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© 2021 Chinese Society of Rare EarthsIn this research, un-doped CeO2 and Ce0.85La0.10M0.05O2 (M: Sm, Er, Y) compounds were synthesized by hydrothermal method and the multi-functional properties are reported. Oxygen defects were created with the additives of rare earth ions. The electrical and luminescence behaviors of the synthesized compounds were investigated in accord with the types of additives. The synthesized products were characterized by X-ray diffraction (XRD) analysis, Brunauere–Emmette–Teller (BET) measurement, UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopic (EIS). All synthesized compounds are found to be nano-structured and have cubic phase. The total conductivity of all samples was calculated. Hence, the total conductivity of un-doped CeO2, Ce0.85La0.10Y0.05O2, Ce0.85La0.10Er0.05O2 and Ce0.85La0.10Sm0.05O2 is found to be 2.07 × 10−10, 5.70 × 10−4, 1.0 × 10−3 and 0.0747 S/cm, respectively. Also, bandgap energy (Eg) of these samples calculated from UV visible absorption spectra is discussed, and the optical results show variation between 3.2 and 2.15 eV. Additionally, the luminescence properties of the compounds were investigated and different emissions occur depending on the additive type. Accordingly, photoluminescent emission spectra of Ce0.85La0.10Y0.05O2, Ce0.85La0.10Er0.05O2 and Ce0.85La0.10Sm0.05O2 phosphors indicate that these phosphors have red, green and orange-red colors, respectively.

A series of Sm–Mn mixed oxide catalysts were prepared via precipitation using various precipitants, namely Na2CO3 (NH4)2CO3, and NH3·H2O, and evaluated for the selective catalytic reduction (SCR) of NOx with NH3 at low temperatures. Various characterisation techniques were used to determine the physicochemical properties of the catalysts, and it is found that their catalytic performance is greatly influenced by the nature of the precipitation agent used. It is found that Sm0.1Mn–Na2CO3 and Sm0.1Mn-(NH4)2CO3 exhibit superior catalytic performance in the SCR reaction to that of Sm0.1Mn–NH3·H2O due to an abundance of surface acid sites, high surface concentration of Mn4+, and high NO oxidation capacity. From in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analysis, we conclude that the Sm–Mn catalysts follow both Eley-Rideal and Langmuir–Hinshelwood mechanisms, and that the Eley-Rideal mechanism is dominant at elevated temperatures.

In this study, the photocatalytic activity of Nd-TiO2 photocatalysts obtained by common hydrothermal method were evaluated by practical experiments and theoretical calculations based on Density functional theory (DFT). The synthesized photocatalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) to study their physical/chemical properties. At the same time, the photoelectronic performance was also investigated. The photodegradation ability of as-prepared photocatalysts and the effect of Nd doped amount and photocatalysts dosage were investigated by the photodegradation of phenol (30 mg/L) under 400 W metal halide lamp (UV-Vis). The effect of Nd on electronic properties of TiO2 and adsorption ability of phenol were discussed. Results show that the red-shift wavelength of 0.5 mol%Nd-TiO2, indicating its absorption capacity is stronger than pristine TiO2 in the same wavelength range. The result of DFT calculations demonstrate that the optical bandgap of Nd-TiO2 is profoundly reduced, thus the light absorption ability is promoted, which will be responsible for the enhanced photocatalytic performance of Nd-TiO2. 0.5 mol%Nd is an optimum value for photodegradation phenol, and phenol can be completely degraded by 0.5 mol%Nd-TiO2 for 210 min, the higher catalytic performance is derived from the efficient separation of e–/h+ pairs. Moreover, the adsorption energy calculations of phenol on TiO2 (101) and Nd-TiO2 (101) demonstrate that the Nd doping can significantly enhance the adsorption ability of phenol on catalyst surfaces because of the formation of Nd–O bonds. At last, the stability measurement through four recycles exhibits that 0.5 mol%Nd-TiO2 possesses excellent stability.

The construction of efficient photocatalysts has received much attention in wastewater treatment. In this study, Nb-doped NaTaO3 was prepared with different doping ratio by a facile hydrothermal method. The prepared catalysts were analyzed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) theory, ultraviolet-visible diffuse reflectance spectroscopy (DRS). Then the synthesized catalysts were employed to degrade a model pollutant, methylene blue (MB), under a 250W mercury lamp. The characterization tests confirm that Nb was successfully doped into the crystal structure of NaTaO3 and the modified NaNbxTa1−xO3 (x is the doping ratio; x=0.25, 0.5, 0.75) samples were formed, which were in regular cubic shapes just like pure NaTaO3. The synthesized NaNbxTa1−xO3 (x=0.25, 0.5, 0.75) had improved specific surface area and narrowed band gaps compared with pure NaTaO3. In photocatalytic degradation experiments, NaNb0.75Ta0.25O3 presented the best photocatalytic activity ascribed to the narrow band gap and the high surface area, degradating 95.7% of MB after 180 minutes of reaction, which was even twice the ability of pure NaTaO3. Besides, the effects of possible inorganic anions and cations in wastewater on photocatalytic degradation were investigated. Electron spin resonance (ESR) tests and capture experiments were also conducted and a possible photocatalytic mechanism was proposed. This work provides a direction for constructing superior NaTaO3-based photocatalysts to be widely utilized in environmental protection.

The catalytic elimination of nitrogen-containing volatile organic compounds (NVOCs) still encounters bottlenecks in NOx formation and low N2 selectivity. Here, a series of Cu-promoted Ce-Zr mixed oxide catalysts were synthesized using a simple precipitation approach, and n-butylamine was adopted as the probe pollutant to evaluate their catalytic performance. The CeCu10%ZrOx catalyst exhibited the best catalytic activity, with 100% n-butylamine conversion and 90% N2 selectivity at 250 °C. Concurrently, this sample also displayed good water resistance. A detailed characterization of the catalyst was performed through a series of experimental studies and theoretical calculations. The addition of Cu increased the redox property and promoted the production of oxygen vacancies, all of which were favorable for the greatest n-butylamine selective catalytic oxidation performance. The changes of oxygen vacancies over CeCu10%ZrOx in reaction process were studied by in situ Raman spectra. Moreover, in situ diffuse reflectance infrared Fourier transform spectra (DRIFTs) and theoretical calculations were employed to explore the reaction mechanism of n-butylamine selective oxidation. The high activity and selectivity of this catalyst confirm the practical feasibility of the selective oxidation of n-butylamine to CO2 and N2, and the exploration of the reaction mechanism provides new insights into the further design of catalysts.

Bismuth-rich Bi5O7Br is a promising photocatalyst for pollutant removal owing to its stability and appropriate band structure in comparison with bismuth oxybromide. However, bulk-phase Bi5O7Br suffers from poor light absorption and high charge recombination rates resulting in poor activity. Elemental doping is a powerful strategy to enhance photocatalytic activity. In this study, we prepared a series of Br auto-doped ultrathin Bi5O7Br nanotubes and explored the effect of Br doping on photocatalytic NO removal. The optimal doping content was determined via a photocatalytic NO removal experiment, which revealed the optimal ratio of Bi and Br was approximately 3:1. In situ diffuse reflectance infrared Fourier transform spectroscopy (In situ DRIFT) and density functional theory (DFT) studies revealed that NO removal mechanism catalyzed by Br doped Bi5O7Br. Our work presents a new strategy for the enhancement of photocatalytic pollutant degradation by bismuth oxyhalide photocatalysts.

The Y, F, and Ag tridoped TiO2/SnO2 composite nanocrystalline film (YFAg–TS) with prominent photocatalytic performance was prepared by the modified sol–gel method and was characterized by utilizing X-ray diffraction (XRD), differential thermal and thermogravimetric (DTA–TG) analysis, scanning tunneling microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence (PL). The XRD and DTA–TG results expose that the YFAg–TS catalyst is a mixed phase consisting of anatase, rutile, and chlorargyrite, which is beneficial to improving the photocatalytic performance of TiO2. The SEM, TEM, and BET results disclose that the YFAg–TS film has smaller nanoparticles, higher surface area, and narrower pore size compared with pure TiO2 film. The XRD and TEM results exhibit that a part of yttrium can enter the TiO2 lattice to induce lattice distortion. The XPS results confirm the presence of Y3+ state in the YFAg–TS sample, and Y3+ ions can act as the trapping site of electrons to expedite the separation of electrons and holes. The UV–vis DRS results reveal that the YFAg–TS film has an obvious absorption edge shift and a narrower bandgap (2.70 eV) compared with pure TiO2 film. The PL results show that the YFAg–TS film has the highest photogenerated electrons and holes separation efficiency and charges transfer efficiency among all samples. The photocatalytic activity of the YFAg–TS is assessed by monitoring the degradation of methyl green and formaldehyde solution. The results manifest that the YFAg–TS film has high stability and excellent photocatalytic performance. The possible synergistic photocatalytic mechanism of YFAg–TS films has been discussed in this paper.

A novel SrSn(OH)6 photocatalyst with large plate and particle size were synthesized via a facile chemical precipitation method. The photocatalytic activity of the SrSn(OH)6 was evaluated by the removal of NO at ppb level under UV light irradiation. Based on the ESR measurements, SrSn(OH)6 photocatalyst was found to have the ability to generate the main active species of O2•−, •OH, and 1O2 during the photocatalytic process. Moreover, SrSn(OH)6 photocatalyst not only exhibits high photocatalytic activity for NO removal (79.6%), but also has good stability after five cycles. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to investigate the NOx transfer pathway and the intermediate products distribution during the adsorption and photocatalytic NO oxidation process. The present work not only provides an efficient material for air pollutants purification at room temperature but also in-depth understanding of the mechanism involved in the photocatalytic NO removal process.

The hydrophobic ionic liquids/water two-phase system was developed to prepare CuO nano particles. The catalytic activity of the synthesized CuO was investigated by photodegradation of 4-nitrophenol (4-NP) in the presence of H2O2 under visible light irradiation. The optical properties of the synthesized CuO were characterized by ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS). Experimental results indicated that the band gap energy (Eg), conduction band edge potential (ECB) and valence band edge potential (EVB) of the synthesized CuO were 1.37 eV, 0.625 eV and 1.995 eV, respectively. A degradation efficiency of 4-NP (4.8 mmol L−1) as high as 95.3% could be achieved under the conditions of pH 6.0, 0.48 g L−1 of CuO dosage, 1.4% of H2O2 dosage and 90 min of degradation time. The synthesized CuO exhibited poor catalytic activity under alkaline conditions due to the disassociation of 4-NP, which elevated the repulsion between CuO and the 4-NP anions. The synthesized CuO nano particles exhibited higher catalytic activity compared with the catalysts reported in literature. Furthermore, the synthesized CuO nano particles could be reused at least six times without decreasing their catalytic activity. Compared with the traditional hydrothermal method, mild operating conditions and time saving are the advantages of the developed method for the preparation of CuO.

Catalysts consisting of highly dispersed copper on a mesoporous ZrO2 support were synthesised via a one-pot sol-gel synthesis and were tested for the selective catalytic reduction of NOx by NH3. The copper dispersion was investigated by XRD and TEM, which showed no discernible copper oxide particles up to 6 wt% Cu, while they were detected at 15 wt% Cu., NH3 adsorption and the SCR reaction were followed in situ by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) on mesoporous ZrO2 and on one-pot synthesized 3 wt% Cu/ZrO2. Cu was found to improve the NH3 adsorption capacity of the catalyst by enhancing the Lewis functionality., The catalysts were efficient for SCR at low temperature, at 150 degrees C 75% of NO was converted over 6 wt% Cu/ ZrO2 at water-free conditions. Increasing the copper loading while maintaining the dispersion improved NOx conversion.

A new porphyrinic vanadium-based metal-organic framework (MOF), namely V-MOF-10 [V2(OH)2(H2TCPP)], constructed from {V(OH)O4}∞ chains and 4-tetracarboxyphenylporphyrin linkers, was synthesized by the solvothermal procedure. Structural analysis indicated that V-MOF-10 possesses the orthorhombic symmetry featured with two types of pores (5.2 × 11.9 A and 3.5 × 11.9 A). Full characterization of V-MOF-10 was analyzed by powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and elemental analysis (EA). N2 isotherm of V-MOF-10 at 77 K shows a reversible uptake and permanent porosity with a high BET (Langmuir) surface area of 1477 m2 g-1 (1553 m2 g-1). The optical band gap of V-MOF-10, measured by UV-Vis diffuse reflectance spectroscopy, is calculated to be 1.71 eV, resulting in a shift of absorption wavelength to the visible light region. Furthermore, our density functional theory (DFT) calculations confirm an acceptable correspondence of the band gap value with the mentioned experimental investigation, similar to the incorporated experimental and theoretical observations in the previous literature. Remarkably, V-MOF-10 exhibits an excellent photocatalytic property of organic dyes with the degradation efficiency of 100% for methylene blue (MB) and 89% for methylene orange (MB) after 120 min under illumination by visible light. These results suggest that V-MOF-10 could be used as a promising candidate in further photocatalytic studies.

A series of BiO(OH)xI1–x solid solution (SS) catalysts were successfully prepared by ion exchange of I− and OH− between the [Bi2O2]2+ layers. The morphology and microstructure were studied in depth using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) method, etc. Tunable absorption in the visible-light region was achieved by changing the proportion of OH– to I−. Due to the etching effect of OH−, oxygen vacancies (OVs) greatly increased for the SS catalysts, and were confirmed by X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and electron paramagnetic spectroscopy (EPR). The unique composition of OH−, I−, OV, and [Bi2O2]2+ layers in BiO(OH)xI1–x materials resulted in diverse photoexcitations. The BiO(OH)0.45I0.55 photocatalyst displayed a 10-fold-improved 2-chlorophenol (2-CP) degradation rate compared to BiOI. The interfacial reaction process by the photoinduced valence-band holes and conduction-band electrons proved to be a more efficient pathway for organic pollutant degradation by the BiO(OH)xI1–x SS photocatalyst. The OVs in the SS photocatalyst facilitated photoexcited and electron migration and transformation.

The Cu2+ doped CuxMg0.5Zn0.5-xFe2O4 [x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5] ferrite nanoparticles were synthesized by co-precipitation method using oxalate precipitant. The synthesized oxalate precursors have been characterized by Elemental analysis, FT-IR and Thermogravimetry. The structural and optical properties of final ferrite samples have been investigated by X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FT-IR) and UV–Vis Diffuse Reflectance Spectroscopy. The XRD patterns reveals no additional peaks due to second phase i.e. single phase cubic Cu-Mg-Zn ferrites nanoparticles are formed. The parameters like theoretical and experimental lattice constant, crystallite size, X-ray density and unit cell volume extracted from XRD data. It is noticed that with increasing Cu2+ doping lattice parameter and unit cell volume are decreased while X-ray densities are increased. The interionic distances like ionic radii, bond lengths, hopping lengths and anion-anion distance were also evaluated. FT-IR spectra exhibit two distinct absorption bands in the range of 568–589 cm−1 and 448–461 cm−1 which are characteristic of ferrite. Different force constants and Debye temperature for synthesized samples found in agreement with literature. The absorption spectra and Energy band gaps are evaluated by using UV–Vis DRS. The energy band gaps Cu-Mg-Zn ferrites found in the range of 1.643 eV–1.557 eV. UV–Vis DRS analysis showed that the band gap energy decreases with increasing Cu2+ doping.

The SrWO4/Bi2O3 nanocomposite was gotten by co-precipitation process and described by X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), Thermal gravimetric analysis (TGA) and Raman spectroscopy estimations. Average crystallite sizes calculated by XRD are 33 nm for Bi2O3 and 29 nm for SrWO4 changed Bi2O3. The visible light photocatalytic action of the synthesized nanocomposite was assessed by the methylene blue (MB) degradation in visible illumination irradiation. SrWO4/ Bi2O3 have enhanced photocatalytic action for the degradation of MB when contrasted with that of Bi2O3 and SrWO4. Maximum degradation of 99% was accomplished with SrWO4/ Bi2O3 concentration of 0.1 g/L, initial concentration of 10 µM of MB and 180 min illumination time. The improved photocatalytic activity of the nanocomposite was credited to successful electron–hole division.

Recently, In2O3-based catalysts have shown great promise in methanol synthesis from CO2 hydrogenation due to their high methanol selectivity. However, low CO2 conversion restricts their application. Herein, we report In2O3 combined with zeolitic imidazolate framework (ZIF)-derived Co–Zn/C–N catalysts for the CO2 hydrogenation reaction in a fixed-bed reactor. The catalysts were characterized by X-ray diffractometry, transmission electron microscopy, CO2 and H2 temperature desorption measurements, X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. Compared to pure In2O3, In–Co–Zn/C–N-4 (PM) shows higher CO2 conversion, with even higher methanol selectivity. A CO2 conversion of 7.0% was achieved with a methanol selectivity over 77% and the space time yield (STY) of methanol was 3.3 mmol gcat−1 h−1 under the conditions of H2/CO2 = 3 : 1, 2 MPa, 300 °C and GHSV = 6 L gcat−1 h−1. The In–Co–Zn/C–N-4 (IMP) catalyst shows much lower methanol selectivity (46.6%) and stability due to the formation of Co3InC0.75. ZnO effectively weakens the interactions between Co and In, and the physically-mixed method further prevents the formation of Co3InC0.75. DRIFTS results were used to predict the possible methanol and CO production pathway through a formate intermediate for the In–Co–Zn/C–N catalyst.

In the present study, the influence of phase purity and crystallinity on the electrochemical properties of well-designed GdBiVO4@rGO nanocomposite has been fabricated by the facile hydrothermal method for the detection of chloramphenicol (Cp) were reported. The surface morphology and electrochemical sensing property of as prepared samples had characterized by X-ray diffraction spectroscopy (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray photoelectron microscopy (XPS), UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) and Electron Impedance Spectroscopy (EIS) techniques. The electrochemical property of synthesized GdBiVO4@rGO nanocomposite had carried out for the detection of hazardous antiprotozoal chloramphenicol (CP) drug in food had scrutinized by Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). The GdBiVO4@rGO nanocomposite on electrode showed an excellent and quick response towards CP drug. Under an optimized condition, the proposed electrochemical sensor displayed a low detection limit of up to 0.0229 μM and broad linear range of 0.05–36.55 & 42.55-2336.55 μM for CP. In addition, the GdBiVO4@rGO electrodes exhibited good performance characteristics of repeatability and reproducibility and proved suitable for CP analysis in food samples.

Boron-doped titanium dioxide nanoparticles (B–TiO2 NPs) were prepared by a sol-gel method. The physicochemical properties of B–TiO2 NPs were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy and photoluminescence spectroscopy. The band structure and electrical properties of B–TiO2 NPs were investigated using the first-principle. The effects of the concentration gradient of doping B ions on the photocatalytic antibacterial activity of B–TiO2 NPs under visible-light irradiation were investigated by the inhibition zone method and the shaking flask method. The experimental results show that B–TiO2 NPs are mainly composed of the anatase phase, but no B-related phase was observed. With the increase of the doping amount of boron ions, the particle size decreases and the specific surface area increases. B atoms mainly exist in the form of substitutional dopant and interstitial dopant. Theoretical calculations reveal that B atoms in the TiO2 matrix exist much more easily as interstitial dopant, but B–TiO2 NPs composed of B substituted dopant have better photocatalytic performance. The results of the antibacterial assays show that B–TiO2 NPs have strong antibacterial activities and some bactericidal activities. Finally, the mechanism of the antibacterial activity of B–TiO2 NPs are examined.

The effect of the modification of an alumina support with chloride on the structure and the catalytic performance of Ag/Al2O3 catalysts (SA) was investigated for the selective catalytic reduction (SCR) of NO using C3H6 or H2/C3H6 as reductants. The Ag/Al2O3 catalyst and Cl−-modified Ag/Al2O3 catalysts (SA-Cl) were prepared by a conventional impregnation method and characterized by X-ray diffraction, Brunauer-Emmett-Teller isotherm analysis, electron probe microanalysis, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction. The catalytic activities in the C3H6-SCR and H2/C3H6-SCR reactions were evaluated, and the reaction mechanism was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy and synchrotron vacuum ultraviolet photoionization mass spectroscopy (SVUV-PIMS). We found that Cl− modification of the alumina-supported Ag/Al2O3 catalysts facilitated the formation of oxidized silver species (Agnδ+) that catalyze the moderate-temperature oxidation of hydrocarbons into partial oxidation products (mainly acetate species) capable of participating in the SCR reaction. The low-temperature promoting effect of H2 on the C3H6-SCR (“hydrogen effect”) was found to originate from the enhanced decomposition of strongly adsorbed nitrates on the catalyst surface and the conversion of these adsorbed species to –NCO and –CN species. This “H2 effect” occurs in the presence of Agnδ+ species rather than the metallic Ag0 species. A gaseous intermediate, acrylonitrile (CH2CHCN), was also identified in the H2/C3H6-SCR reaction using SVUV-PIMS. These findings provide novel insights in the structure-activity relationship and reaction mechanisms of the SA-catalyzed HC-SCR reaction of NO.

Due to the shortage supply of propylene and the development of shale gas, there is increased interest in on-purpose propane dehydrogenation (PDH) technology for propylene production. Ga-based catalysts have great potential in PDH, due to the high activity, low carbon deposit and deactivation. Ga-hydrides formed during PDH reduce the rate, selectivity and yield of propylene. In this contribution, CO2 is introduced into PDH as a soft oxidant to eliminate the unfavorable intermediate species Gaδ+-Hx re-generating Ga3+-O pairs, and also minimize coke deposition thereby improving the catalytic performance. In situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy experiments show that CO2 can effectively eliminate Gaδ+-Hx. At different temperatures, co-feeding CO2 during PDH over Ga2O3/SiO2 catalysts with different loadings significantly improves the stability of the conversion and selectivity, especially the latter, and provide a new dimension for improving the performance of PDH process.

In the present work, ceria/zinc oxide (CeO2/ZnO) nanocomposite has been synthesized by controlled annealing of cerium and zinc precursors. The obtained CeO2/ZnO nanocomposite was characterized using common analytical methods such as Fourier transform infrared spectroscopy (FT-IR), UV-Visible diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectrum (SEM with EDS) and elemental mapping measurements. The band gap energy of CeO2/ZnO nanocomposite was about ∼2.9 eV calculated from the Tauc plot. The XRD pattern of CeO2/ZnO nanocomposite consisted mixed phases of CeO2 and ZnO with crystalline nature. The XPS spectrum of CeO2/ZnO revealed the presence of C, Zn, N, O and Ce elements, where Zn and Ce existed in 2+ and 4+ oxidation states, respectively. The particle size and shape of synthesized CeO2/ZnO nanocomposite was approximately 0.32 µm with a distorted spherical shape identified from the SEM images. The synthesized CeO2/ZnO nanocomposite effectively degraded BG in water and the calculated kinetic rate constant was 0.0471 min−1. The results suggested that CeO2/ZnO nanocomposite behave as a good photocatalyst towards the degradation of BG, identified from the quick degradation as compared with pure ZnO and CeO2. The enhanced catalytic performance of CeO2/ZnO nanocomposite was attributed to the synergistic effect of both CeO2 and ZnO semiconductors, which decrease the bandgap energy and increase the degradation kinetics.

Catalytic conversion of CO2 into methanol utilizing green hydrogen produced from renewable energy is a promising route to realize carbon neutrality. Although ZnZrOx solid solution catalyst displays excellent catalytic performance, it is still highly desired to make any further improvement. Herein, we found the promoting effect of incorporating Ga into ZnZrOx solid solution catalyst in CO2 hydrogenation to methanol. Ga promoted ZnZrOx (GaZnZrOx) solid solution catalyst exhibits CO2 conversion of 8.8% and methanol space time yield of 630 mg gcat−1 h−1 that are higher than those of ZnZrOx solid solution catalyst (7.7%, 556 mg gcat−1 h−1) at 320 °C, while the highly selectivity toward methanol remains unchanged. Chemisorption and H2-D2 exchange results show that GaZnZrOx solid solution catalyst displays higher capacity for the adsorption and activation of H2 than ZnZrOx solid solution catalyst. Electron paramagnetic resonance result suggests that more oxygen vacancies are derived after incorporating Ga into ZnZrOx solid solution catalyst. In situ diffuse reflectance infrared Fourier transform spectra indicate that the HCOO* and CH3O* species are the main intermediate species. The higher IR intensity of intermediate species and lower CH3O*/HCOO* ratio on GaZnZrOx solid solution catalyst suggest that the hydrogenation of HCOO* to CH3O* is boosted. These results reveal the promoting effect of incorporated Ga into ZnZrOx solid solution catalyst that improves the adsorption and activation of H2 and CO2, thus enhancing catalytic performance of methanol synthesis from CO2 hydrogenation.

Iron oxide and Ca-doped ferrite fibers were successfully prepared via Solution Blow Spinning (SBS). Fibers with several calcium contents (nFe/nCa = 3.0, 5.2, and 20.0 atomic ratio) were prepared after dissolving polyvinylpyrrolidone and Fe and Ca nitrates in an acidic aqueous solution, followed by SBS spinning and calcination at 800 °C. The morphological, structural, optical, vibrational, and magnetic properties of the fibers were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), Mossbauer spectroscopy, and magnetometry. The Rietveld refinement revealed Ca-doped fibers consisting of a mixture of Fe2O3, CaFe2O4, and Ca3.6Fe14.4O25.2 crystalline phases. The Mossbauer spectra at 300 K showed a sextet belonging to the hematite phase and two doublets belonging to the calcium-related phases. Measurements at low temperatures showed a transition at 181.6 K attributed to Ca ferrite. The hematite fibers showed a saturation magnetization (Ms ~ 0.75 emu/g) relatively higher than the bulk α-Fe2O3 (Ms = 0.3 emu/g). The saturation magnetization increased from 3.6 to 6.4 emu/g with increasing Ca content.

Transition metals doping has been proved to be a feasible way for tuning the physical properties on the surface and bulk of nanomaterials and also for the good performance in decontamination of emerging pollutants. In this context, doped samples of zinc tin oxide or zinc stannate nanoparticles (ZTO NPs) by several transition metals were synthesized in order to enhance the optical absorbance with the aims of reducing the band gap and therefore ameliorated their photocatalytic activity. They were characterized by the X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy, Raman spectroscopy and photoluminescence. The XRD patterns and the microscopic observations showed the formation of spherical nanoparticles with an average size of about 30 nm and highly pure ZTO phase with an inverse spinel structure. The Raman spectra were dominated by bands relatives to the F2g (2) and A1g symmetries modes of inverse spinel structure. The band gap Eg is estimated to be 3.75 eV for the undoped sample, and 3.67, 3.64, 3.78 and 3.21 eV, for 2% Fe, 2% Mg, 2% Gd, and 2% Mn doped ZTO samples, respectively. Furthermore, the undoped ZTO NPs have the intrinsic problem of recombination of photogenerated charge carriers. We have shown that the reduction of the band gap and oxygen vacancies resulting from the doping effect could be a useful tool for trapping and avoid the recombination of electrons coming from photosensitized rhodamine B (RhB) under visible light irradiation. Owing to the structural advantages and low band gap, 2% Mn doped ZTO NPs, with the kinetic rate constants k of 0.024 min−1, show enhanced performance for the elimination of RhB in aqueous solution compared to undoped and other doped ZTO NPs.

With over 260 tons of gold reserves, the Shuiyindong gold mine is one of the largest Carlin-type gold deposits in China. A particular challenge in the processing of the ore is the presence of carbonaceous compounds, which can cause substantial losses in recoveries via the preg-robbing and adsorption of gold. To investigate the structural properties of the native carbon and to compare between different characterization techniques for such compounds, pre- and post-flotation mineral samples containing 0.9–4.8% non-carbonate carbon from the Shuiyindong mine have been examined via mineralogical and thermogravimetric approaches, as well as spectroscopic techniques, including X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine edge structure spectroscopy (NEXAFS), solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, Raman spectroscopy and preg-robbing measurements. NEXAFS and DRIFT yielded the most reliable results, indicating that 60–75% of the organic carbon in all samples consist of aliphatic alkenes with substantial unsaturated content, highly similar to activated carbon, with the remainder being graphitic and humic. Speciation by XPS was sub-optimal due to spectral overlaps between graphitic and aliphatic carbon, and between carboxylic and carbonate functionalities, while NMR spectroscopy could not provide reliable speciation of the carbon groups. The preg-robbing strength was strongly correlated to the aliphatic content and structural disorder in the carbon, while no such relationship was found with the graphitic and humic content.

We developed an improved hexagonal wurtzite ZnO and ZnO/C microflowers through the facile hydrothermal technique. The obtained nanostructures were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX) and UV–visible diffuse reflectance spectroscopy (UV–Vis DRS). The formation of flower-like material is confirmed using SEM and TEM analysis with an average diameter of about 2 µm composed of several plate-like nanostructures. The optical analysis results show that the presence of carbon particles with ZnO structures has significantly increased the light absorption ability of nanocomposite. The photocatalytic degradation ability of prepared nanostructures was examined using methylene blue as a model pollutant. The obtained results show that the photocatalytic degradation ability of ZnO/C nanostructures is approximately two times higher than the pristine ZnO microflowers. Based on the investigation, an enhancement of the photocatalytic ability of ZnO/C nanocomposite is achieved due to the synergistic effect between carbon particles and flower-like ZnO nanostructures.

Photocatalytic deg radation of environmental pollutants is being up to date for the treatment of contaminated water. In the present study, ZnO/CuO nanomaterials were successfully fabricated by a simple sol-gel method and investigate the photo-degradation of rhodamine B (RhB). The synthesized ZnO/CuO nanoparticles were characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), thermal analysis (TGA), surface charge, and Fourier transform infrared spectroscopy (FTIR). The photo-degradation of the dye RhB was followed spectroscopically. The overall composition of ZnO/CuO material was found to be wurtzite phase, with particle size of 30 nm, and the Vis light absorption increased with an increase of Cu content. The ZnO/CuO nanomaterials were highly active leading to a photo-degradation of 10 ppm RhB reaching 98% within 180 min at 0.1 g/L catalyst dosage. The change in surface charge after degradation evaluated by ζ potential measurements and the differences in functional vibration group monitored by Fourier transform infrared spectroscopy (FTIR) indicates that the RhB adsorption on the Zn45Cu surface was insignificant. And scavenging experiments demonstrate that the RhB degradation by ZnO/CuO nanomaterials involves to some degree hydroxyl radicals.

In this research, hard/soft CoFe2O4/Ni magnetic nanocomposite samples with different concentrations of Ni were successfully produced by a two-step mechanical alloying route. Single-phase CoFe2O4 (CFO), having the average particle size of 35 nm, saturation magnetization of 71 emu/g, and bandgap energy of 2.6 eV was synthesized via the mechanical alloying method. A mixture of as-synthesized CFO and 10, 30 and, 50 wt. % Ni powder has been severely milled to prepare magnetic nanocomposite samples. The effects of different Ni content on the characteristics of the nanocomposite samples have been investigated. FESEM images showed that the ductile nickel powder particles get flattened after 1 h milling, whereas the brittle CFO particles get fragmented by increasing milling time to 10 h. The single-phase-like hysteresis loop, and the switching field distribution curves alongside the simultaneous enhancements of maximum energy product and remanence reflect the presence of exchange spring phenomenon in the nanocomposite samples. Also, the diffuse reflectance spectroscopy (DRS) analysis evidence the reduction of bandgap energy for 10 wt.% Ni containing nanocomposite sample from 2.44 to 2.15 eV on increasing the milling time from 1 to 10 h. Under the optimum photocatalyst operating conditions, the CFO/10 wt% Ni sample exhibited the highest photocatalytic activity of 93.6% for methylene blue (MB) degradation in comparison with the cobalt ferrite sample. Eventually, the detailed kinetic and mechanism to describe the improvement of the photocatalytic performance were suggested.

This work is devoted to the synthesis, optical and dielectric properties of CuBi2O4 prepared by sol–gel route. The X-ray diffraction analysis shows that CuBi2O4 crystallizes in a tetragonal symmetry (SG: P4/cnn) with lattice parameters: a = 8.5023 A and c = 5.8250 A; the Rietveld refinement reveals a high purity of the spinel. The crystallite size (D = 47.84 nm) was calculated from the Williamson Hall-plot. The presence of Cu–O and Bi-O bonds with Cu2+ tetrahedrally coordinated is confirmed by the Raman spectroscopy. We also report the optical and dielectric properties of CuBi2O4, including the refractive index (nλ), optical (σopt) and electrical (σele) conductivities, extinction coefficient (kλ), dissipation factor (tan δ) and relaxation time (τ). The forbidden band (Eg), measured from the UV–Visible diffuse reflectance spectroscopy, is found in the range (1.50–1.55 eV) and confirmed by these approaches. Furthermore, the as-prepared compound has been successfully tested for the first time for the methyl violet degradation under visible light. The results show a conversion rate of 75% under illumination of 4 h 30 min and that the kinetics follows a first order model.

In the present study, alkaline-earth metal scheelite-type compounds ABO4 (A = Ca, Sr, Ba, B = Mo, W) synthesized by a hydrothermal method were systematically studied. The as-obtained photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area analysis (BET), UV–Vis diffuse reflectance spectroscopy (DR/UV-Vis), photoluminescence, and thermoluminescence (TL) spectroscopy together with charge carrier’s lifetime measurements, electron paramagnetic resonance spectroscopy (EPR) and electrochemical impedance spectroscopy (EIS). The photocatalytic activity was studied in the reaction of phenol degradation under simulated solar light. The obtained tungstates and molybdates revealed excellent photocatalytic activity despite the low surface area and wide-bandgap typical for insulators. The mechanism of phenol degradation proceeded through hydroquinone and catechol formation in the presence of hydroxyl and superoxide radicals. The presence of electron traps allowed to absorb light with lower energy than resulting from the absorption edge. BaWO4 and SrWO4, with the most extended average carrier lifetime, were the most efficient photocatalysts from obtained series. In general, molybdates exhibited lower photocatalytic activity towards phenol degradation due to deeper trap states and lower average charge carriers' lifetimes than tungstates. Additionally, electrochemical studies emerged that molybdates exhibit more insulating behavior than tungstates. Overall results showed that wide-bandgap semiconductors, mainly tungstates, can be applied as earth-abundant photocatalytic materials for the degradation of persistent organic pollutants.

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to study noble gas (i.e., He, Kr, and Xe) adsorption in metal-oxide frameworks (MOFs). To study the adsorption of infra...

A Ag3PO4/GO/UiO-66-NH2(AGU) composite photocatalyst was prepared by an ultrasonic-assisted in situ precipitation method. The optical property, structure, composition, and morphology of photocatalysts were investigated using UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy, and charge flow tracking by photodeposition of Pt and PbO2 nanoparticles. In comparison with Ag3PO4 and Ag3PO4/UiO-66-NH2(AU), the AGU composite photocatalyst showed heightened photocatalytic performance for the degradation of levofloxacin hydrochloride (LVF). The AGU photocatalyst (dosage: 0.8 g/L) with 1% mass content of graphene oxide (GO), the mass ratio of Ag3PO4 and UiO-66-NH2(U66N) reached 2:1, showed the highest photodegradation rate of 94.97% for 25 mg/L LVF after 60 min of visible light irradiation at pH = 6. The formation of a heterojunction and the addition of GO synergistically promote faster separation of electron-hole pairs, retain more active substances, and enhance the performance of the photocatalyst. Furthermore, the mechanism of the Z-scheme of the AGU composite photocatalytic is proposed.

In this work, we have investigated the solar reflective and color pigmentation effectiveness of some multifunctional binary oxides, Nb2O5, Ta2O5, Gd2O3, Dy2O3, La2O3, Sb2O3, Cr2O3, Y2O3, SnO2, and MnO2 with the aid of XRD and diffuse reflectance spectroscopy (DRS) techniques. We have also reviewed the recent studies in NIR pigments of multifunctional oxides. From the obtained NIR reflectance values, we note that Gd2O3, Sb2O3, Ta2O5, Nb2O5, and Y2O3 showed interesting features on NIR reflectance on both the solar reflective (750–1350 nm) and color pigmentation region (1350–2500 nm). The oxides like SnO2 and La2O3 demonstrate relatively high solar reflective pigmentation (750–1350 nm) features than color pigmentation. MnO2 and Cr2O3 show low NIR reflectance both in solar and color pigmentation regions as compared to other types of oxides investigated in the present work. Among the different investigated oxides, Nb2O5 exhibits a relatively high NIR reflectance value (~ 85%) in the NIR region (750–2500 nm). On the other hand, the MnO2 powder reveals the lowest NIR reflectance value (15–20%) in the NIR region. The UV–visible absorbance spectra and their energy bandgap of the different oxides have also been compared.

The increased risk of chemical warfare agent usage around the world has intensified the search for high-surface-area materials that can strongly adsorb and actively decompose chemical warfare agents. Dimethyl methylphosphonate (DMMP) is a widely used simulant molecule in laboratory studies for the investigation of the adsorption and decomposition behavior of sarin (GB) gas. In this paper, we explore how DMMP interacts with the as-synthesized mesoporous CeO2. Our mass spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements indicate that DMMP can dissociate on mesoporous CeO2 at room temperature. Two DMMP dissociation pathways are observed. Based on our characterization of the as-synthesized material, we built the pristine and hydroxylated (110) and (111) CeO2 surfaces and simulated the DMMP interaction on these surfaces with density functional theory modeling. Our calculations reveal an extremely low activation energy barrier for DMMP dissociation on the (111) pristine CeO2 surface, which very likely leads to the high activity of mesoporous CeO2 for DMMP decomposition at room temperature. The two reaction pathways are possibly due to the DMMP dissociation on the pristine and hydroxylated CeO2 surfaces. The significantly higher activation energy barrier for DMMP to decompose on the hydroxylated CeO2 surface implies that such a reaction on the hydroxylated CeO2 surface may occur at higher temperatures or proceed after the pristine CeO2 surfaces are saturated.

Considering the present situation of exploitation of TiO2 as a photocatalyst, optimization of its polymorphs (anatase, brookite, and rutile) becomes critical. In the present study, TiO2 nanoparticles have been synthesized using the sol-gel technique to understand the effect of heat treatment-induced anatase-brookite composition on photocatalytic diethyl phthalate removal. The influence of heat treatment on structural characteristics of TiO2 is investigated by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). Bot, XRD and Raman results indicated the coexistence of brookite and anatase. At the same time, UV–visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL) revealed the optical modifications caused by the presence of brookite in the anatase network to alter the photo absorption and photoemission characteristics. The photocatalytic degradation of diethyl phthalate was observed as 95 % under UV–visible illumination (for 225 min) in the presence of the sample, calcined at 200 °C.

Fe–Pr co-doped TiO2 photocatalysts are synthetized by sol–gel method using titanium tetraisopropoxide, praseodymium nitrate and iron acetylacetonate as precursors of titania, praseodymium and iron, respectively. The chemical-physical properties of all prepared samples are analysed by X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) spectroscopy and N2 adsorption at −196 °C. XRD patterns show the main peaks of anatase phase in all photocatalysts and evidence that Fe and Pr ions are effectively introduced into the TiO2 lattice. UV–vis DRS spectra indicate the reduction of the band gap value of Fe-Pr co-doped TiO2 with respect to TiO2 and Pr-doped TiO2 thank to co-doping of TiO2 with Pr and Fe ions. The photocatalytic performances of all prepared samples are investigated for the degradation of Acid Orange 7 azo dye (AO7) and also of phenol under visible light irradiation. Photocatalytic efficiency obtained using Fe–Pr co-doped TiO2 markedly increases compared to un-doped TiO2, Pr-doped TiO2 and Fe-doped TiO2 photocatalysts. Fe-Pr co-doped TiO2 prepared with 8.5 mg of praseodymium nitrate gave the best photocatalytic activity. The enhanced photocatalytic activity should be associated with the simultaneous doping of TiO2 with Pr3+ and Fe3+ ions that induces a marked decrease of band gap value together with an enhanced generation of oxygen vacancies, which can trap electrons, and therefore reducing their recombination with photogenerated positive holes. Indeed, using the optimized Fe-Pr co-doped TiO2, the dye discoloration and mineralization is about 87 and 80 %, respectively, after 60 min of LEDs visible light irradiation, underlining the best performances of the optimized Fe–Pr co-doped TiO2 in terms of treatment time. Finally, the optimized Fe-Pr co-doped TiO2 is tested for visible light degradation of phenol in aqueous solution, confirming the absence of possible sensitization phenomena of photocatalyst surface by the AO7 dye.

New alternative routes to traditional Fischer-Tropsch Synthesis (FTS) must be established to get a more efficient process from the point of view of energy and sustainability. Solar photocatalytic-assisted FTS is a promising new path to obtain fuels from renewable resources. However, proper photocatalysts must be designed to enhance the photocatalytic activity under solar/visible radiation. In this work, Fe and Co-doped TiO2 catalysts were synthesized by a traditional impregnated method and by a hydrothermal route. The oxygen vacancies generation on TiO2 photocatalysts was studied by Raman, XPS and Diffuse Reflectance Spectroscopy (DRS) and correlated with the decrease of the band gap and the photoactivity in the syngas conversion into solar fuels under solar radiation. Metal doping and H2 reduction treatment favour the oxygen vacancies generation that decreases the band gap from 3.3 eV for P25 to values as low as 2.2 and 2.5 eV for Fe- and Co-doped TiO2. This lower band gap increases the methanation activity under solar radiation. Moreover, this metal doping does not only affect the band gap and CO methanation activity under solar radiation but also the CC coupling, favouring the production of ethanol. Thus, in presence of P25, only CO2 and CH4 are obtained whereas the addition of Fe and Co enhances the CH4 generation and favours ethanol production. Therefore, the present work opens new opportunities for the photocatalytic Fischer-Tropsch conversion (PFTS) of crude syngas, which can be obtained from biomass or MSW gasification, into fuels under solar light.

The manuscript describes the key aspects of Zn-Al mixed oxides prepared by different methods (the so-called urea method and co-precipitation methods using either NaOH/Na2CO3 alkaline solution or solution of NaOH) affording high conversion and selectivity values in aldol condensation of furfural with acetone. The structure, composition and acid-base properties of Zn-Al mixed oxides were described by using of TGA, XRD, N2-adsorption, TPD-NH3/CO2 and in-situ diffuse reflectance spectroscopy and correlated with the catalytic performance of a series of Zn-Al mixed-oxides catalysts. Along with the impact of specific surface area and basicity on the furfural conversion, the conversion of furfural also increased with the increasing value of the edge of UV-vis spectrum of Zn-Al mixed oxide reflecting ZnO-Al2O3 interaction. We have introduced a simple method based on diffuse reflectance spectroscopy with a potential to predict furfural conversion over Zn-Al mixed oxides in aldol condensation of furfural with acetone.

This paper combines traditional ceramics with advanced ceramics, based on the principle of matching the phase separation temperature of the Na2O–B2O3–SiO2 glass system with the crystallization temperature of TiO2, and uses the melting-phase separation method to directly separate the TiO2 photocatalytic material from the porous glass. The catalyst is tightly combined with the SiO2 carrier, and then the β-FeOOH/TiO2/SiO2 composite material is prepared by the hydrothermal method. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), infrared spectroscopy (FT-IR) and specific surface area (BET) were used to analyze the crystal structure, morphology and phase composition of the compound. Ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence spectroscopy (PL) are used to characterize the light absorption characteristics of samples. Using tetracycline hydrochloride as a simulated degradation product, the photocatalytic activity of the composite photocatalyst under visible light was studied. The experimental results show that the double-crystal phase glass-ceramics are prepared by the melting phase separation method, the crystal phase is TiO2, and the amorphous phase is SiO2. A heterojunction was successfully constructed between β-FeOOH and TiO2, which effectively improved the migration efficiency of photogenerated carriers and extended the light response range to 640 nm. The photocatalytic efficiency of 0.2β-FeOOH/TiO2/SiO2 composite photocatalyst to tetracycline hydrochloride (TC) is 77 %. After 3 cycles of photocatalytic degradation test, the composite material still maintains good photocatalytic performance, and the crystal structure has not changed. Superoxide free radicals are the main active substance that degrades TC. This provides a reference for the industrial production of glass-phase TiO2-based composite photocatalyst.

In this paper, BiVO4-Cu2O nanocomposites have been synthesized by a mechano-thermal method with a controlled composition of Bi2O3, V2O5 and Cu2O contents. The effects of milling time, heat treatment temperature and composition on the structure and microstructure of the prepared samples were studied. The optical properties and photocatalytic performance of the samples under visible light irradiation were studied by Diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and dye degradation. The BiVO4 and Cu2O contents in the nanocomposite were changed and the effects on the structural stability and photocatalytic performance were studied. X-ray diffraction (XRD) patterns showed that both BiVO4 and Cu2O contents were effective on the synthesis and stability of the monoclinic phase of BiVO4. Field emission scanning electron microscopy (FESEM) micrographs indicated semi-spherical nanocomposite particles with an average particle size of 100 nm. The heterostructure at the interface between Cu2O and BiVO4 was shown by Transmission electron microscopy (TEM) and proved by X-ray photoelectron spectroscopy (XPS) spectra. DRS results indicated the minimum band gap energy of 2.12 eV for BiVO4-10 wt% of Cu2O with a 10 wt% excessive V2O5 content. The PL result has shown the lowest rate of the recombination of electron-holes for this sample. Also, the maximum degradation of 97% has been obtained for methylene blue (MB) by this sample after 240 min of being irradiated in visible light region. The photocatalytic mechanism was determined using scavengers. The kinetics of MB and methyl orange (MO) degradations was compared to study the effect of pH on the photocatalytic performance.

Pure and modified mesoporous TiO2 nanoparticles with different loadings of NiO (3-20.0 wt %) were prepared through the surfactant-assisted sol-gel approach with the use of cetyltrimethylammonium bromide as a template. The optical and structural properties of different samples were examined using N2 adsorption-desorption analysis, energy-dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence (PL) spectroscopy. X-ray diffraction results confirmed the insertion of Ni2+ into the lattice of TiO2, and the crystallite size reduced remarkably after the addition of NiO. The diffuse reflectance spectroscopy spectra displayed obvious red shift in the absorption edges, and new absorption bands appeared in the visible region when NiO was added, which indicates the formation of surface defects and oxygen vacancies. The optical band gap of TiO2 reduced sharply when the contents of NiO were increased. The increase in the surface defects as well as oxygen vacancies were examined using PL spectroscopy. The photocatalytic performance of the as-synthesized samples was investigated over photodegradation of brilliant green (BG) and phenol and hydrogen generation under visible light. 10% NiO/TiO2 exhibited the highest photocatalytic efficiency. The photocatalytic activity was improved due to the creation of a p-n junction at the interface of NiO/TiO2, which efficiently promotes the separation of photogenerated electron/hole pairs and consequently enhances its photodegradation activity. According to the photocatalytic activity results, NiO contents were considered one of the most important factors affecting the photodegradation of BG and phenol and H2 evolution. Also, we discussed the mechanism of photodegradation, mineralization (total organic carbon), and photocatalytic reaction kinetics of BG and phenol.

We have investigated the transformations of colloidal Pd-Cu and Pt-Cu bimetallic alloy nanocrystals (NCs) supported on γ-Al2O3 when exposed to a sequence of oxidizing and then reducing atmospheres, in both cases at high temperature (350 °C). A combination of in situ diffuse reflectance infrared Fourier transform spectroscopy and X-ray absorption spectroscopy was employed to probe the NC surface chemistry and structural/compositional variations in response to the different test conditions. Depending on the type of noble metal in the bimetallic NCs (whether Pd or Pt), different outcomes were observed. The oxidizing treatment on Pd-Cu NCs led to the formation of a PdCuO mixed oxide and PdO along with a minor fraction of CuO x species on the support. The same treatment on Pt-Cu NCs caused a complete dealloying between Pt and Cu, forming separate Pt NCs with a minor fraction of PtO NCs and CuO x species, the latter finely dispersed on the support. The reducing treatment that followed the oxidizing treatment largely restored the Pd-Cu alloy NCs, although with a residual fraction of CuO x species remaining. Similarly, Pt-Cu NCs were partially restored but with a large fraction of CuO x species still located on the support. Our results indicate that the noble metal present in the bimetallic Cu-based alloy NCs has a strong influence on the dealloying/migrations/realloying processes occurring under typical heterogeneous catalytic reactions, elucidating the structural/compositional variations of these NCs depending on the atmospheres to which they are exposed.

Pyrochlore glass ceramics have been fabricated via in-situ crystallization under reducing conditions by both sintering and hot isostatic pressing (HIPing) as candidate wasteforms for the acidic waste biproduct of Mo-99 radiopharmaceutical production. The tailored wasteform demonstrates flexibility in the wasteform design to receive the required waste variability, it also suitably passes high-level waste performance requirement, and successfully scales to 1 kg scale with 45 wt.% waste loading. U-rich pyrochlore as the major phase was confirmed by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, with residual glass and minor secondary phases. The presence of both U4+ and U5+ valences in the wasteforms was revealed by diffuse reflectance spectroscopy. Addition of glass content had little influence on the pyrochlore composition but facilitated minor perovskite formation. The up-scaled dense, HIPed sample showed elemental releases of

In the present study, combustion technique is adopted to study the impact of Mg2+ ion doping on ZnAI2O4 nanoparticles (NPs). L-arginine is used as a fuel component. The Mg2+ ions play a pivotal role in persuading various characteristics of ZnAI2O4 NPs. Various characterization technqiues such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), high resolution scanning electron microscopy (HR-SEM), diffuse reflectance spectroscopy (DRS), Thermo-gravimetric/differential thermal analysis (TG-DTA) and vibrating sample magnetometer (VSM) were carried out in order to synthesize the nanoparticles. Single phase cubic spinel structure of ZnAl2O4 (gahnite) formation was confirmed from the XRD characterization process of the nanoparticles. Estimated average crystallite size range of 11.85 nm to 19.02 nm was observed from Debye-Scherrer. Spherical morphology with uniform distributions was observed from HR-SEM characterization images. From the band gap studies, the attained band gap values were found to lie within 5.41 eV–4.66 eV range. The ZnAl2O4 and Mg:ZnAl2O4 NPs exhibited super-paramagnetic nature confirmed by magnetic measurements. The obtained results make ZnAl2O 4and Mg:ZnAl2O4 NPs appropriate for various optical, catalytic, energy and data storage applications.

Photocatalytic oxidation of alcohols has received more and more attention in recent years following the numerous studies on the degradation of pollutants, hydrogen evolution, and CO2 reduction by photocatalysis. Instead of the total oxidation of organics in the degradation process, the photo-oxidation of alcohols aims at the selective conversion of alcohols to produce carbonyl/acid compounds. Promising results have been achieved in designing the catalysts and reaction system, as well as in the mechanistic investigations in the past few years. This review summarizes the state-of-the-art progress in the photo-oxidation of alcohols, including the development of photocatalysts and cocatalysts, reaction conditions including the solvent and the atmosphere, and the exploration of mechanisms with scavengers experiment, electron paramagnetic resonance (EPR) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The challenges and outlook for the further research in this field are also discussed.

Herein, we report high-performance Pd and Ca-promoted Pd nanoparticles (NPs) (~2–6 nm) over mesoporous CeO2 with dual functionality of converting CO2 to methanol and its dehydration to di-methyl ether (DME) in a single catalyst bed prepared by a single-pot sol–gel chelating (SGC) method. Moreover, Ca promotion (0.5wt. %, optimized value) greatly improved the catalytic performance (XCO2: 30.5 %, SDME: 70.5 % and space time yield (STYDME): 5276 mmol/kgcat.hr at 325 °C and 20 Bar) by increasing Pd0 content over CeO2 and tuned the redox properties of CeO2 as well as basicity/acidity of tested samples as evidenced by the characterization results. In situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) provided insights of the formation of DME and CH4 with visible respective IR bands along with the identification of various transient surface species emerged over the catalyst surface at actual reaction conditions which led us to propose a reaction mechanism following a formate route to methanol and its subsequent dehydration to dimethyl ether.

White-emitting SrSc1-xLiTeO6:xDy3+ phosphors were conveniently synthesized by a conventional high-temperature solid-state synthesis process. The crystal structure, photoluminescence spectrum characteristics, fluorescence quenching phenomenon, fluorescence lifetime analysis and the thermal stability of SrSc1-xLiTeO6:xDy3+ phosphors were comprehensively illustrated. The Egap of the SrScLiTeO6 host was approximately 4.65 eV based on diffuse reflectance spectroscopy (DRS) analysis. Moreover, the SrSc0.94LiTeO6:0.06Dy3+ phosphor exhibits two principal emission bands: the narrow-band emission at 481 nm (4F9/2→6H15/2, magnetic dipole transition, blue light area) and 573 nm (4F9/2→6H13/2, electric dipole transition, yellow light area) under the excitation of 366 nm ultraviolet light, respectively. The values of τ are determined to be 0.558, 0.380, 0.307 and 0.254 ms for SrSc1-xLiTeO6:xDy3+ (x = 0.005, 0.01, 0.04, 0.08) samples, respectively. The value of ΔE for SrSc0.94LiTeO6:0.06Dy3+ phosphor is deduced to be 0.1969 eV, which indicates excellent thermal stability. In addition, the CIE coordinates are located in the white light-emitting area. The abovementioned results show that the SrSc1-xLiTeO6:xDy3+ can serve as a phosphor with potential application value for outdoor illumination.