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s Flower-like BiOI and Bi5O7I photocatalysts were synthesized by a microwave-assisted solvothermal process and then calcined at various temperatures. The effects of calcination temperature on the phase structure, crystal property, morphology, color, optical property, and activity of the photocatalysts were investigated. As the calcination temperature increased, a blue shift was observed in the diffuse reflection spectra and the band gap increased. After the calcination treatment at 500 °C, the XRD, Raman spectra, and TEM results confirmed that BiOI transformed to Bi5O7I. Although flower-like microspheres still existed, the shapes of building blocks changed from lamellar nanoplates to thick twisted stripes when the BiOI transformed to Bi5O7I. BiOI with a calcination treatment at 300 °C exhibits an improved H2 production activity of 1373 μmol g−1 h−1. The XRD spectra reveal that the B-400 photocatalyst was a Bi5O7I-rich and BiOI-deficient composite material. Fewer Bi5O7I–BiOI interfaces and lower light absorption may be the reasons why the B-400 photocatalyst with Bi5O7I–BiOI compositions did not exhibit higher activity than B-300 (pure BiOI) and B-500 (pure Bi5O7I) photocatalysts.

In this study, Ni/Al2O3 was prepared with an impregnation method for CO2 hydrogenation into carbon nanofibers (CNFs). High purity CNFs were acquired from CO2 hydrogenation at 500 °C and 1 atm over Ni/Al2O3 catalyst after a liquid phase extraction process, removing the used catalysts and by-products. The particle properties of as-prepared Ni/Al2O3 have been well characterized for comparison with the commercial ones. The results of XPS spectra and XRPD patterns indicated that the commercial, as-prepared, and used Ni/Al2O3 were multicomponent with various crystal phases. The as-prepared Ni/Al2O3 can be sufficiently exposed in CO2 atmosphere for higher catalytic performances owing to its unique microstructure with higher specific surface area (429.2 m2/g). Both EXAFS and XANES spectra have shown that the first shell of Ni atom in commercial, as-prepared, and used Ni/Al2O3 were Ni O with bond distances of 1.61, 1.63, and 1.62 A, respectively. The configuration of fabricated CNFs was characterized by its unique ID/IG (Intensities of D-band/G-band) ratio of 0.23 in the Raman spectrum. Solid tubular shape with 30 nm diameter of CNFs was observed using FE–SEM and HR–TEM. Thermodynamic analyses indicate that CO2 hydrogenation into CNFs is a spontaneous and exothermic reaction with an optimal temperature of 500 °C.

The performance of an electrochemiluminescence (ECL) immunosensor was improved with a particle gradient. SiO

ZnO@ZnS nanorod-decorated Ni foam was prepared as a self-supported photocatalyst for hydrogen generation through a two-step method, including the formation of the ZnO nanorod core by a hydrothermal method, and the fabrication of the ZnS shell by a sulfidation method. The impact of the ZnS shell thickness was studied, including the influence on the optical properties, surface wettability, separation of photoexcited charge carriers, and photocatalytic hydrogen generation performance. Formation of the core-shell ZnO@ZnS structure and the incorporation of the conductive Ni foam substrate can enhance the separation of photoexcited carriers of the immobilized photocatalyst. The formation of ZnO@ZnS nanorods on the Ni foam resulted in a change in the surface from hydrophobic to superhydrophilic. The porous texture of the Ni foam facilitates the effective contact between the sacrificial agent and the immobilized photocatalyst. The ZnO@ZnS/Ni foam photocatalyst that was synthesized using a sulfidation time of 4 h, (namely, NZS4), exhibited H2 generation activity of 5860 μmol g−1 h−1, which is approximately three-fold that of the ZnO/Ni foam photocatalyst (named NZ). After being reused for three cycles, with a simple washing between cycles, the NZS4 photocatalyst retained 90% of its hydrogen generation activity.

Magnetically stirrable photocatalysts binding the ZnS-decorated Ni foam with the metal complex cocatalyst as a redox mediator and light-absorbing composition were investigated. Loading metal complex can improve light absorption, surface hydrophilicity, interfacial charge migration, and H

In the current study, heterostructured Ag@AgCl@AgI nanotubes were synthesized via an anion-exchange reaction between Ag@AgCl nanotubes and I− anions. Moreover, their photocatalytic performance towards the decontamination of dye contaminants were examined. These prepared photocatalysts were accordingly characterized using high-resolution scanning electron microscopy (HR-SEM), XRPD, XPS, field-emission transmission electron microscopy (FE-TEM), and photoluminescence (PL) spectroscopy. The structural identification analyses confirmed that the photocatalysts had nanotubular morphology. Compared to polyhedral Ag@AgI nanocomposites, the amalgamation of I− ions into the Ag@AgCl framework extraordinarily improved the photocatalytic performance. The synthesized Ag@AgCl@AgI nanotubes can also be reused due to their high stability. Under visible-light irradiation, >91.8% of Rhodamine B (RhB) was degraded within 45 min using the catalyst AI–2 (Cl−/I− = 1:1). The radical trap experiments indicated that the photodegradation of RhB was driven by the participation of superoxide radical and the action of holes. Due to the surface plasmon resonance effect, the photocatalyst AI–2 demonstrated higher photocatalytic performance, enhanced surface area and photoelectron transfer, which is also ascribed to its unique heterostructured configuration.

This study has evaluated the efficiency of zero-valent iron nanoparticles (nZVI) for the remediation of soil and groundwater containing 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). It was conducted via different treatment methods (batch experiments, column tests, and a permeable reactive barrier (PRB)) system. The combinative studies could be used to develop a more effective remediation technique. The chemical reactions that occurred upon mixing nZVI and contaminants provided the batch experiments, leading to rapid reduction of the explosives. There was a decrease in the removal efficiency from 95% to less than 30% for the batch experiments, which was due to the lake of stirring facilities in the column test, PRB system, and the interaction of the soil and explosives with nZVI. Kinetics studies indicated a more significant and rapid degradation of TNT than that of RDX and HMX, which was consistent with the lower activation energy of TNT. The X-ray spectroscopy results highlighted that during the reduction process, nZVI was transformed into core-shell structures with Fe(0) core and Fe3O4 shell. High-performance liquid chromatography-mass spectrometry (HPLC/MS) tests depicted the decomposition of explosive contaminants into simple elements, such as carbon dioxide, nitrous oxide, and methane, over cleavage of the ring structure.

Effective water use is currently a critical global challenge needed to prevent water shortages and has attracted significant research attention. The realization of solar-driven water evaporation by using effective converters has attracted considerable attention in recent years owing to its potential for seawater desalination and wastewater treatment. Consequently, this paper proposes a simple two-step method to prepare low-cost and self-floating photothermal converters from waste coffee grounds. First, the coffee grounds were carbonized at 1,000 °C to develop broadband absorption, and the carbonized coffee grounds were modified using hydrophobic silane to enhance the water-floatation property of the grounds. The prepared hydrophobic carbonized coffee grounds exhibited good performance for desalination and water purification under sunlight irradiation. The self-floatation ability, low cost, well solar evaporation performance, and easy preparation contribute to the promising potential of using hydrophobic carbonized coffee grounds infuture steps toward eco-friendly desalination procedures.

Gelatin was immobilized selectively on the amide groups-modified bottom of a trench array of a photoresist template with 2 μm resolution by the ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide reaction. The gelatin-immobilized line array was brominated to generate a macroinitiator for atom transfer radical polymerization. Poly(methacrylic acid) (PMAA) brushes were grafted from the macroinitiator layer as line arrays of one-dimensional diffraction gratings (DGs) for various grafting polymerization times. A laser beam system was employed to analyze the optical feature with a characteristic diffraction effect of the PMAA DGs at a 45° incident angle along the transverse magnetic and transverse electric polarization. The growth of the PMAA brush lines increased both their heights and widths, leading to a change in the reflective diffraction intensity. The PMAA brushes under various grafting polymerization times were cleaved from the substrate by digestion of gelatin with trypsin, and their molecular weights were obtained by gel permeation chromatography. The change degree of the diffraction intensity varied linearly with the molecular weight of the PMAA brushes over a wide range, from 135 to 1475 kDa, with high correlation coefficients. Molecular weight determination of polymer brushes using the reflective diffraction intensity provides a simple method to monitor their growth in real time without polymer brush cleavage.

Bismuth vanadate (BiVO4), W-doped BiVO4 (BiVO4:W), and Mo-doped BiVO4 (BiVO4:Mo) nanoparticles were synthesized at pH = 4 using a green hydrothermal method. The effects of 2 at% W or Mo doping on the microstructural and optical characteristics of as-prepared BiVO4 nanoparticles and the effect of combining particle morphology modification and impurity dopant incorporation on the visible-light-derived photocatalytic degradation of dilute Rhodamine B (RhB) solution are studied. XRD examination revealed that these obtained BiVO4-based nanoparticles had a highly crystalline and single monoclinic phase. SEM and TEM observations showed that impurity doping could modify the surface morphology, change the particle shape, and reduce the particle diameter to enlarge their specific surface area, increasing the reactive sites of the photocatalytic process. XPS and FL measurements indicated that W- and Mo-doped nanoparticles possessed higher concentrations of oxygen vacancies, which could promote the n-type semiconductor property. It was found that the BiVO4:W and BiVO4:Mo powder samples exhibited better photocatalytic activity for efficient RhB removal than that shown by pristine BiVO4 powder samples under visible light illumination. That feature can be ascribed to the larger surface area and improved concentration of photogenerated charge carriers of the former.

Stainless steel wire mesh/bismuth oxybromide (BiOBr) were synthesized as immobilized photocatalysts. The effects of conductive wire mesh substrate and calcination on the photocatalytic performance were investigated. The morphology, crystal structure, composition, and optical properties of hierarchical wire mesh/BiOBr photocatalyst were investigated. The degradation of 99% dye can be achieved within 50 min by S250 photocatalyst which was calcined at 250 °C. The recycled photocatalyst also shows good stability. The activity of the immobilized photocatalysts was enhanced by increasing the surface area (flower-like texture of BiOBr), facilitating separation of photogenerated charge carriers (good contact between BiOBr and conductive stainless steel wire mesh), and improving the crystal properties (facet effect, dominant (001) facets by calcination). This study provides a way to optimizing the activity of immobilized photocatalysts for the treatment of hazardous pollutants in wastewater.

Free-standing carbon nanotube films (CNTF) with entangled carbon nanotubes (CNT) were used as conductive supports for the preparation of CuS–ZnS/CNTF composite as immobilized photocatalysts for H2 production. The surface morphology, crystalline property, surface chemistry, and optical properties of the CuS–ZnS/CNTF photocatalysts were investigated. The effects of forming CuS–ZnS heterojunction and conductive CNTF on the separation of photogenerated charges and photocatalytic hydrogen production activity of CuS–ZnS/CNTF photocatalysts were evaluated by the photocatalytic hydrogen production tests. Conductive CNT films can prevent the recombination of photogenerated electron–hole pairs. The deposition of CuS nanoparticles on the ZnS/CNTF leads to higher photocatalytic activity which can be attributed to the effective electron–hole separation. Introducing ZnS and CuS makes the photocatalyst surface more hydrophilic. The porous structure contributed to the effective contact between the sacrificing agents and the photocatalysts, leading to enhanced H2 production activity.

Ni-doped ZnS nanomaterials were decorated on the surfaces of porous Ni foam as immobilized photocatalysts for H 2 production by a solvothermal process. Effects of the Ni dopant content on the photocatalytic hydrogen production activity, morphology, optical property, crystalline properties, surface wetting, and photocurrent were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescence (PL), photocurrent response, and contact angle meter. The surface changed from hydrophobic to superhydrophilic by decorating Ni-doped ZnS on the NiO/Ni foam substrate. A mechanism is proposed to elucidate the band positions of ZnS and NiO, together with the transfer of photoinduced electrons among ZnS, NiO, and Ni foam. The Ni-doped ZnS/NiO/Ni foam photocatalyst NZ5 showed much higher photocatalytic activity because of the matched band structure and the high conductivity of Ni foam. Meanwhile, the porous texture and superhydrophilic nature of the photocatalyst favor the light trapping, effective mass transfer of reactant molecules, and provide large contact area. Ni doping leads to a decreased band gap. The highest photocatalytic H 2 generation activity reached 2500 μmol/g −1 h −1 . After being operated for 3 cycles, the activity of the third run was 85% of that obtained at the first run.

CuS nanoparticles were decorated on Fe3O4@ZnS particles for the synthesis of magnetically separable photocatalysts with magnetic Fe3O4 core, together with heterojunction interfaces between ZnS and CuS. The electron-hole spatial separation ability and photocatalytic activity can be improved by optimizing the amount of CuS grown on ZnS. The highest photocatalytic H2 generation activity of the Fe3O4@ZnS CuS photocatalyst reached 18000 μmol/g−1 h−1. The crystalline property, morphology, optical property, photocurrent response, magnetic performance, photocatalytic performance, and separation property of the composite photocatalysts were investigated. The photocatalysts can be separated and recycled by a magnet. A mechanism of photocatalytic H2 generation by the Fe3O4@ZnS CuS photocatalysts was proposed. The recombination of photoexcited electron and hole was suppressed by such kind of electron transfer, leading to the enhanced activity of the Fe3O4@ZnS CuS photocatalysts.

It is still a challenging task to make a colorimetric sensor which can respond to multiple responses at the same time. This task is even more difficult in aqueous solutions, as water molecules will significantly interfere the sensing process. Therefore, we have designed the low-cost, simple, efficient and selective dual responsive chemical sensor (DRCS) by capping the aniline trimer with benzoyl isothiocyanate. This sensor combines the advantages of naked eye detection of the CN¯ ion at different pH values. Moreover, DRCS can detect the pH of mixed solvent (DMSO/H2O) by the naked eye. The DRCS has shown high sensitivity to CN¯ ions. Meanwhile, it has no obvious response to other interfering anions, such as F¯, AcO¯, Br¯, HSO4¯, SCN¯, PO43¯, I¯, ClO4¯, Cl¯, NO3¯, PF6¯, and BF4¯. A minimum detection limit of 0.2 μM was achieved by DRCS for CN¯ ions. The feasibility of on-site detection of CN¯ was demonstrated using DRCS coated filter paper stripes. The present study reveals that the DRCS as low-cost material can be used as a potential sensor for the selective sensing of CN¯ ions and pH in the solutions.

BiOI-based photocatalysts were proved to exhibit photocatalytic H2 production activity. AgI-BiOI-graphene showed better H2 production activity than BiOI and BiOI-graphene. The surface chemistry, electronic property, phase structure, morphology, optical property and photocatalytic performance of these photocatalysts were studied. The interfacial electronic states of the photocatalysts were investigated through their C K-edge near-edge X-ray-absorption fine-structure (NEXAFS) spectra. Based on the in situ NEXAFS spectra measured with and without illumination, a mechanism about the transport of photoelectron from AgI to graphene through BiOI is proposed for the photocatalytic H2 production process. The incorporation of graphene restricted the three-dimensional self-assembly of BiOI nanocrystals and led to the formation of less extensively crystallized BiOI domains through a confined-space effect. Addition of AgNO3 precursor altered the crystal structure of BiOI from flower-like to horizontally stacked flat plates. The results of NEXAFS spectra, photoluminescence spectra and photocurrent tests reveal that the improved photocatalytic activity of the AgI-BiOI-graphene photocatalyst is attributable to the interfacial interaction among AgI, BiOI and graphene, which enhanced the separation of photogenerated electrons to generate H2. AgI-BiOI-graphene photocatalyst was a stable photocatalyst for the production of H2. After three cycles, 86% activity of recycled photocatalysts was retained.

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A new efficient Schiff base sensor SB3 for fluorescent and colorimetric “naked-eye” “turn-on” sensing of cyanide anion (CN–) with excellent sensitivity and selectivity was developed. The 4,4'-(perfluoropropane-2,2-diyl)bisphenol group and two phenyl groups were covalently linked by two C = N bonds to extend the conjugation length. The four hydroxyl groups can improve the water solubility of the SB3 sensor. The SB3 sensor exhibited high specificity towards CN− by interrupting its intramolecular charge transfer, resulting in a color change and remarkable “turn-on” green fluorescence emission. The sensing mechanism is caused by the nucleophilic addition of CN– toward imine groups of the SB3 sensor, leading to breaks of the conjugation, fluorescent spectral changes, and color change. It was confirmed by 1H NMR titration and Mass spectra. The detection limits for CN– and Al3+obtained by fluorescence spectrum are 0.80 µM and 0.25 µM, respectively. The SB3 sensor can act as an efficient chemical sensor for detecting the CN– and Al3+ ions under common environmental and physiological conditions (pH 5–12). Besides, the sensor can also detect CN− in food materials (such as sprouting potatoes and cassava flour) and imaging CN− in living cells with strong “turn-on” fluorescence at 490 nm. SB3 is an excellent CN– sensor that exhibits some advantages, including easy synthesis, distinct fluorescence and color change, high selectivity, low detection limit, and good anti-interference ability to analyze solution and food samples, together with fluorescence cell imaging.

The development of fluorescence molecules for the fast and effective detection of L-tryptophan (L-Trp) has attracted a lot of attention because it is an important amino acid for baby growth, nitrogen equilibrium in adults, improving sleep, and mood regulation. A dimedone-phenylalanine-based chiral sensor (SDPA) was synthesized and exhibited a strong fluorescence quenching by Fe

It is crucial to remove heavy metals and dyes before discharging industrial effluents. Gauze substrate was surface-modified by coating with a polymeric adsorbent and a spray coating of BiOBr photocatalyst to develop a novel dual-functional membrane, polymer/BiOBr-modified gauze, for water remediation. The polymeric adsorbent was crosslinked to prevent the dissolving of the adsorbent during operation in contaminated water. The morphology and surface chemistry of the modified gauze were characterized before and after the adsorption of Ni2+. The surface wettability, isotherms, and kinetics of Ni2+ adsorption were studied. We also studied the effect of pH, initial Ni2+ concentration, monomer molar ratio, and monomer chemical structure on the Ni2+ adsorption capacity. To achieve a high Ni2+ adsorption capacity and good photocatalytic decolorization activity, the amount of decorated BiOBr was tuned by changing the spray-coating time to optimize the exposed BiOBr and polymer on the surface. The optimized dual-functional membrane PB20 possesses excellent adsorption capacity (650 mg g&minus, 1) for Ni2+ ions and photocatalytic decolorization activity (100% degradation of RhB within 7 min). Decorating the optimized amount of BiOBr on the surface can introduce photocatalytic decolorization activity without sacrificing the adsorption capacity for Ni2+.

The detection of metal ions and amino acids by the aniline oligomer-based receptor has not been reported yet, to the best of our knowledge. In this study, an efficient multifunctional cation-amino acid sensor (CAS) with aniline moiety and chiral thiourea binding site was synthesized by the reaction of aniline trimer and (S)-(+)-1-phenyl ethyl isothiocyanate. CAS can sense Fe

This study describes an effective method for the removal of nickel ions (Ni2+) from the water by repetitive absorption and regeneration (desorption) cycles using immobilized adsorbents. Polyethyleneimine (PEI) based epoxy coated gauzes having the high density of active sites were prepared as immobilized adsorbents. The adsorption of Ni2+ by the PEI based epoxy coated gauze was confirmed by the analysis of the immobilized surface using X-ray photoelectron spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The effects of type of the cross-linking agents and PEI/cross-linker molar ratio on the adsorption efficiency were studied. The surface wettability of the immobilized adsorbent was evaluated using dynamic contact angle measurements. The adsorption behaviors can be fitted with the Freundlich isotherm and the pseudo-second-order kinetic model. The adsorption of the Ni2+ was studied at various treatment time and pH. Because of the porous structure and large surface area of the gauze based adsorbent, together with the large amount of oxygen atoms and amine groups on the molecular chain of adsorbent, the optimized adsorption capacity for Ni2+ can reach 650 mg/g. More importantly, the adsorbent has retained its adsorption capability even after repeated adsorption-desorption cycles.

The geometry of resonant absorbers (RA) is varied by tryptic digestion to design a probe platform. The process includes fabrication of a line array of poly(methacrylic acid) (PMAA) brush as an RA, tailed by the immobilization of gelatin. The gelatin-modified PMAA RA is a kind of one-dimensional plasmonic grating, possessing an optical feature with a characteristic absorption peak. The growth of gelatin on PMAA RA resulted in a blue shift of the absorption peak from 465 to 263 nm. Trypsin catalyzes the hydrolysis of peptide bonds, breaking down gelatin into smaller peptides causing the change in geometry of RA. The gelatin of RA was digested in a wide linear range of activity of trypsin from 34 to 1088 U mL−1 resulting in a red shift of the absorption peak of RA from 263 to 474 nm within 10 min. The limit of detection achieved is 11 U mL−1 with ca. 1.9% standard deviation and 101.4% recovery of spiked serum samples. The chemical selectivity of the trypsin assay is evidenced by motoring the changes in a shift of the absorption peak of gelatin-modified PMAA RA using chymotrypsin and horseradish peroxidase.

Although there is significant progress in the research of carbon dots (CDs), some challenges such as difficulty in large-scale synthesis, complicated purification, low quantum yield, ambiguity in structure-property correlation, electronic structures, and photophysics are still major obstacles that hinder the commercial use of CDs. Recent advances in synthesis, modification, characterization, and applications of CDs are summarized in this review. We illustrate some examples to correlate process parameters, structures, compositions, properties, and performances of CDs-based materials. The advances in the synthesis approach, purification methods, and modification/doping methods for the synthesis of CDs are also presented. Moreover, some examples of the kilogram-scale fabrication of CDs are given. The properties and performance of CDs can be tuned by some synthesis parameters, such as the incubation time and precursor ratio, the laser pulse width, and the average molar mass of the polymeric precursor. Surface passivation also has a significant influence on the particle sizes of CDs. Moreover, some factors affect the properties and performance of CDs, such as the polarity-sensitive fluorescence effect and concentration-dependent multicolor luminescence, together with the size and surface states of CDs. The synchrotron near-edge X-ray absorption fine structure (NEXAFS) test has been proved to be a useful tool to explore the correlation among structural features, photophysics, and emission performance of CDs. Recent advances of CDs in bioimaging, sensing, therapy, energy, fertilizer, separation, security authentication, food packing, flame retardant, and co-catalyst for environmental remediation applications were reviewed in this article. Furthermore, the roles of CDs, doped CDs, and their composites in these applications were also demonstrated.

We report a graphene embedded organic-inorganic hybrid (O-I hybrid) composites that can be utilized as robust encapsulants for white light emitting diodes (WLEDs). The effect of graphene and monomers on the thermal resistance, refractive index (RI), transparency, thermal conductivity, and thermal aging stability of the encapsulant were studied. This study has explicitly unveiled that the embedded graphene played a multifunctional role in producing a high-performance encapsulant. Compared with graphene free O-I hybrid encapsulant, RI, thermal conductivity and heat dissipation ability of the graphene embedded encapsulants were significantly improved. After continuous operation for 10 days, the color rendering index (Ra) of WLED with graphene embedded encapsulants changed from 89.5 to 89.2 (driving current 100 mA), while the correlated color temperature (CCT) altered from 4535 to 4546. Its luminous efficiency changed from 82.9 to 81.2 lm/W. The WLEDs with graphene embedded O-I hybrid encapsulant exhibited long-term stability. This work has paved the way for rational design and assembly of graphene embedded composites as robust materials for various requirements of WLED applications.

Glycerol is a byproduct of biodiesel manufacturing. The room temperature photocatalytic hydrogen generation from glycerol by the ZnO-ZnS/graphene photocatalyst was investigated. The in-situ C K-edge near edge X-ray absorption fine structure (NEXAFS) spectra were measured with/without light illumination to study the electronic properties of photocatalysts at atomic and molecular level. A mechanism of water splitting and glycerol oxidation/reforming reactions over the photocatalyst under light irradiation is proposed. Effects of graphene content in photocatalysts and glycerol concentration in solution on the photocatalytic activity were examined. The results of enhanced photocurrents, fluorescence quenching, NEXAFS spectra, and decreased arc radius of electrochemical impedance spectra of ZnO-ZnS/graphene photocatalysts revealed the fast transfer of photoexcited electrons from ZnO-ZnS nanoparticles to graphene. There was an optimal graphene content and a glycerol concentration for the maximum photocatalytic H2 production rate (1070 μmol h−1 g−1). Incorporation of graphene can enhance the separation of photogenerated charge through the ZnO-ZnS/graphene interfaces and improve the photocatalytic H2 production rate of the photocatalysts. The composite photocatalysts exhibited improved performance because of efficient charge separation and enhanced light absorption.

A low operating temperature CO (carbon monoxide) sensor was fabricated from a nanometer-scale SnO2 (tin oxide) powder. The SnO2 nanoparticles in a size range 10–20 nm were synthesized as a function of surfactant (tri-n-octylamine, TOA) addition (0–1.5 mol%) via a simple thermal decomposition method. The resulting SnO2 nanoparticles were first screen-printed onto an electrode patterned substrate to be a thick film. Subsequently, the composite film was heat-treated to be a device for sensing CO gas. The thermal decomposed powders were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), and surface area measurements (BET). The CO-sensing performance of all the sensors was investigated. The experimental results showed that the TOA addition significantly decreased the particle size of the resulting SnO2 nanoparticle. However, the structure of the powder coating was crucial to their sensing performance. After heat-treatment, the smaller particle tended to cause the formation of agglomeration, resulting in the decline of surface area and reducing the reaction site during sensing. However, the paths for the sensed gas entering between the agglomerated structure may influence the sensing performance. As a CO sensing material, the SnO2 nanoparticle (~12 nm in diameter) prepared with 1.25 mol% TOA addition exhibited most stable electrical performance. The SnO2 coating with TOA addition >0.75 mol% exhibited sensor response at a relatively low temperature of

Ag-doped Bi2WO6-graphene based photocatalysts were found to exhibit hydrogen production activity. The performance of Bi2WO6-graphene based photocatalysts were investigated and optimized in this study. The activity can be further improved by Ag-doping. The morphology, surface chemistry, and phase structure of the photocatalysts were investigated by Field emission scanning electron microscopy, Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectra, and X-ray diffraction. UV–vis diffuse reflectance spectroscopy and zeta potential were measured to study the optical properties, bandgap and dispersion stability of the photocatalysts. The effects of forming Bi2WO6-graphene contact and Ag doping on the light absorption, band gap, dispersion stability, and photocatalytic H2 production performance of the composite photocatalysts were evaluated. The improved photocatalytic performance is mainly owing to the Ag doping and high electrical conductivity of graphene.

In this study, poly(vinyl chloride) (PVC) was electrospun into fibrous membranes and then reacted with NaN3 to generate azido-terminated PVC fibrous membranes. A propargyl-terminated poly(N-isopropylacrylamide) (PNIPAAm) was also synthesized and then grafted, through click reactions, onto the azido-terminated PVC fiber surface. Protrusion-, scale-, and joint-like structures of the PNIPAAm grafts on the PVC fibers were formed upon increasing the molecular weight of the PNIPAAm grafts. The PNIPAAm-grafted PVC fibrous mats exhibited completely wetted surfaces at 25 °C because of their high roughness. The static water contact angle of the PNIPAAm-grafted PVC fibrous mats reached 140° when the temperature was increased to 45 °C. This thermoresponsive behavior was significantly greater than that of the PNIPAAm grafted on a flat surface. Temperature-responsive membranes were constructed having a pore size of 1.38 μm and applied as protein valves to block and release an antibody (fluorescein-conjugated AffiniPure goat anti-rabbit IgG). At 25 °C, the collection efficiency remained at 94% for antibody concentrations up to 60 ng/L. As the temperature increased to 45 °C, the collection efficiency decreased abruptly, to 4%, when the antibody concentration was greater than 20 ng/L. Accordingly, this system of PNIPAAm-grafted PVC fibers functioned as a protein valve allowing the capture and concentration of proteins.

A composite photocatalyst consisting of the BiOBr/Bi2S3 heterojunction and a Cu complex exhibited high H2 production activity through an efficient transport of charge by redox couple Cu(II)/Cu(I) of the complex. BiOBr was prepared by a microwave solvothermal method. Then, the BiOBr/Bi2S3 composite was prepared as a heterojunction photocatalyst by an ion-exchange process. The copper complex was then introduced as a co-catalyst or a redox mediator. The morphology, crystal properties, optical properties, surface chemistry, photocurrent response, and photocatalytic activity of these BiOBr/Bi2S3/copper complex composites were investigated. The formation of a BiOBr/Bi2S3 heterojunction and the introduction of Cu complex improved the performance of the photocatalysts. For the first time, operando X-ray absorption spectra were recorded in situ to unveil the local interaction at the reactant-photocatalyst interface toward the photocatalysis reaction of BiOBr/Bi2S3-Cu complex photocatalyst in the sacrificial agent solution (Na2S, Na2SO3).

The dual-functional Bi2WO6/polydopamine (PDA)-modified gauze membrane has been developed for applications in photocatalytic degradation and solar steam generation. Two types of membrane were prepared by changing the growth sequence of Bi2WO6 nanomaterials and PDA on gauze substrates. The spatial distribution of Bi2WO6 and polydopamine has a great influence on light absorption, photocatalytic degradation, and solar steam generation performances. Bi2WO6 photocatalysts can absorb short-wavelength light for the photocatalytic decoloration of organic dyes. The photothermal polydopamine can convert light into heat for water evaporation. Besides, the gauze substrate provides water transport channels to facilitate water evaporation. The morphology, surface chemistry, and optical properties of Bi2WO6-PDA modified gauzes were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance spectra. The photothermal properties, wetting properties, and solar steam generation rates of the composite films were also studied. Degradation of 96% of indigo carmine was achieved after being irradiated for 120 min in the presence of G/PDA/BWNP. The water evaporation rates of the G/BWP/PDA sample under the irradiation of an Xe lamp (light intensity = 1000 W/m2) reached 1.94 kg·m−2·h−1.

Supercapacitive properties of Co/ZnCo oxide composite with a core–shell nanostructure (Co3O4/ZnCo2O4) prepared directly onto a nickel foam substrate by a two-step hydrothermal method were investigated. The synthesized core–shell structure consisted of some ∼40–100 nm in thick flaky ZnCo2O4 deposits coated onto the surface of Co3O4 nanorods measuring ∼150 nm in diameter. The specific capacitance value of the Co3O4/ZnCo2O4 core–shell nanostructure synthesized by hydrothermal at 130 °C for a ZnCo2O4 deposition time of 2 h can attain 1804 F g−1 at a scan rate of 5 mV s−1. Furthermore, the core–shell structured electrode still exhibited a relatively good capacitance retention of more than 93% after 3000 CV cycles due to the superior structural support of Co3O4 scaffolds. The Co3O4/ZnCo2O4 core–shell structure exhibits excellent electrochemical performances and, as such, is one of the more promising active materials in pseudocapacitor applications.

The main objective of the present study is to understand the structure-property relationships of sensor capable of colorimetric response, upon the addition of particular anions, due to hydrogen-bonding association between sensor and anion. Further, hydrogen-bonding association between sensor and anion, and thereby colorimetric response of the receptor in various solvent media was also targeted. For this, we have synthesized chloro-substituted quinone based oligomer sensor (QO-Cl) and cyano-substituted quinone based oligomer sensor (QO-CN), which contain the thiourea as a binding site. These oligomeric sensors were exploited as colorimetric sensors for cyanide anion [CN−]. Further, the sensing abilities of these sensors for CN− recognition in various solvents were monitored to investigate the influence of solvent on the hydrogen bonding association between sensor and anion. Our colorimetric and spectrometric results unveiled that the QO-CN sensor has shown the better binding constant (KQO-CN-CN − = 39,317 M− 1) and detection of limit (DOL = 1.2 μM) for CN− than that of QO-Cl, (KQO-Cl-CN − = 1950 M− 1; DOL = 69 μM). This can be attributed to the higher electron withdrawing nature of C N than the moderately electron-withdrawing substituent Cl.

A flower-like Bi2WO6-Bi2O3 photocatalyst was prepared by a two-step process, including an ionic liquid-assisted solvothermal step and calcination. The effects of the ionic liquids and calcination on the morphology, property, and photocatalytic performance of Bi2WO6-based photocatalysts were studied. The addition of ionic liquids during the preparation of Bi2WO6 based-materials lead to increased sizes of photocatalysts and the formation of more petal sheets in the flower-like microspheres. The results of XRD, XPS, and TEM confirm that Bi2WO6-Bi2O3 photocatalysts formed after the calcination treatment of Bi2WO6 photocatalyst in an air atmosphere. The Bi2WO6-Bi2O3 flower-like photocatalyst exhibits better photocatalytic H2 production activity than the Bi2WO6 photocatalyst. The improved activity of the Bi2WO6-Bi2O3 photocatalysts was attributed to their enhanced light absorption, increased surface area, matched band structure, and the inhibited recombination of the photogenerated charge carriers.

Sensing of F−, CN− and Ac− is important from the viewpoint of both medically and environmentally. Particularly, sensing of the anions in 100% water by a colorimetric chemical sensor is a highly difficult task as water molecules interfere the sensing mechanism. In this regard, sensor R1, having azo and nitrophenyl groups as signaling units and thiourea as a binding site was prepared. This sensor exclusively detected CN− ion over other testing anions in 30% aq. DMSO solution by exhibiting distinct spectral and visual color changes. However, in 15% aq. DMSO solution, R1 exhibited obvious spectral and color changes in response to F−, CN− and Ac−. On the other hand, we have also designed sensor, R2, having same signaling units of R1, but a different binding site of urea group. Surprisingly, in contrast to R1, R2 exhibited obvious spectral and color changes in 5% aq. DMSO solution only. Further, economically viable “test stripes” were prepared in a facile mode to detect the CN− in 100% aqueous solution. Such stripes can serve as a practical colorimetric probe for “in the field” detection of the ions and thus avoid additional expensive equipment.

Flower-like graphene (FG) prepared by a transformer coupled plasma enhanced chemical vapor deposition method was used as support for the preparation of composite photocatalysts. Small ZnS particles were formed on the surface of FG by a hydrothermal process with ZnCl2 and Na2S precursors. The surface morphology, surface area, surface chemistry, crystalline property, optical properties, photogenerated current and photocatalytic hydrogen production activity of the FG-ZnS photocatalysts were investigated by using the X-ray diffraction, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectra, photocurrent response, photoluminescence spectra, electrochemical impedance spectra and photocatalytic hydrogen production tests. The maximum hydrogen production rate of FG-ZnS composite photocatalyst ZS-G0.02 was 11600 μmol g−1h−1 under UV light irradiation at a graphene/ZnCl2 precursor weight ratio of 0.02. The flower-like structure of FG may help the light absorption, adsorption of sacrificing agents in the solution, and separation of photogenerated carriers. In comparison with pristine ZnS photocatalyst, the FG-ZnS nanocomposites exhibits enhanced photocatalytic hydrogen production activity.

A novel CuS ZnS1−xOx/g-C3N4 nanocomposites were prepared by a thermal decomposition process and a hydrothermal method. The effects of the Cu(NO3)2 dopant precursor concentration and weight ratio of g-C3N4/ZnS1−xOx on the morphology, crystalline properties, optical property, photocurrent were investigated by using the field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectra (DRS), photocurrent response, and hydrogen production tests. Decorating CuS improved the absorption of the heterostructured photocatalysts. H2 production rate was increased from 9200 to 10,900 μmol h−1 g−1 by incorporating CuS. By loading 5 wt% g-C3N4 on CuS ZnS1−xOx, the maximal hydrogen production rate of the composite catalyst reached 12,200 μmol g−1h−1 under UV light irradiation. Introducing g-C3N4 helps to separate photogenerated electron–hole pairs. After being operated for 3 cycles, the recycled CuS ZnS1−xOx/g-C3N4 photocatalyst retained 87% of its original activity.

Indeed, the relative strength of specific ion effect on macromolecule/biomacromolecules increases with increasing concentration. However, the utilization of high ion concentration may lead to aggregation or precipitation of macromolecule/biomacromolecule. Therefore, in the present study, we provided a potential alternative method to tune the strengths of “salting-in” and “salting-out” effects of Hofmeister series anions on the coil-globule transition of poly(N-isopropylacrylamide) (PNIPAM) by using a crown ether, 18-crown-6 (18-C-6) as a crowding agent. The ionic liquids (ILs) having the same cation, 1-butyl-3-methylimidazolium (Bmim+) and commonly used anions such as CH3COO−, Cl− and I− were selected to explore the strengths of “salting-in” and “salting-out” effects of Hofmeister series anions on a coil-globule transition of PNIPAM in the crowded environment of 18-C-6. Our experimental results (differential scanning calorimetry, hydrodynamic radius, fluoresce intensity, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy) demonstrated that the salting-out effect exerted by a kosmotropic anion, CH3COO−, is strengthened, while the salting-in effect exerted by a chaotropic anion, I−, is weakened in the presence of 18-C-6. The results from the present study may certainly provide an alternative method to tune the relative strength of Hofmeister effect without increasing salt concentration.