range, indicating limited possibility of targeted size control. However, varying the reaction time (0-30 min) and temperature (150-400 °C) allows different sizes to be obtained for NiFe2O4 (3-30 nm) and ZnFe2O4 (3-12 nm) nanocrystallites. The mechanisms controlling the crystallization and gro

The nucleation, crystallization, and growth mechanisms of MnFe2O4, CoFe2O4, NiFe2O4, and ZnFe2O4 nanocrystallites prepared from coprecipitated transition metal (TM) hydroxide precursors treated at sub-, near-, and supercritical hydrothermal conditions have been studied by in situ X-ray total scattering (TS) with pair distribution function (PDF) analysis, and in situ synchrotron powder X-ray diffraction (PXRD) with Rietveld analysis. The in situ TS experiments were carried out on 0.6 M TM hydroxide precursors prepared from aqueous metal chloride solutions using 24.5% NH4OH as the precipitating base. The PDF analysis reveals equivalent nucleation processes for the four spinel ferrite compounds under the studied hydrothermal conditions, where the TMs form edge-sharing octahedrally coordinated hydroxide units (monomers/dimers and in some cases trimers) in the aqueous precursor, which upon hydrothermal treatment nucleate through linking by tetrahedrally coordinated TMs. The in situ PXRD experiments were carried out on 1.2 M TM hydroxide precursors prepared from aqueous metal nitrate solutions using 16 M NaOH as the precipitating base. The crystallization and growth of the nanocrystallites were found to progress via different processes depending on the specific TMs and synthesis temperatures. The PXRD data show that MnFe2O4 and CoFe2O4 nanocrystallites rapidly grow (typically <1 min) to equilibrium sizes of 20-25 nm and 10-12 nm, respectively, regardless of applied temperature in the 170-420 °C range, indicating limited possibility of targeted size control. However, varying the reaction time (0-30 min) and temperature (150-400 °C) allows different sizes to be obtained for NiFe2O4 (3-30 nm) and ZnFe2O4 (3-12 nm) nanocrystallites. The mechanisms controlling the crystallization and gro

Hydroxyapatite is a biocompatible material with various applications. To meet the demand for industrial use of this material, a rapid and upscalable process for the synthesis of hydroxyapatite nanoparticles was developed using an in-house developed two-stage continuous flow hydrothermal reactor. In the framework of this study, phase pure and highly crystalline 30 to 115 nm long hydroxyapatite nanorods were produced for potential use as nanofertilizers. The phase composition of the nanorods was confirmed by X-ray diffraction. Particle size and shape were investigated using transmission electron microscopy. Inductively coupled plasma mass spectrometry was used to determine the Ca:P ratio. It was shown that the use of a second mixing stage allows the particle length to be decreased down to 30 nm without compromising on crystallinity. In addition to using different mixing stages, adjusting the pH and controlling the flow speed allow wide range size tuning of the produced particles. The experimental setup allows for continuous synthesis of phase pure and highly crystalline hydroxyapatite nanorods, ensuring the reproducibility and scalability of the process. Dispersive behavior and dissolution in citrate buffer at a hydroponic pH of 5.5 were studied to evaluate further possibilities of applying produced NPs on the plants.

This study aims to analyze the influence of process parameters used for hydrothermal synthesis of CaP coatings on their properties and to improve their corrosion resistance and biocompatibility compared to the substrat AZ31. The parameters monitored were deposition time, pH of the reaction mixture, and concentration of precursors in the reaction mixture. For the deposited CaP coatings on AZ31 magnesium alloy, the surface morphology and the number of structural defects were evaluated using scanning electron microscopy. Electrochemical corrosion properties were evaluated using polarization techniques in Hank’s solution. The results showed that the best properties were obtained for the sample prepared in a reaction mixture at 120 °C, pH 5 for a deposition time of 120 min, when the concentration of precursors in the reaction mixture was 0.30 mol/l Ca(NO3)2·4H2O and 0.28 mol/l NH4H2PO4. Under these conditions, the best electrochemical corrosion properties were achieved.

In the eruptive event of Tajogaite (2021) in La Palma, Canary Islands, large quantities of volcanic ash were accumulated, affecting the local environment and urban areas. In this study, volcanic ash sampled from urban areas (catalogued as municipal waste (20 03 03) by the European Wastes Catalogue) were converted into zeolites by hydrothermal synthesis at 100 °C with previous alkaline fusion at 550 °C with distilled water. During this process, new phases of zeolite principally type X and sodalite have been identified by XRD at 2 h of incubation. These zeolites, with the course of incubation time, present competitive processes where the transformation into sodalite develops after 24 h as the predominant phase. The synthesized zeolitic material presents a high concentration as impurities in Fe2O3 (13.70 wt%), Na2O (12.70 wt%), CaO (11.65 wt%), and TiO2 (3.89 wt%) coming from the volcanic ash and NaOH introduced in the synthesis methodology. These impurities impart different physicochemical capabilities to the zeolitic material. The application of zeolites obtained in a preliminary fluoride adsorption experiment with volcanic leachate water rich in fluoride has been tested in a novel way. Removal efficiencies of 41.4% at acidic pH (5.77) have been obtained with 2 g L−1 adsorbent zeolitic material doses. A value-added material is obtained and applied in a preliminary way to solve a problem generated by the volcanic ash itself, allowing the End of Waste status and meeting different objectives of the sustainable development goals of the UN Agenda 2030., Ministerio de Ciencia e Innovación, Ministerio de Trabajo y Economía Social, Universidad Complutense de Madrid, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The development of new materials of interest in the bioimaging field is a relevant topic in current research. We present and study here novel non-covered and silica-covered Y0.9Tm0.1-xYbxVO4 samples with x = 0, 0.01, 0.05 and 0.09 that were prepared by hydrothermal synthesis. For comparison purposes, the study of Y0.9Tm0.1VO4 sample synthesized by the sol-gel method was also included. The relationships between the synthesis method, dopant content and luminescence emission were systematically studied by X-ray diffraction (XRD), FTIR spectroscopy and transmission electron microscopy (TEM). XRD profiles and FTIR spectra confirm the zircon-type structure of the obtained samples. Particles of two different morphologies were found in TEM images of uncoated samples, some spherical with sizes between 42 and 50 nm and others elongated. A shell thickness between 8 and 13 nm was also observed in silica-covered samples. Photoluminescence studies of our samples revealed emission in the NIR and visible ranges. Under excitation at 790 nm, the spectra of thulium-doped samples showed the characteristic emission band of Tm3+ ions. Substitution of thulium by ytterbium successfully led to an up-conversion emission under excitation at 980 nm. Finally, the fluorescent emission study in the NIR of samples that could be more biocompatible demonstrated that they are suitable for use as luminescent thermometers in the physiological temperature range., Ministerio de Ciencia, Innovación y Universidades (España), Instituto de Salud Carlos III, Comunidad de Madrid, Universidad Autónoma de Madrid, European Commission, Depto. de Química Inorgánica, Depto. de Química Física, Fac. de Ciencias Químicas, TRUE, pub

Water pollution by toxic dyes is an environmental problem that threatens human health. A green technology to solve this problem is the use of highly efficient photocatalysts under visible/solar light to degrade these organic molecules. However, develop affordable photocatalytic particles with high luminescence performance, enhanced stability, and low degradation is still a challenge. Here, it is reported the hydrothermal synthesis of an advanced and cost-effective nanocomposite based on a ceramic, cadmium sulphide, covered by silver nanoparticles (CdS/Ag), with outstanding photocatalytic efficiency for toxic dyes degradation under ultraviolet and direct solar light. The CdS/Ag nanocomposite completely degrade the Reactive Red 120 (RR 120), Acid Black 1 (AB 1) and Direct Blue 15 (DB 15) dyes in both light irradiations. Without scavenger, about 93% of degradation was observed at 75 min, remaining a high stability (more than 90%) after fourth degradation cycles.

Stable, water-soluble titanium complexed with mandelic acid was used as a precursor for titanium phosphorus double oxide obtained in hydrothermal conditions in the presence of phosphoric acid. Surprisingly, hydrolysis of organic complexes provided a microstructured sphere with narrow size distribution, low aggregation and a small fraction of morphological irregularities. Obtained microspheres had a complex structure comprised of flakes, whose size could be manipulated with temperature conditions. Samples were found to be electrochemically active against sulcotrione, a well-recognized herbicide. Electrochemical sensors based on the synthesized microspheres were successfully adapted for natural water reservoir analysis and exhibited low levels of detection of 0.61 µM, limit of quantification of 1.86 µM, wide dynamic linear range from 2 to 200 µM, good selectivity, excellent reproducibility and in-time stability.

Despite great attention toward transition metal tellurates especially M₃TeO₆ (M = transition metal) in magnetoelectric applications, control on single phasic morphology-oriented growth of these tellurates at the nanoscale is still missing. Herein, a hydrothermal synthesis is performed to synthesize single-phased nanocrystals of two metal tellurates, i.e., Ni₃TeO₆ (NTO with average particle size ∼37 nm) and Cu₃TeO₆ (CTO ∼ 140 nm), using NaOH as an additive. This method favors the synthesis of pure NTO and CTO nanoparticles without the incorporation of Na at pH = 7 in MTO crystal structures such as Na₂M₂TeO₆, as it happens in conventional synthesis approaches such as solid-state reaction and/or coprecipitation. Systematic characterization techniques utilizing in-house and synchrotron-based characterization methods for the morphological, structural, electronic, magnetic, and photoconductivity properties of nanomaterials showed the absence of Na in individual particulate single-phase MTO nanocrystals. Prepared MTO nanocrystals also exhibit slightly higher antiferromagnetic interactions (e.g., TN-NTO = 57 K and TN-CTO = 68 K) compared to previously reported MTO single crystals. Interestingly, NTO and CTO show not only a semiconducting nature but also photoconductivity. The proposed design scheme opens the door to any metal tellurates for controllable synthesis toward different applications. Moreover, the photoconductivity results of MTO nanomaterials prepared serve as a preliminary proof of concept for potential application as photodetectors.

This study aims to analyze the influence of process parameters used for hydrothermal synthesis of CaP coatings on their properties and to improve their corrosion resistance and biocompatibility compared to the substrat AZ31. The parameters monitored were deposition time, pH of the reaction mixture, and concentration of precursors in the reaction mixture. For the deposited CaP coatings on AZ31 magnesium alloy, the surface morphology and the number of structural defects were evaluated using scanning electron microscopy. Electrochemical corrosion properties were evaluated using polarization techniques in Hank’s solution. The results showed that the best properties were obtained for the sample prepared in a reaction mixture at 120 °C, pH 5 for a deposition time of 120 min, when the concentration of precursors in the reaction mixture was 0.30 mol/l Ca(NO3)2·4H2O and 0.28 mol/l NH4H2PO4. Under these conditions, the best electrochemical corrosion properties were achieved.

This study aims to analyze the influence of process parameters used for hydrothermal synthesis of CaP coatings on their properties and to improve their corrosion resistance and biocompatibility compared to the substrat AZ31. The parameters monitored were deposition time, pH of the reaction mixture, and concentration of precursors in the reaction mixture. For the deposited CaP coatings on AZ31 magnesium alloy, the surface morphology and the number of structural defects were evaluated using scanning electron microscopy. Electrochemical corrosion properties were evaluated using polarization techniques in Hank’s solution. The results showed that the best properties were obtained for the sample prepared in a reaction mixture at 120 °C, pH 5 for a deposition time of 120 min, when the concentration of precursors in the reaction mixture was 0.30 mol/l Ca(NO3)2·4H2O and 0.28 mol/l NH4H2PO4. Under these conditions, the best electrochemical corrosion properties were achieved.

The world’s increasing demand for energy and supplying this energy dominantlyfrom fossil fuels has a major impact on global climate change. Theenergy crisis has gotten more alarming in the recent years which increasedthe motivation for replacing fossil fuels with greener routes for energy harvest.There are various technologies developed for harvesting energy, andthe ability to recover energy from waste heat at a wide range of temperatures (from room temperature to more than 1000 ∘C) distinguished thethermoelectric (TE) materials from the rest. The drawback about the thermoelectricdevices is that they are too inefficient to be cost-effective in manyapplications, and the developments in nanotechnology is providing somesolutions to increase the efficiency of these materials and devices. The field of thermoelectrics suffer from large discrepancy of theresults in the literature, which is generally attributed to the variations inthe materials qualities, urging a need for the development of synthetictechniques that can lead to large-scale TE materials in reasonable timeframe. In this thesis, three different routes for rapid, scalable, and energyefficient, wet-chemical synthetic techniques for bismuth chalcogenidecompounds are presented. Microwave assisted heating during reactionprovided better control over the particle properties while reducing thereaction time and carbon footprint of the synthetic method, leading tomaterials bismuth chalcogenides with promising TE transport propertiesin a scalable and reproducible manner. Hybrid TE materials, and recently emerging solid-liquid TE materialsconcept, requires fabrication of porous TE films, to study the effect of variousinterfaces, including solid and liquid electrolytes. For this purpose, wedeveloped and optimized the electrophoretic deposition (EPD) process toprepare nanostructured porous TE films by preserving the size and morphologyof the as-synthesized bismuth chalcogenide particles. A new glass based substrate is desig, Världens ökande efterfrågan på energi och att tillhandahålla denna energifrämst från fossila bränslen har en betydande inverkan på den globalaklimatförändringen. Energikrisen har blivit allt mer alarmerande de senasteåren, vilket har ökat motivationen att ersätta fossila bränslen med grönaenergilösningar. Det har utvecklats olika tekniker för energiutvinning, menförmågan att återvinna energi från spillvärme vid ett brett temperaturintervall(från rumstemperatur till över 1000 °C) skiljer termoelektriska (TE)material från övriga. Nackdelen med TE-enheter är att de är för ineffektivaför att vara kostnadseffektiva i många tillämpningar, där utvecklingen inomnanoteknik erbjuder vissa lösningar för att öka effektiviteten hos dessamaterial och enheter. Inom området för TE-material finns det stora avvikelser i resultaten i litteraturen,vilket i allmänhet tillskrivs variationer i materialkvaliteten. Detfinns ett behov av att utveckla syntetiska tekniker som kan leda till högeffektivaTE-material i storskalig produktion på rimlig tid. I denna avhandlingpresenteras tre olika metoder för snabb, skalbar och energieffektiv våtkemisksyntetisering av bismutkalkogenidföreningar. Mikrovågsassisteraduppvärmning under reaktionen gav bättre kontroll över partikelegenskapernasamtidigt som reaktionstiden och koldioxidavtrycket för den syntetiskametoden minskade, vilket resulterade i bismutkalkogenider med lovandeTE-transportegenskaper på ett skalbart och reproducerbart sätt. Hybrida TE-material och det nyligen framkomna konceptet med fastvätska-TE-material kräver framställning av porösa TE-filmer för att studeraeffekten av olika gränssnitt, inklusive fasta och flytande elektrolyter. Fördetta ändamål har vi utvecklat och optimerat elektroforesdepositionsprocessen(EPD) för att framställa nanostrukturerade porösa TE-filmer genomatt bevara storlek och morfologi hos de syntetiserade bismutkalkogenidpartiklarna. En ett nytt substrat baserat på glas har designats och tillverkats föratt studera de, QC 2023-08-21

Most underground nuclear waste disposal concepts envisage the extensive use of cementitious materials in the geo-engineered barrier as a buffer and borehole sealing material and to ensure the mechanical stability of disposal systems. In order to assess the radionuclide (RN) retention potential of these barrier materials, it is necessary to study the impact of various repository relevant conditions that will evolve over time, such as changed pH values, increased ionic strength, elevated temperatures, or the release of organic components. The U(VI) retention by calcium (aluminate) silicate hydrate (C-(A-)S-H) phases, forming owing to Al-rich additives in cement formulations, was studied for samples with C/S molar ratios of 0.8, 1.2, and 1.6, representing different alteration stages of concrete, and with increasing A/S molar ratios of 0, 0.06, and 0.18 in each series, with special focus on the presence of organics. The latter thereby comprise gluconate (GLU), 2-phosphonobutane-1,2,4,-tricarboxylate (PBTC), and a mixture of cellulose degradation products (CDP) obtained from dry radiolysis (dose rate 0.6 kGy/h, absorbed dose ~ 1.37 MGy) followed by hydrolysis in artificial cement water (pH > 13, anoxic conditions) provided by project partners within the CORI framework. Complementary analytical techniques were applied to address the different specific aspects of the cement / organics / RN ternary systems. 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (XRD) were applied to determine the bulk structure and composition of the synthesized C-(A-)S-H phases. 13C-, and in case of PBTC also 31P-, MAS NMR measurements aimed at localization and speciation of the organic components involved [1]. 1H and 31P solution NMR of the aqueous phase allowed for quantification of the organics’ fraction removed from solution and hence associated with the solid phase. Retained U(VI) species were identified by time-resolved las

Water pollution by toxic dyes is an environmental problem that threatens human health. A green technology to solve this problem is the use of highly efficient photocatalysts under visible/solar light to degrade these organic molecules. However, develop affordable photocatalytic particles with high luminescence performance, enhanced stability, and low degradation is still a challenge. Here, it is reported the hydrothermal synthesis of an advanced and cost-effective nanocomposite based on a ceramic, cadmium sulphide, covered by silver nanoparticles (CdS/Ag), with outstanding photocatalytic efficiency for toxic dyes degradation under ultraviolet and direct solar light. The CdS/Ag nanocomposite completely degrade the Reactive Red 120 (RR 120), Acid Black 1 (AB 1) and Direct Blue 15 (DB 15) dyes in both light irradiations. Without scavenger, about 93% of degradation was observed at 75 min, remaining a high stability (more than 90%) after fourth degradation cycles.

This study aims to analyze the influence of process parameters used for hydrothermal synthesis of CaP coatings on their properties and to improve their corrosion resistance and biocompatibility compared to the substrat AZ31. The parameters monitored were deposition time, pH of the reaction mixture, and concentration of precursors in the reaction mixture. For the deposited CaP coatings on AZ31 magnesium alloy, the surface morphology and the number of structural defects were evaluated using scanning electron microscopy. Electrochemical corrosion properties were evaluated using polarization techniques in Hank’s solution. The results showed that the best properties were obtained for the sample prepared in a reaction mixture at 120 °C, pH 5 for a deposition time of 120 min, when the concentration of precursors in the reaction mixture was 0.30 mol/l Ca(NO3)2·4H2O and 0.28 mol/l NH4H2PO4. Under these conditions, the best electrochemical corrosion properties were achieved.

Water pollution by toxic dyes is an environmental problem that threatens human health. A green technology to solve this problem is the use of highly efficient photocatalysts under visible/solar light to degrade these organic molecules. However, develop affordable photocatalytic particles with high luminescence performance, enhanced stability, and low degradation is still a challenge. Here, it is reported the hydrothermal synthesis of an advanced and cost-effective nanocomposite based on a ceramic, cadmium sulphide, covered by silver nanoparticles (CdS/Ag), with outstanding photocatalytic efficiency for toxic dyes degradation under ultraviolet and direct solar light. The CdS/Ag nanocomposite completely degrade the Reactive Red 120 (RR 120), Acid Black 1 (AB 1) and Direct Blue 15 (DB 15) dyes in both light irradiations. Without scavenger, about 93% of degradation was observed at 75 min, remaining a high stability (more than 90%) after fourth degradation cycles.

Most underground nuclear waste disposal concepts envisage the extensive use of cementitious materials in the geo-engineered barrier as a buffer and borehole sealing material and to ensure the mechanical stability of disposal systems. In order to assess the radionuclide (RN) retention potential of these barrier materials, it is necessary to study the impact of various repository relevant conditions that will evolve over time, such as changed pH values, increased ionic strength, elevated temperatures, or the release of organic components. The U(VI) retention by calcium (aluminate) silicate hydrate (C-(A-)S-H) phases, forming owing to Al-rich additives in cement formulations, was studied for samples with C/S molar ratios of 0.8, 1.2, and 1.6, representing different alteration stages of concrete, and with increasing A/S molar ratios of 0, 0.06, and 0.18 in each series, with special focus on the presence of organics. The latter thereby comprise gluconate (GLU), 2-phosphonobutane-1,2,4,-tricarboxylate (PBTC), and a mixture of cellulose degradation products (CDP) obtained from dry radiolysis (dose rate 0.6 kGy/h, absorbed dose ~ 1.37 MGy) followed by hydrolysis in artificial cement water (pH > 13, anoxic conditions) provided by project partners within the CORI framework. Complementary analytical techniques were applied to address the different specific aspects of the cement / organics / RN ternary systems. 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (XRD) were applied to determine the bulk structure and composition of the synthesized C-(A-)S-H phases. 13C-, and in case of PBTC also 31P-, MAS NMR measurements aimed at localization and speciation of the organic components involved [1]. 1H and 31P solution NMR of the aqueous phase allowed for quantification of the organics’ fraction removed from solution and hence associated with the solid phase. Retained U(VI) species were identified by time-resolved las

The world’s increasing demand for energy and supplying this energy dominantlyfrom fossil fuels has a major impact on global climate change. Theenergy crisis has gotten more alarming in the recent years which increasedthe motivation for replacing fossil fuels with greener routes for energy harvest.There are various technologies developed for harvesting energy, andthe ability to recover energy from waste heat at a wide range of temperatures (from room temperature to more than 1000 ∘C) distinguished thethermoelectric (TE) materials from the rest. The drawback about the thermoelectricdevices is that they are too inefficient to be cost-effective in manyapplications, and the developments in nanotechnology is providing somesolutions to increase the efficiency of these materials and devices. The field of thermoelectrics suffer from large discrepancy of theresults in the literature, which is generally attributed to the variations inthe materials qualities, urging a need for the development of synthetictechniques that can lead to large-scale TE materials in reasonable timeframe. In this thesis, three different routes for rapid, scalable, and energyefficient, wet-chemical synthetic techniques for bismuth chalcogenidecompounds are presented. Microwave assisted heating during reactionprovided better control over the particle properties while reducing thereaction time and carbon footprint of the synthetic method, leading tomaterials bismuth chalcogenides with promising TE transport propertiesin a scalable and reproducible manner. Hybrid TE materials, and recently emerging solid-liquid TE materialsconcept, requires fabrication of porous TE films, to study the effect of variousinterfaces, including solid and liquid electrolytes. For this purpose, wedeveloped and optimized the electrophoretic deposition (EPD) process toprepare nanostructured porous TE films by preserving the size and morphologyof the as-synthesized bismuth chalcogenide particles. A new glass based substrate is desig, Världens ökande efterfrågan på energi och att tillhandahålla denna energifrämst från fossila bränslen har en betydande inverkan på den globalaklimatförändringen. Energikrisen har blivit allt mer alarmerande de senasteåren, vilket har ökat motivationen att ersätta fossila bränslen med grönaenergilösningar. Det har utvecklats olika tekniker för energiutvinning, menförmågan att återvinna energi från spillvärme vid ett brett temperaturintervall(från rumstemperatur till över 1000 °C) skiljer termoelektriska (TE)material från övriga. Nackdelen med TE-enheter är att de är för ineffektivaför att vara kostnadseffektiva i många tillämpningar, där utvecklingen inomnanoteknik erbjuder vissa lösningar för att öka effektiviteten hos dessamaterial och enheter. Inom området för TE-material finns det stora avvikelser i resultaten i litteraturen,vilket i allmänhet tillskrivs variationer i materialkvaliteten. Detfinns ett behov av att utveckla syntetiska tekniker som kan leda till högeffektivaTE-material i storskalig produktion på rimlig tid. I denna avhandlingpresenteras tre olika metoder för snabb, skalbar och energieffektiv våtkemisksyntetisering av bismutkalkogenidföreningar. Mikrovågsassisteraduppvärmning under reaktionen gav bättre kontroll över partikelegenskapernasamtidigt som reaktionstiden och koldioxidavtrycket för den syntetiskametoden minskade, vilket resulterade i bismutkalkogenider med lovandeTE-transportegenskaper på ett skalbart och reproducerbart sätt. Hybrida TE-material och det nyligen framkomna konceptet med fastvätska-TE-material kräver framställning av porösa TE-filmer för att studeraeffekten av olika gränssnitt, inklusive fasta och flytande elektrolyter. Fördetta ändamål har vi utvecklat och optimerat elektroforesdepositionsprocessen(EPD) för att framställa nanostrukturerade porösa TE-filmer genomatt bevara storlek och morfologi hos de syntetiserade bismutkalkogenidpartiklarna. En ett nytt substrat baserat på glas har designats och tillverkats föratt studera de, QC 2023-08-21

The synthesis of zeolites without using an organic structure-directing agent (OSDA) offers great environmental and economic advantages; however, the zeolites being formed are not stabilized by the organic molecules and kinetic control of the synthesis ensuring high yield and purity of the phases is challenging for many zeolites. For OSDA-free synthesis of an Al-rich *BEA zeolite, this study shows that the zeolite is formed as a metastable phase that can undergo transformation immediately after completion of its crystallization to form a thermodynamically more stable MOR zeolite according to Ostwald's rule of stages. The OSDA-free zeolite synthesis is a dynamic process in which crystallization and dissolution occur simultaneously. As soon as a thermodynamically more stable MOR zeolite begins to form in the synthesis mixture, its formation causes depletion of the Al and Si from the synthesis mixture, and, because of the desaturation of the synthesis gel, the original *BEA zeolite begins to dissolve rapidly under hydrothermal conditions. The formation of targeted and parasitic zeolite structures is fundamentally affected by the Al and Si sources. Sources of Al and Si with suitable solubility and the presence of stable zeolite *BEA seeds allow kinetic control to direct the exclusive formation of *BEA zeolite up to a relatively high yields. Then, however, the MOR zeolite phase appears in the product and its formation becomes predominant. This study demonstrates the crucial importance of kinetic control for the selective formation of metastable zeolites in the OSDA-free synthesis., Syntéza zeolitů bez použití činidla usměrňujícího organickou strukturu přináší ekonomické úspory a je mnohem příznivější pro životní prostředí. Ovšem bez přítomnosti organických molekul, které by stabilizovali cíleno strukturu zeolitu je kinetika reakce i výsledná čistota produktu s dostatečným výtěžkem obtížná pro řadu zeolitů. V případě této studie, kde byl připraven *BEA zeolit je zjištěno, že zeolit vzniká jako metastabilní fáze a transformuje se ihned po ukončení své krystalizace a přechází na termodynamicky stabilnější MOR zeolit. Z experimentů vyplývá, že tvorba cíleného a nežádoucího zeolitu je výrazně ovlivněna zdrojem Al a Si. Dále je zřejmé, že pro selektivní vznik vybraného zeolitu bez použití činidla usměrňujícího organickou strukturu je velmi důležité řídit kinetiku celého procesu.

The world’s increasing demand for energy and supplying this energy dominantlyfrom fossil fuels has a major impact on global climate change. Theenergy crisis has gotten more alarming in the recent years which increasedthe motivation for replacing fossil fuels with greener routes for energy harvest.There are various technologies developed for harvesting energy, andthe ability to recover energy from waste heat at a wide range of temperatures (from room temperature to more than 1000 ∘C) distinguished thethermoelectric (TE) materials from the rest. The drawback about the thermoelectricdevices is that they are too inefficient to be cost-effective in manyapplications, and the developments in nanotechnology is providing somesolutions to increase the efficiency of these materials and devices. The field of thermoelectrics suffer from large discrepancy of theresults in the literature, which is generally attributed to the variations inthe materials qualities, urging a need for the development of synthetictechniques that can lead to large-scale TE materials in reasonable timeframe. In this thesis, three different routes for rapid, scalable, and energyefficient, wet-chemical synthetic techniques for bismuth chalcogenidecompounds are presented. Microwave assisted heating during reactionprovided better control over the particle properties while reducing thereaction time and carbon footprint of the synthetic method, leading tomaterials bismuth chalcogenides with promising TE transport propertiesin a scalable and reproducible manner. Hybrid TE materials, and recently emerging solid-liquid TE materialsconcept, requires fabrication of porous TE films, to study the effect of variousinterfaces, including solid and liquid electrolytes. For this purpose, wedeveloped and optimized the electrophoretic deposition (EPD) process toprepare nanostructured porous TE films by preserving the size and morphologyof the as-synthesized bismuth chalcogenide particles. A new glass based substrate is desig, Världens ökande efterfrågan på energi och att tillhandahålla denna energifrämst från fossila bränslen har en betydande inverkan på den globalaklimatförändringen. Energikrisen har blivit allt mer alarmerande de senasteåren, vilket har ökat motivationen att ersätta fossila bränslen med grönaenergilösningar. Det har utvecklats olika tekniker för energiutvinning, menförmågan att återvinna energi från spillvärme vid ett brett temperaturintervall(från rumstemperatur till över 1000 °C) skiljer termoelektriska (TE)material från övriga. Nackdelen med TE-enheter är att de är för ineffektivaför att vara kostnadseffektiva i många tillämpningar, där utvecklingen inomnanoteknik erbjuder vissa lösningar för att öka effektiviteten hos dessamaterial och enheter. Inom området för TE-material finns det stora avvikelser i resultaten i litteraturen,vilket i allmänhet tillskrivs variationer i materialkvaliteten. Detfinns ett behov av att utveckla syntetiska tekniker som kan leda till högeffektivaTE-material i storskalig produktion på rimlig tid. I denna avhandlingpresenteras tre olika metoder för snabb, skalbar och energieffektiv våtkemisksyntetisering av bismutkalkogenidföreningar. Mikrovågsassisteraduppvärmning under reaktionen gav bättre kontroll över partikelegenskapernasamtidigt som reaktionstiden och koldioxidavtrycket för den syntetiskametoden minskade, vilket resulterade i bismutkalkogenider med lovandeTE-transportegenskaper på ett skalbart och reproducerbart sätt. Hybrida TE-material och det nyligen framkomna konceptet med fastvätska-TE-material kräver framställning av porösa TE-filmer för att studeraeffekten av olika gränssnitt, inklusive fasta och flytande elektrolyter. Fördetta ändamål har vi utvecklat och optimerat elektroforesdepositionsprocessen(EPD) för att framställa nanostrukturerade porösa TE-filmer genomatt bevara storlek och morfologi hos de syntetiserade bismutkalkogenidpartiklarna. En ett nytt substrat baserat på glas har designats och tillverkats föratt studera de, QC 2023-08-21

In this work, in order to improve the photocatalytic efficiency of ZnO, the optimal CeO2 content in ZnO powders was determined by varying the quantity of CeO2 from 0 to 10 mol%. The structural, microstructural, optical, textural, and photocatalytic properties of the hydrothermally obtained ZnO and CeO2/ZnO nanocomposites have been investigated by using the XRPD, FESEM, HRTEM/SAED, BET, and UV–Vis techniques. Detailed characterization revealed that CeO2, having spherical nanodots of about 5 nm with a large surface area, was distributed onto the ZnO surface, whose crystallites displayed a bimodal distribution, from nano-to micro-crystals. The morphology of ZnO is a combination of nanograins and microrods that further makes a 3-D tie-like morphology. The nanocomposite containing 5 mol% of CeO2 showed about 30% better photocatalytic efficiency in the degradation of Reactive Orange 16 dye compared to other samples under simulated solar radiation. In addition, the kinetics and mechanism of photocatalytic degradation were also proposed based on the photocatalytic activity and scavenger tests.

The world’s increasing demand for energy and supplying this energy dominantlyfrom fossil fuels has a major impact on global climate change. Theenergy crisis has gotten more alarming in the recent years which increasedthe motivation for replacing fossil fuels with greener routes for energy harvest.There are various technologies developed for harvesting energy, andthe ability to recover energy from waste heat at a wide range of temperatures (from room temperature to more than 1000 ∘C) distinguished thethermoelectric (TE) materials from the rest. The drawback about the thermoelectricdevices is that they are too inefficient to be cost-effective in manyapplications, and the developments in nanotechnology is providing somesolutions to increase the efficiency of these materials and devices. The field of thermoelectrics suffer from large discrepancy of theresults in the literature, which is generally attributed to the variations inthe materials qualities, urging a need for the development of synthetictechniques that can lead to large-scale TE materials in reasonable timeframe. In this thesis, three different routes for rapid, scalable, and energyefficient, wet-chemical synthetic techniques for bismuth chalcogenidecompounds are presented. Microwave assisted heating during reactionprovided better control over the particle properties while reducing thereaction time and carbon footprint of the synthetic method, leading tomaterials bismuth chalcogenides with promising TE transport propertiesin a scalable and reproducible manner. Hybrid TE materials, and recently emerging solid-liquid TE materialsconcept, requires fabrication of porous TE films, to study the effect of variousinterfaces, including solid and liquid electrolytes. For this purpose, wedeveloped and optimized the electrophoretic deposition (EPD) process toprepare nanostructured porous TE films by preserving the size and morphologyof the as-synthesized bismuth chalcogenide particles. A new glass based substrate is desig, Världens ökande efterfrågan på energi och att tillhandahålla denna energifrämst från fossila bränslen har en betydande inverkan på den globalaklimatförändringen. Energikrisen har blivit allt mer alarmerande de senasteåren, vilket har ökat motivationen att ersätta fossila bränslen med grönaenergilösningar. Det har utvecklats olika tekniker för energiutvinning, menförmågan att återvinna energi från spillvärme vid ett brett temperaturintervall(från rumstemperatur till över 1000 °C) skiljer termoelektriska (TE)material från övriga. Nackdelen med TE-enheter är att de är för ineffektivaför att vara kostnadseffektiva i många tillämpningar, där utvecklingen inomnanoteknik erbjuder vissa lösningar för att öka effektiviteten hos dessamaterial och enheter. Inom området för TE-material finns det stora avvikelser i resultaten i litteraturen,vilket i allmänhet tillskrivs variationer i materialkvaliteten. Detfinns ett behov av att utveckla syntetiska tekniker som kan leda till högeffektivaTE-material i storskalig produktion på rimlig tid. I denna avhandlingpresenteras tre olika metoder för snabb, skalbar och energieffektiv våtkemisksyntetisering av bismutkalkogenidföreningar. Mikrovågsassisteraduppvärmning under reaktionen gav bättre kontroll över partikelegenskapernasamtidigt som reaktionstiden och koldioxidavtrycket för den syntetiskametoden minskade, vilket resulterade i bismutkalkogenider med lovandeTE-transportegenskaper på ett skalbart och reproducerbart sätt. Hybrida TE-material och det nyligen framkomna konceptet med fastvätska-TE-material kräver framställning av porösa TE-filmer för att studeraeffekten av olika gränssnitt, inklusive fasta och flytande elektrolyter. Fördetta ändamål har vi utvecklat och optimerat elektroforesdepositionsprocessen(EPD) för att framställa nanostrukturerade porösa TE-filmer genomatt bevara storlek och morfologi hos de syntetiserade bismutkalkogenidpartiklarna. En ett nytt substrat baserat på glas har designats och tillverkats föratt studera de, QC 2023-08-21

There are ten million people in the world who have Parkinson’s disease. The most potent medicine for Parkinson’s disease is levodopa (L-DOPA). However, long-term consumption of L-DOPA leads to the appearance of side effects, as a result of which the control and monitoring of its concentrations are of great importance. In this work, we have designed a new electrochemical sensor for detecting L-DOPA using a carbon paste electrode (CPE) modified with Eu2O3@Cr2O3 composite nanoparticles. Rare earth elements, including Eu, are increasingly used to design new electrode nanocomposites with enhanced electrocatalytic properties. Europium has been considered a significant lanthanide element with greater redox reaction behavior. We conducted a hydrothermal synthesis of Eu2O3@Cr2O3 and, for the first time, the acquired nanoparticles were used to modify CPE. The proposed Eu2O3@Cr2O3/CPE electrode was investigated in terms of its electrocatalytic properties and then used to develop an analytical method for detecting and quantifying L-DOPA. The proposed sensor offers a wide linear range (1–100 µM), high sensitivity (1.38 µA µM−1 cm−2 ) and a low detection limit (0.72 µM). The practical application of the proposed sensor was investigated by analyzing commercially available pharmaceutical tablets of L-DOPA. The corresponding results indicate the excellent potential of the Eu2O3@Cr2O3/CPE sensor for application in real-time L-DOPA detection

In this work, in order to improve the photocatalytic efficiency of ZnO, the optimal CeO2 content in ZnO powders was determined by varying the quantity of CeO2 from 0 to 10 mol%. The structural, microstructural, optical, textural, and photocatalytic properties of the hydrothermally obtained ZnO and CeO2/ZnO nanocomposites have been investigated by using the XRPD, FESEM, HRTEM/SAED, BET, and UV–Vis techniques. Detailed characterization revealed that CeO2, having spherical nanodots of about 5 nm with a large surface area, was distributed onto the ZnO surface, whose crystallites displayed a bimodal distribution, from nano-to micro-crystals. The morphology of ZnO is a combination of nanograins and microrods that further makes a 3-D tie-like morphology. The nanocomposite containing 5 mol% of CeO2 showed about 30% better photocatalytic efficiency in the degradation of Reactive Orange 16 dye compared to other samples under simulated solar radiation. In addition, the kinetics and mechanism of photocatalytic degradation were also proposed based on the photocatalytic activity and scavenger tests.

In this work, in order to improve the photocatalytic efficiency of ZnO, the optimal CeO2 content in ZnO powders was determined by varying the quantity of CeO2 from 0 to 10 mol%. The structural, microstructural, optical, textural, and photocatalytic properties of the hydrothermally obtained ZnO and CeO2/ZnO nanocomposites have been investigated by using the XRPD, FESEM, HRTEM/SAED, BET, and UV–Vis techniques. Detailed characterization revealed that CeO2, having spherical nanodots of about 5 nm with a large surface area, was distributed onto the ZnO surface, whose crystallites displayed a bimodal distribution, from nano-to micro-crystals. The morphology of ZnO is a combination of nanograins and microrods that further makes a 3-D tie-like morphology. The nanocomposite containing 5 mol% of CeO2 showed about 30% better photocatalytic efficiency in the degradation of Reactive Orange 16 dye compared to other samples under simulated solar radiation. In addition, the kinetics and mechanism of photocatalytic degradation were also proposed based on the photocatalytic activity and scavenger tests.

There are ten million people in the world who have Parkinson’s disease. The most potent medicine for Parkinson’s disease is levodopa (L-DOPA). However, long-term consumption of L-DOPA leads to the appearance of side effects, as a result of which the control and monitoring of its concentrations are of great importance. In this work, we have designed a new electrochemical sensor for detecting L-DOPA using a carbon paste electrode (CPE) modified with Eu2O3@Cr2O3 composite nanoparticles. Rare earth elements, including Eu, are increasingly used to design new electrode nanocomposites with enhanced electrocatalytic properties. Europium has been considered a significant lanthanide element with greater redox reaction behavior. We conducted a hydrothermal synthesis of Eu2O3@Cr2O3 and, for the first time, the acquired nanoparticles were used to modify CPE. The proposed Eu2O3@Cr2O3/CPE electrode was investigated in terms of its electrocatalytic properties and then used to develop an analytical method for detecting and quantifying L-DOPA. The proposed sensor offers a wide linear range (1–100 µM), high sensitivity (1.38 µA µM−1 cm−2) and a low detection limit (0.72 µM). The practical application of the proposed sensor was investigated by analyzing commercially available pharmaceutical tablets of L-DOPA. The corresponding results indicate the excellent potential of the Eu2O3@Cr2O3/CPE sensor for application in real-time L-DOPA detection.

Stable, water-soluble titanium complexed with mandelic acid was used as a precursor for titanium phosphorus double oxide obtained in hydrothermal conditions in the presence of phosphoric acid. Surprisingly, hydrolysis of organic complexes provided a microstructured sphere with narrow size distribution, low aggregation and a small fraction of morphological irregularities. Obtained microspheres had a complex structure comprised of flakes, whose size could be manipulated with temperature conditions. Samples were found to be electrochemically active against sulcotrione, a well-recognized herbicide. Electrochemical sensors based on the synthesized microspheres were successfully adapted for natural water reservoir analysis and exhibited low levels of detection of 0.61 µM, limit of quantification of 1.86 µM, wide dynamic linear range from 2 to 200 µM, good selectivity, excellent reproducibility and in-time stability.

There are ten million people in the world who have Parkinson’s disease. The most potent medicine for Parkinson’s disease is levodopa (L-DOPA). However, long-term consumption of L-DOPA leads to the appearance of side effects, as a result of which the control and monitoring of its concentrations are of great importance. In this work, we have designed a new electrochemical sensor for detecting L-DOPA using a carbon paste electrode (CPE) modified with Eu2O3@Cr2O3 composite nanoparticles. Rare earth elements, including Eu, are increasingly used to design new electrode nanocomposites with enhanced electrocatalytic properties. Europium has been considered a significant lanthanide element with greater redox reaction behavior. We conducted a hydrothermal synthesis of Eu2O3@Cr2O3 and, for the first time, the acquired nanoparticles were used to modify CPE. The proposed Eu2O3@Cr2O3/CPE electrode was investigated in terms of its electrocatalytic properties and then used to develop an analytical method for detecting and quantifying L-DOPA. The proposed sensor offers a wide linear range (1–100 µM), high sensitivity (1.38 µA µM−1 cm−2) and a low detection limit (0.72 µM). The practical application of the proposed sensor was investigated by analyzing commercially available pharmaceutical tablets of L-DOPA. The corresponding results indicate the excellent potential of the Eu2O3@Cr2O3/CPE sensor for application in real-time L-DOPA detection.

Stable, water-soluble titanium complexed with mandelic acid was used as a precursor for titanium phosphorus double oxide obtained in hydrothermal conditions in the presence of phosphoric acid. Surprisingly, hydrolysis of organic complexes provided a microstructured sphere with narrow size distribution, low aggregation and a small fraction of morphological irregularities. Obtained microspheres had a complex structure comprised of flakes, whose size could be manipulated with temperature conditions. Samples were found to be electrochemically active against sulcotrione, a well-recognized herbicide. Electrochemical sensors based on the synthesized microspheres were successfully adapted for natural water reservoir analysis and exhibited low levels of detection of 0.61 µM, limit of quantification of 1.86 µM, wide dynamic linear range from 2 to 200 µM, good selectivity, excellent reproducibility and in-time stability.

Despite great attention toward transition metal tellurates especially M3TeO6 (M = transition metal) in magnetoelectric applications, control on single phasic morphology-oriented growth of these tellurates at the nanoscale is still missing. Herein, a hydrothermal synthesis is performed to synthesize single-phased nanocrystals of two metal tellurates, i.e., Ni3TeO6 (NTO with average particle size ∼37 nm) and Cu3TeO6 (CTO ∼ 140 nm), using NaOH as an additive. This method favors the synthesis of pure NTO and CTO nanoparticles without the incorporation of Na at pH = 7 in MTO crystal structures such as Na2M2TeO6, as it happens in conventional synthesis approaches such as solid-state reaction and/or coprecipitation. Systematic characterization techniques utilizing in-house and synchrotron-based characterization methods for the morphological, structural, electronic, magnetic, and photoconductivity properties of nanomaterials showed the absence of Na in individual particulate single-phase MTO nanocrystals. Prepared MTO nanocrystals also exhibit slightly higher antiferromagnetic interactions (e.g., TN-NTO = 57 K and TN-CTO = 68 K) compared to previously reported MTO single crystals. Interestingly, NTO and CTO show not only a semiconducting nature but also photoconductivity. The proposed design scheme opens the door to any metal tellurates for controllable synthesis toward different applications. Moreover, the photoconductivity results of MTO nanomaterials prepared serve as a preliminary proof of concept for potential application as photodetectors.

Stable, water-soluble titanium complexed with mandelic acid was used as a precursor for titanium phosphorus double oxide obtained in hydrothermal conditions in the presence of phosphoric acid. Surprisingly, hydrolysis of organic complexes provided a microstructured sphere with narrow size distribution, low aggregation and a small fraction of morphological irregularities. Obtained microspheres had a complex structure comprised of flakes, whose size could be manipulated with temperature conditions. Samples were found to be electrochemically active against sulcotrione, a well-recognized herbicide. Electrochemical sensors based on the synthesized microspheres were successfully adapted for natural water reservoir analysis and exhibited low levels of detection of 0.61 µM, limit of quantification of 1.86 µM, wide dynamic linear range from 2 to 200 µM, good selectivity, excellent reproducibility and in-time stability.

The design of a green photocatalytic system that harnesses renewable and eco-friendly constituents holds the potential to offer valuable insights into alternative strategies for treating toxic multi-components in refinery water effluents. A significant challenge in implementing a practical and viable approach is the utilization of solar energy-an abundant, natural, and cost-effective resource-for photochemical processes within advanced oxidation processes. In this study, we explored the use of zinc oxide nanoparticles (ZnO NPs) as photocatalyst prepared via an environmentally friendly synthesis approach, resulting in the formation of crystalline wurtzite nanoparticles, with an average size of about 14 nm relatively spherical in shape. Notably, the extract derived from Moringa oleifera was employed in this investigation. These nanoparticles were characterized and validated using various characterization techniques, including X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. For comparison, conventionally synthesized ZnO NPs were also included in the evaluations. The findings reveal that, under illumination, biosynthesized ZnO nanoparticles (NPs) exhibit photocatalytic performance in effectively breaking down the organic compounds present in synthetic petroleum wastewater. Photochemical analysis further illustrates the degradation efficiency of Green-ZnO, which, within 180 min of irradiation resulted in 51%, 52%, 88%, and 93% of removal for Phenol, O-Cresol. Under optimal loading conditions, NPs produced via the green synthesis approach perform better when compared to chemically synthesized ZnO. This significant improvement in photocatalytic activity underscores the potential of eco

CRUE-CSIC (Acuerdos Transformativos 2022), Erbium/ytterbium-dopped Y0.9Er0.1−xYbxVO4 samples with x = 0, 0.01, 0.05 and 0.09 were synthesized by hydrothermal synthesis at basic pH with urea addition. For comparison purposes, another sample with x = 0 was also prepared by the solgel method. X-ray diffraction patterns were indexed on the basis to a tetragonal symmetry of space group I41/amd with Z = 4 compatible with a zircon-type, in good agreement with FTIR spectra. Additionally, some of the samples were coated with silica, and the successful coating process was verified in both X-ray diffraction profiles and FTIR spectra. Particles of two different morphologies were found in transmission electron microscopy images of uncoated samples, some spherical with sizes between 14 and 20 nm and others elongated. A shell of ~ 5 nm thickness was also observed in silica covered samples. The relationship between dopant content and the luminescence emission was systematically explored. Erbium-doped samples exhibit bright green fluorescence under stimulation at 360 nm. The substitution of erbium by ytterbium successfully produced an up-conversion emission under stimulation at 808 nm, being able to observe green and red emission bands. The potential use as fluorescent thermometers of erbium/ ytterbium doped samples at 300, 325 and 350 K was finally investigated, Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III (ISCIII), Comunidad de Madrid, Universidad Autónoma de Madrid/Comunidad de Madrid, Ministerio de Universidades, Depto. de Química Física, Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

The management of salt slag, a waste from the secondary aluminum industry, is associated with huge environmental concerns due to the risk of atmospheric pollution (emission of toxic gases), groundwater contamination (high salt content that can percolate and cause an increase in salinity) and soil unavailability (large extensions required for disposal). Therefore, the development of a sustainable process for its treatment and recovery is of the utmost importance. In this work, a two-step process for the valorization of salt slag was developed that rendered zeolite as the main added-value product and NaCl and NH3 as byproducts. First, salt slag was hydrolyzed at 90 °C and at a solid/water ratio of 1/3. More than 90% of salt and ~90% of ammonia were recovered. In a second step, the hydrolyzed slag was completely transformed into a NaP zeolite under mild hydrothermal conditions. The zeolite exhibited specific surface area (17 m2 g−1), cation exchange capacity (2.12 meq g−1) and zeta potential (−52 mV) values that represent good characteristics for use in the removal of metal ions from aqueous effluents. The transformation of salt slag into zeolite can be considered a sustainable process with a high contribution to the circular economy., by Alusigma S.A., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Nickel ferrite samples are currently investigated due to their potential technological applications. For this reason, the optimal synthesis conditions of nickel ferrite samples with small particle size were investigated here. First, a systematic study was carried out using urea as an additive, and varying reaction parameter such as the amount of urea added or the reaction temperature and time. For comparison purposes, another sample was synthesized using potassium hydroxide as an additive. The two pure nickel ferrite samples were coated with silica, functionalizing them with APTES and AEPMDS. X-rays, FTIR, Mössbauer spectroscopy, TEM and Ms vs. H and FC/ZFC curves were used for the characterization of samples and the evaluation of their properties. Square particles with an average size of 21.2 nm were observed in the TEM images of the sample synthesized with urea, while these are spherical of 6.2 nm in the sample prepared with potash. Their subsequent coating and functionalization give rise to an arrangement of particles within interlocking strands whose thickness increases with their size. Ms vs. H curves confirm the almost superparamagnetic behavior of all synthesized powders, although with a slight increase in the coercivity value of the samples prepared with urea. Preliminary tests carried out on the functionalized samples to evaluate the adsorption capacity in aqueous solution and their easy separation in presence of an external magnetic field, confirm that the sample syn thesized with urea and functionalized with AEPDMS is the most efficient for the Cu2+ ions removal., Fundación Neurociencias y Envejecimiento (España), Ministerio de Economía y Competitividad (España), Comunidad de Madrid, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Depto. de Química Inorgánica, Depto. de Química Física, Fac. de Ciencias Químicas, TRUE, pub

[ES] Las zeolitas son sólidos inorgánicos, microporosos y cristalinos compuestos por la unión de tetraedros TO4 (T = Si, Ge, B, Al, Ti, ...). Estos tetraedros están unidos unos con otros por sus vértices, formando sistemas de canales y cavidades de dimensiones moleculares. Las propiedades de las zeolitas varían en función de la composición química de su estructura y de la topología y tamaño de sus canales. Por ello, el rango de aplicación de las zeolitas en la industria es muy amplio, presentando un especial interés en procesos de catálisis, adsorción y separación. Existen zeolitas con estructuras interesantes para su aplicación como catalizadores en reacciones químicas de interés industrial, pero que, debido a la composición química de su estructura, presentan una baja estabilidad y/o una pequeña o nula cantidad de centros activos. Un ejemplo son las zeolitas ITQ-13 (ITH), ITQ-15 (UTL), ITQ-24 (IWR) e ITQ-34 (ITR). La presente tesis doctoral se ha centrado en la síntesis de dichas estructuras zeolíticas, realizando modificaciones en su composición química para su posterior aplicación como catalizadores. Mediante la optimización de los procesos de síntesis hidrotermal y el desarrollo de diferentes tratamientos post-síntesis, se ha aumentado considerablemente la estabilidad de la estructura zeolítica y la fortaleza ácida de las zeolitas ITQ-13, ITQ-15, ITQ-24 e ITQ-34. Además, en las zeolitas ITQ-15 e ITQ-24 ha sido posible la incorporación de titanio en sus estructuras. Todos los procesos desarrollados evitan problemas presentes en los procesos de síntesis descritos en bibliografía para estas zeolitas, como problemas de obturación de los sistemas de canales o problemas de reproducibilidad. Por otro lado, se ha estudiado la utilización de ADEs quirales para la síntesis de zeolitas con propiedades enantioselectivas, además de las descritas previamente, para su utilización en procesos de catálisis asimétrica., [CAT] Les zeolites són sòlids inorgànics, microporosos i cristal·lins compostos per la unió de tetraedres TO4 (T = Si, Ge, B, Al, Ti, ...). Aquests tetraedres estan units uns amb altres pels seus vèrtexs, formant sistemes de canals i cavitats de dimensions moleculars. Les propietats de les zeolites varien en funció de la composició química de la seua estructura i de la topologia i dimensions dels seus canals. Per això, el rang d'aplicació de les zeolites en la indústria és molt ampli, presentant un especial interès en processos de catàlisi, adsorció i separació. Hi ha zeolites amb estructures interessants per a la seua aplicació com a catalitzadors en reaccions químiques d'interès industrial, però que presenten una baixa estabilitat i/o una xicoteta o nul·la quantitat de centres actius a causa de la composició de la seua estructura. Un exemple són les zeolites ITQ-13 (ITH), ITQ-15 (UTL), ITQ-24 (IWR) i ITQ-34 (ITR). La present tesi doctoral, s'ha centrat en la síntesi de les dites estructures zeolítiques amb modificacions en la seua composició química per a un posterior us com catalitzadors. Per mitjà de l'optimització dels processos de síntesi hidrotermal i el desenvolupament de diferents tractaments post-síntesi, s'ha augmentat considerablement l'estabilitat de l'estructura zeolítica i la fortalesa àcida de les zeolites ITQ-13, ITQ-15, ITQ-24 i ITQ-34. A més, en les zeolites ITQ-15 i ITQ-24 ha sigut possible la incorporació de titani en les seues estructures. Tots els processos desenvolupats eviten problemes presents en els processos de síntesis descrits en bibliografia per a aquestes zeolites, como a problemes d'obturació dels sistemes de canals o problemes de reproductibilitat. D'altra banda, s'ha estudiat la utilització d'ADEs quirals per a la síntesi de zeolites amb propietats enantioselectives, a més de les descrites prèviament, per a la seua utilització en processos de catàlisi asimètrica., [EN] Zeolites are inorganic, microporous and crystalline materials formed by linking together tetrahedrons TO4 (T = Si, Ge, B, Al, Ti, ...). These tetrahedrons are connected with each other by their vertexes forming channels systems and cavities of molecular dimensions. Zeolite properties vary depending on the chemical composition of its framework and the topology and size of its channels. Because of that, zeolites have a wide field of industrial applications, notably in catalytic, adsorption and separation processes. There are zeolites with interesting structures to its application as catalysts in chemical reactions of industrial relevance, but its chemical composition gives rise to a material with low stability and/or small or zero amount of acid centers. An example are the zeolites ITQ-13 (ITH), ITQ-15 (UTL), ITQ-24 (IWR) and ITQ-34 (ITR). Taking account the good possibilities of these zeolites as catalyst, this thesis is focused on their synthesis with chemical composition modifications. The zeolitic framework stability and the acidic strength in zeolites ITQ-13, ITQ-15, ITQ-24 and ITQ-34 have been significantly enhanced. That has been possible by the optimization of the hydrothermal synthesis processes and the development of different post-synthesis treatments. In addition, titanium has been incorporated to the framework structures of ITQ-15 and ITQ-24 zeolites. All the developed processes avoid the problems present in the synthesis processes described in the literature for these zeolites, such as the partial blockage of the channel system or reproducibility problems. Furthermore, chiral organic compounds are studied as SDA in the synthesis of zeolites with enantioselective properties, with the objective to their use in asymmetric catalysis processes.

[ES] Las zeolitas son sólidos inorgánicos, microporosos y cristalinos compuestos por la unión de tetraedros TO4 (T = Si, Ge, B, Al, Ti, ...). Estos tetraedros están unidos unos con otros por sus vértices, formando sistemas de canales y cavidades de dimensiones moleculares. Las propiedades de las zeolitas varían en función de la composición química de su estructura y de la topología y tamaño de sus canales. Por ello, el rango de aplicación de las zeolitas en la industria es muy amplio, presentando un especial interés en procesos de catálisis, adsorción y separación. Existen zeolitas con estructuras interesantes para su aplicación como catalizadores en reacciones químicas de interés industrial, pero que, debido a la composición química de su estructura, presentan una baja estabilidad y/o una pequeña o nula cantidad de centros activos. Un ejemplo son las zeolitas ITQ-13 (ITH), ITQ-15 (UTL), ITQ-24 (IWR) e ITQ-34 (ITR). La presente tesis doctoral se ha centrado en la síntesis de dichas estructuras zeolíticas, realizando modificaciones en su composición química para su posterior aplicación como catalizadores. Mediante la optimización de los procesos de síntesis hidrotermal y el desarrollo de diferentes tratamientos post-síntesis, se ha aumentado considerablemente la estabilidad de la estructura zeolítica y la fortaleza ácida de las zeolitas ITQ-13, ITQ-15, ITQ-24 e ITQ-34. Además, en las zeolitas ITQ-15 e ITQ-24 ha sido posible la incorporación de titanio en sus estructuras. Todos los procesos desarrollados evitan problemas presentes en los procesos de síntesis descritos en bibliografía para estas zeolitas, como problemas de obturación de los sistemas de canales o problemas de reproducibilidad. Por otro lado, se ha estudiado la utilización de ADEs quirales para la síntesis de zeolitas con propiedades enantioselectivas, además de las descritas previamente, para su utilización en procesos de catálisis asimétrica., [CAT] Les zeolites són sòlids inorgànics, microporosos i cristal·lins compostos per la unió de tetraedres TO4 (T = Si, Ge, B, Al, Ti, ...). Aquests tetraedres estan units uns amb altres pels seus vèrtexs, formant sistemes de canals i cavitats de dimensions moleculars. Les propietats de les zeolites varien en funció de la composició química de la seua estructura i de la topologia i dimensions dels seus canals. Per això, el rang d'aplicació de les zeolites en la indústria és molt ampli, presentant un especial interès en processos de catàlisi, adsorció i separació. Hi ha zeolites amb estructures interessants per a la seua aplicació com a catalitzadors en reaccions químiques d'interès industrial, però que presenten una baixa estabilitat i/o una xicoteta o nul·la quantitat de centres actius a causa de la composició de la seua estructura. Un exemple són les zeolites ITQ-13 (ITH), ITQ-15 (UTL), ITQ-24 (IWR) i ITQ-34 (ITR). La present tesi doctoral, s'ha centrat en la síntesi de les dites estructures zeolítiques amb modificacions en la seua composició química per a un posterior us com catalitzadors. Per mitjà de l'optimització dels processos de síntesi hidrotermal i el desenvolupament de diferents tractaments post-síntesi, s'ha augmentat considerablement l'estabilitat de l'estructura zeolítica i la fortalesa àcida de les zeolites ITQ-13, ITQ-15, ITQ-24 i ITQ-34. A més, en les zeolites ITQ-15 i ITQ-24 ha sigut possible la incorporació de titani en les seues estructures. Tots els processos desenvolupats eviten problemes presents en els processos de síntesis descrits en bibliografia per a aquestes zeolites, como a problemes d'obturació dels sistemes de canals o problemes de reproductibilitat. D'altra banda, s'ha estudiat la utilització d'ADEs quirals per a la síntesi de zeolites amb propietats enantioselectives, a més de les descrites prèviament, per a la seua utilització en processos de catàlisi asimètrica., [EN] Zeolites are inorganic, microporous and crystalline materials formed by linking together tetrahedrons TO4 (T = Si, Ge, B, Al, Ti, ...). These tetrahedrons are connected with each other by their vertexes forming channels systems and cavities of molecular dimensions. Zeolite properties vary depending on the chemical composition of its framework and the topology and size of its channels. Because of that, zeolites have a wide field of industrial applications, notably in catalytic, adsorption and separation processes. There are zeolites with interesting structures to its application as catalysts in chemical reactions of industrial relevance, but its chemical composition gives rise to a material with low stability and/or small or zero amount of acid centers. An example are the zeolites ITQ-13 (ITH), ITQ-15 (UTL), ITQ-24 (IWR) and ITQ-34 (ITR). Taking account the good possibilities of these zeolites as catalyst, this thesis is focused on their synthesis with chemical composition modifications. The zeolitic framework stability and the acidic strength in zeolites ITQ-13, ITQ-15, ITQ-24 and ITQ-34 have been significantly enhanced. That has been possible by the optimization of the hydrothermal synthesis processes and the development of different post-synthesis treatments. In addition, titanium has been incorporated to the framework structures of ITQ-15 and ITQ-24 zeolites. All the developed processes avoid the problems present in the synthesis processes described in the literature for these zeolites, such as the partial blockage of the channel system or reproducibility problems. Furthermore, chiral organic compounds are studied as SDA in the synthesis of zeolites with enantioselective properties, with the objective to their use in asymmetric catalysis processes.

Carbonaceous solid-phase extraction (SPE) sorbent, efficient in isolation and enrichment of multiclass pesticides and pharmaceuticals from water, was synthesized starting from cheap waste beech sawdust and using KOH as the activated agent. The first step in carbon material preparation was hydrothermal carbonization of the waste beech sawdust. Following hydrothermal treatment, the obtained material was activated, using different amounts of KOH. It was found that applied activation leads to changes in material structure, an increase in specific surface area, and a decrease in the number of surface oxygen groups compared to carbonized sample. SPE procedure of multiclass pesticides and pharmaceuticals from water using activated carbonized beech sawdust (AcSD) was optimized by selecting the appropriate elution solvents, the sample pH, and the sample volume to obtain the highest enrichment efficiency. The optimized SPE procedure was applied for water analysis using different AcSD samples as a sorbent for analyte preconcentration. Activated carbon sorbent, obtained with the highest amount of KOH, showed the highest recoveries regarding the most analytes, which were comparable with the recoveries obtained by commercial cartridges. © 2022 Serbian Chemical Society. All rights reserved.

Carbonaceous solid-phase extraction (SPE) sorbent, efficient in isol-ation and enrichment of multiclass pesticides and pharmaceuticals from water, was synthesized starting from cheap waste beech sawdust and using KOH as the activated agent. The first step in carbon material preparation was hydrother-mal carbonization of the waste beech sawdust. Following hydrothermal treat-ment, the obtained material was activated, using different amounts of KOH. It was found that applied activation leads to changes in material structure, an inc-rease in specific surface area, and a decrease in the number of surface oxygen groups compared to carbonized sample. SPE procedure of multiclass pesticides and pharmaceuticals from water using activated carbonized beech sawdust (AcSD) was optimized by selecting the appropriate elution solvents, the sample pH, and the sample volume to obtain the highest enrichment efficiency. The optimized SPE procedure was applied for water analysis using different AcSD samples as a sorbent for analyte preconcentration. Activated carbon sorbent, obtained with the highest amount of KOH, showed the highest recoveries reg-arding the most analytes, which were comparable with the recoveries obtained by commercial cartridges.

Nanostructured surfaces have recently been established as a novel surface technology to alleviate health and industrial problems caused by bacterial biofilms. Whilst fundamental research has advanced, nanostructure arrays have generally only been developed on 2D, flat substrates, and evaluated by incubating bacteria parallel to nanostructure direction. These circumstances do not reflect real-world surfaces which are often curved and randomly oriented with respect to sedimentation direction. Titanium dioxide nanostructures on 3D, hemisphere-shaped substrates were fabricated using hydrothermal synthesis to investigate the effects of curvature and orientation on bactericidal performance. 3D surfaces were 91% more efficient at resisting Staphylococcus aureus adhesion compared to 2D surfaces, and cells that did attach were killed with the same or higher efficiency after 1 and 3 h exposure to nanostructured surfaces. This preliminary study establishes hydrothermal synthesis as a viable fabrication method of 3D bactericidal surfaces and provides insight into surface curvature and orientation impact on bactericidal efficiency.

In this study, the influence of boron doping on structural and surface properties of carbon material synthesized by a hydrothermal method was investigated, and the obtained results were compared with the previously published influence that boron has on characteristics of carbonized boron-doped hydrothermal carbons (CHTCB). Hydrothermal carbons doped with boron (HTCB) were obtained by the hydrothermal synthesis of glucose solutions with different nominal concentrations of boric acid. It was found that glucose based hydrothermal carbon does not have developed porosity, and the presence of boron in their structure has insignificant influence on it. On the contrary, additional carbonization increases the specific surface area of the undoped sample, while an increase in boron content drastically decreases the specific surface area. Boron doping leads to a decrease in the amount of surface oxygen groups, for both, hydrothermally synthesized and additionally carbonized materials. Raman analysis showed that the boron content does not affect a structural arrangement of the HTCB samples, and Raman structural parameters show a higher degree of disorder, compared to the CHTCB samples. Comparison of structural and surface characteristics of hydrothermal carbons and carbonized materials contributes to the study of the so far, insufficiently clarified influence that boron incorporation has on the material characteristics. © 2022 Serbian Chemical Society. All rights reserved.

Carbonaceous solid-phase extraction (SPE) sorbent, efficient in isol-ation and enrichment of multiclass pesticides and pharmaceuticals from water, was synthesized starting from cheap waste beech sawdust and using KOH as the activated agent. The first step in carbon material preparation was hydrother-mal carbonization of the waste beech sawdust. Following hydrothermal treat-ment, the obtained material was activated, using different amounts of KOH. It was found that applied activation leads to changes in material structure, an inc-rease in specific surface area, and a decrease in the number of surface oxygen groups compared to carbonized sample. SPE procedure of multiclass pesticides and pharmaceuticals from water using activated carbonized beech sawdust (AcSD) was optimized by selecting the appropriate elution solvents, the sample pH, and the sample volume to obtain the highest enrichment efficiency. The optimized SPE procedure was applied for water analysis using different AcSD samples as a sorbent for analyte preconcentration. Activated carbon sorbent, obtained with the highest amount of KOH, showed the highest recoveries reg-arding the most analytes, which were comparable with the recoveries obtained by commercial cartridges.

Gallium nitride (GaN) and indium gallium nitride (InGaN) nanostructures, and their nanocomposites with reduced graphene oxide (rGO) are prepared by solvothermal method and used as sensing materials for ammonia gas. The ammonia sensing characteristics are studied by coating the synthesized GaN and InGaN nanostructures, and their nanocomposites on interdigitated electrodes. The sensing parameters, i.e., sensing response, selectivity, and stability, are studied for various operating temperatures and relative humidity. The pristine GaN and InGaN exhibit a sensing response of 23.8% and 28.1% for 200 ppm concentration at 300 K, whereas the nanocomposites of GaN and InGaN show an increased response of 37.4% and 44.2%. This improvement in the nanocomposites maybe ascribed to the better conductivity, higher number of gas adsorption sites and reduced bandgap. It is found that these materials are an excellent choice for ammonia gas sensing application., QC 20220615

Assembly of thermoelectric nanostructures with pre-defined morphology and surface chemistry on solid sub-strates has been one of the challenges for in-plane TE devices. Electrophoretic deposition (EPD) has the potential to be used for this purpose, where the use of non-conductive substrates is required to enable a reliable evaluation of the transport property of electrically active films. Bi2Te3 nanoparticles, which were synthesized using microwave-assisted hydrothermal route, were used for the EPD of thermoelectric films on glass substrates. A special substrate was fabricated using maskless photolithography, to evaluate the electronic transport properties of the TE films without the interference of the substrate. Electrolyte composition was optimized for high mobility of the suspended nanoparticles, and Bi2Te3 EPD films were fabricated with a high deposition rate, reaching 10 mu m/min. Initial EPD films showed high resistivity, ascribed to the surface oxide layer and capping ligands. The resistance was significantly reduced by the addition of a dithiol molecular linker, capable of interconnecting the Bi2Te3 nanoparticles through ligand-exchange. Seebeck coefficient in the range-150 to-180 mu V/K was measured, revealing the transport through the deposited films. Finally, a power factor of 169 nW/K-2.m was estimated, revealing the potential for the application of this technology to large area TE films as active coatings using the developed EPD process., QC 20220818

In this study, the influence of boron doping on structural and surface properties of carbon material synthesized by a hydrothermal method was investigated, and the obtained results were compared with the previously published influence that boron has on characteristics of carbonized boron-doped hydrothermal carbons (CHTCB). Hydrothermal carbons doped with boron (HTCB) were obtained by the hydrothermal synthesis of glucose solutions with different nominal concentrations of boric acid. It was found that glucose based hydrothermal carbon does not have developed porosity, and the presence of boron in their structure has insignificant influence on it. On the contrary, additional carbonization increases the specific surface area of the undoped sample, while an increase in boron content drastically decreases the specific surface area. Boron doping leads to a decrease in the amount of surface oxygen groups, for both, hydrothermally synthesized and additionally carbonized materials. Raman analysis showed that the boron content does not affect a structural arrangement of the HTCB samples, and Raman structural parameters show a higher degree of disorder, compared to the CHTCB samples. Comparison of structural and surface characteristics of hydrothermal carbons and carbonized materials contributes to the study of the so far, insufficiently clarified influence that boron incorporation has on the material characteristics. © 2022 Serbian Chemical Society. All rights reserved.

The structural, microstructural, optical and photocatalytic properties of hydrothermally obtained single-phase ZnO and CeO2@ZnO nanocomposites have been investigated by the XRPD, FESEM, HRTEM/SAED and UV-vis techniques. In order to improve the photocatalytic efficiency of ZnO, the optimal CeO2 content in ZnO powders was determined by varying the quantity of CeO2 from 0 to 10 mol%. The results showed that CeO2 with spherical crystallites of about 5 nm was distributed onto the ZnO surface, whose crystallites displayed a bimodal distribution, from nano- to microcrystallites. The morphology of ZnO particles varied from elongated nanograins to microrods that further formed a 3-D tie-like morphology which was disrupted by CeO2 adding. By degrading 90% of RO16 dye in 180 minutes, the composite containing 5 mol% of CeO2 showed approximately for 30% better photocatalytic efficiency comparing to other samples, although all the obtained powders have similar structural, microstructural and optical characteristics. This is obviously the optimal ratio of these two phases, in which synergy of CeO2 adsorption and ZnO photocatalytic effect reaches its maximum due to reduced recombination rate and improved adsorption. The kinetic of RO16 degradation could be described by a pseudo-first order model.

Manganese dioxide compounds are widely used in electrochemical applications e.g. as electrode materials or photocatalysts. One of the most used polymorphs is gamma-MnO2 which is a disordered intergrowth of pyrolusite beta-MnO2 and ramsdellite R-MnO2. The presence of intergrowth defects alters the material properties, however, they are difficult to characterise using standard X-ray diffraction due to anisotropic broadening of Bragg reflections. We here propose a characterisation method for intergrown structures by modelling of X-ray diffraction patterns and pair distribution functions (PDF) using gamma-MnO2 as an example. Firstly, we present a fast peak-fitting analysis approach, where features in experimental diffraction patterns and PDFs are matched to simulated patterns from intergrowth structures, allowing quick characterisation of defect densities. Secondly, we present a structure-mining-based analysis using simulated gamma-MnO2 superstructures which are compared to our experimental data to extract trends on defect densities with synthesis conditions. We applied the methodology to a series of gamma-MnO2 samples synthesised by a hydrothermal route. Our results show that with synthesis time, the intergrowth structure reorders from a R-like to a beta-like structure, with the beta-MnO2 fraction ranging from ca. 27 to 82% in the samples investigated here. Further analysis of the structure-mining results using machine learning can enable extraction of more nanostructural information such as the distribution and size of intergrown domains in the structure. Using this analysis, we observe segregation of R- and beta-MnO2 domains in the manganese oxide nanoparticles. While R-MnO2 domains keep a constant size of ca. 1-2 nm, the beta-MnO2 domains grow with synthesis time.

In this study, we report a straightforward and reproducible hydrothermal synthesis of copper oxide nanowires, their morphological and chemical characterization, and their application in gas sensing. Results show that the hydrothermal process is mainly influenced by the reaction time and the concentration of the reducing agent, demonstrating the synthesis of fine and long nanowires (diameter of 50–200 nm and length of 25 µm) after 10 h of reaction with 0.1 M of pyrrole. Two different annealing temperatures were tested (205 and 450 °C) and their effect on the morphology, chemical composition, and crystal size of the nanowires was analyzed by SEM, XPS, and XRD techniques, respectively. The analysis shows that the Cu2+ oxidation state is mainly obtained at the higher annealing temperature, and the nanowires’ shape suffers a transformation due to the formation of agglomerated crystallites. The gas sensing tests for acetone, ethanol, toluene, and carbon monoxide show preferential response and sensitivity to acetone and ethanol over the other analytes. The annealing temperature proves to have a higher influence on the stability of the nanowires than on their gas sensitivity and selectivity, showing better medium-term stability for the nanowires annealed at 450 °C.