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ZnO-coated SiO2 nanocatalyst preparation and its photocatalytic activity over nitric oxides as an alternative material to pure ZnO
摘要： Core-shell nanospheres, CSNp, consisting of silica as a core and zinc oxide as a shell were prepared via a simple and environmentally friendly procedure. Silica cores with a mean diameter of 300 nm were prepared through the hydrolysis-condensation reactions in the presence of hyperbranched poly(ethylene)imine (HBPEI) followed by calcination and chemical surface modi?cation with the use of HBPEI. To fabricate the core-shell structure, various amounts of zinc nitrate hexahydrate were precipitated using the carboxymethyl poly(ethylene)imine polymer (Trilon P) as a precipitator. To this suspension, the as synthesized modi?ed silica powder was added with the aim to develop electrostatic bonds between the carboxyl groups of TRILON P and the amino groups of the cationic HBPEI polymer. The optimization of processing parameters led to the development of homogeneous core-shell structures bearing a well-developed nanocrystalline zinc oxide shell over each silica core. The material with the optimum shell showed excellent photocatalytic activity over nitric oxides as the photocatalytic yield reached 72.9%.
关键词： Core-shell,Photocatalysis,Silicon oxide,Nitrogen oxides,Zinc oxide
更新于2025-09-04 15:30:14
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Cs-doped α-Bi2O3 microplates: hydrothermal synthesis and improved photochemical activities
摘要： Cs-doped α-Bi2O3 was synthesized via a facile hydrothermal reaction. The phase formations of the samples were investigated via X-ray powder diffraction (XRD) patterns and structural refinements. The samples present well-crystalized microplates with smooth surfaces and a thickness about 300 nm. The experiments revealed that the undoped and Cs-doped α-Bi2O3 microplates could crystallized in a pure monoclinic phase. The band gap of α-Bi2O3 could be reduced via the Cs-doping in the lattices. The photocatalytic activity on photo-degradation of methylene blue (MB) was significantly improved with the Cs-doping. The effective photocatalysis was discussed on the improved visible-light response, the enhanced dispersion in the valence band composed of hybrid orbitals of Bi6s, O2p and Cs3d, and the lowered electron–hole recombination.
关键词： Photocatalysis,Microstructures,Optical properties,Semiconductor
更新于2025-09-04 15:30:14
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Accelerated photocatalytic oxidation of carbamazepine by a novel 3D hierarchical protonated g-C3N4/BiOBr heterojunction: performance and mechanism
摘要： A novel 3D hierarchical heterojunction of protonated g-C3N4/BiOBr was fabricated by a facile precipitation method with the protonation pretreatment of g-C3N4. The material was characterized by X-ray spectrometer (SEM), transmission electron microscopic (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), UV-vis reflectance spectra (UV-Vis DRS) and Brunauer-Emmett-Teller (BET). The photocatalytic activity was systematically evaluated by the degradation of carbamazepine (CBZ) under simulated solar light irradiation. The protonated g-C3N4/BiOBr with mass ratios of 5 wt% (pgB-5) achieved the optimum performance for the CBZ removal and excellent stability. The effects of some key operating parameters were further examined in detail, including photocatalyst dosage, initial solution pH, coexisting inorganic anions (HCO3-, Cl-, NO3-). The enhanced activity was ascribed to the effective charge separation occurring at the tightly contacted interface between two phases, which was revealed by electrochemical impedance spectroscopy (EIS) and photocurrent. Basing on direct evidence of the formed hydroxyl radicals (·OH), superoxide radicals (·O2-) and holes (h+) by electron spin resonance (ESR), the photocatalytic mechanism was proposed for the charge separation. The reaction intermediates were determined by liquid chromatography coupled with mass spectrometry (LC-MS) and a tentative degradation pathway of CBZ was proposed. This study provided a new insight for the design of novel 3D hierarchical heterojunctions and the degradation of recalcitrant organic contaminants in aquatic environment.
关键词： Photocatalysis,Operation parameters,Pharmaceuticals,Wastewater treatment,Heterojunction
更新于2025-09-04 15:30:14
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Ultrathin Co0.85Se nanosheet cocatalyst for visible-light CO2 photoreduction
摘要： Ultrathin Co0.85Se nanosheets were prepared via a facile solvothermal method, which successfully overcome the disadvantage of insu?cient active sites in bulk Co0.85Se by reducing its thickness into the atomic scale. Co0.85Se nanosheets have been found to be e?cient cocatalysts for photocatalytic CO2 reduction with TON as high as 58 in 1 h reaction under visible-light irradiation. Compared with bulk Co0.85Se blocks, the ultrathin nanosheet samples exhibited nearly 2.5 times higher activity in CO2 photoreduction. The metal-like character and ultrathin 2D structure of Co0.85Se nanosheets support the superb charges transfer and rich CO2 adsorption sites exposure for surface catalysis. A relationship between the surface structure and the cocatalytic activity was established. These results not only demonstrate the potential of a notable, a?ordable and earth-abundant CO2 photoreduction cocatalyst based on ultrathin Co0.85Se nanosheets but also provide a guidance in the exploration of excellent active and durable cocatalysts/catalysts to replace noble metals for arti?cial photosynthesis.
关键词： Photocatalysis,Cocatalyst,Co0.85Se nanosheets,CO2 reduction
更新于2025-09-04 15:30:14
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Revisiting structural and photocatalytic properties of g-C3N4/TiO2: Is surface modification of TiO2 by calcination with urea an effective route to “solar” photocatalyst?
摘要： g-C3N4/TiO2 derived from the surface modification of TiO2 by calcination with urea has been widely studied as a “visible-light-active” photocatalyst for environmental purification applications. However, few attentions have been paid to the structure characterization and the photocatalytic properties of the resultant nanocomposite photocatalysts under a practical sunlight irradiation. Here we employ various characterization techniques, including TGA, XRD, TEM, XPS, UV-Vis spectrum, and N2-sorption analysis to characterize the evolutions in phase crystal structure, microstructure and optical properties of g-C3N4/TiO2 nanohybrids synthesized through calcining a mechanical mixture of urea and Evonik Aeroxide P-25 TiO2 (P25) at 350-500 oC. The thermal pyrolysis of urea leads to the surface decoration of TiO2 with graphitic carbon nitrate (g-C3N4) at temperatures above 400 oC. The photocatalytic properties of the resultant g-C3N4/TiO2 nanoparticles are evaluated through photocatalytic decoloration of methylene blue (MB) and reduction of Cr(VI) to Cr(III) under visible (420 nm), UV (365 nm), and simulated solar light irradiations. The nanohybrid photocatalysts, as most previous studies reported, show much higher photocatalytic activity under visible light irradiation than the single-component counterparts, i.e. P25 or g-C3N4. However, under solar and UV irradiation, no considerable improvements are found, which is caused by the decrease in redox potential upon interfacial charge carrier transfer between g-C3N4 and TiO2. Moreover, g-C3N4/TiO2 shows an ultralow photocatalytic activity in Cr(VI) reduction. The surface modification with organic g-C3N4 is assumed to tune the surface properties (e.g. hydrophilicity) of TiO2. Our results demonstrate that photocatalytic activity in UV range is as important as that in visible range, and developing efficient “solar” photocatalysts should balance both since they might be incompatible with each other.
关键词： graphitic carbon nitrate,dye degradation,TiO2 nanoparticles,Cr (VI) reduction,semiconductor photocatalysis,Aeroxide P25,charge carrier transfer
更新于2025-09-04 15:30:14
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Hydrothermal synthesis of flower-like Na-doped α-Bi2O3 and improved photocatalytic activity via the induced oxygen vacancies
摘要： Na-doped α-Bi2O3 with a hierarchical flower-like shape was successfully prepared via a facile hydrothermal reaction. The samples consisted of well-crystalized nanoplates with smooth surfaces and a thickness of tens of nanometers. The phase formation was investigated via X-ray powder diffraction (XRD) patterns and structural refinements. The formations of oxygen vacancies were verified and its effects on the optical and photocatalysis were discussed. The band gap of α-Bi2O3 was narrowed via forming the local energy levels by oxygen vacancy defect complexes in the lattices. The photocatalytic activities on photo-degradation of Rhodamine B (RhB) were significantly improved. The effective photocatalysis was discussed on the improved visible-light response, band structure, and dynamic luminescence decay. The photocatalysis of Na-doped α-Bi2O3 was improved via the induced oxygen vacancies. The reported hydrothermal synthesis was advantageous approach to prepare α-Bi2O3 by considering the simplicity, low reaction temperature, no post-sintering, without using any template or surfactant, large-scale production, low cost, etc.
关键词： Photocatalysis,Semiconductor,Hydrothermal synthesis,Optical properties,Oxygen vacancies
更新于2025-09-04 15:30:14
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Sulfated TiO2/WO3 nanocomposite: An efficient photocatalyst for degradation of Congo red and methyl red dyes under visible light irradiation
摘要： TiO2/WO3 nanocomposites (NCs) were successfully prepared by ultrasonic-assisted sol-gel method and acid functionalized (sulfated) by using chlorosulfonic acid. Various physicochemical properties of as prepared NCs were studied by using X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy with energy dispersive analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, UV visible diffused reflectance spectroscopy, and Brunauer-Emmett-Teller (BET) surface area analysis. It was confirmed that the active sulfonic groups are anchored onto the surface of binary NCs. Furthermore, the photocatalytic performance of this material was significantly higher for the degradation of Congo red and methyl red dyes. Both these azo dyes were degraded only within 120 min. under visible light irradiation. Recyclability of this catalyst was also studied and it was found that even after five consecutive cycles the introduced catalyst retain its catalytic efficiency above 90 %.
关键词： Photocatalysis,Sulfated TiO2/WO3,Methyl red,Nanocomposites,Congo red
更新于2025-09-04 15:30:14
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Carbonyl linked carbon nitride loading few layered MoS2 for boosting photocatalytic hydrogen generation
摘要： Pristine graphitic carbon nitride g-C3N4 materials, as a novel metal-free photocatalyst with moderate activity, have attracted intense interest. However, its fast photogenerated carriers recombination always induces a relative low performance. Herein, we for the first time report one new =C=O group linked g-C3N4 (CO-C3N4) through CO2-assisted thermal polymerization of urea. It is found that the edge =C=O groups work as the photogenerated electrons collection sites, and then promote the carriers separation. The visible-light phototatalytic hydrogen evolution performance of our synthesized samples shows 1.85 times higher than that of the reference g-C3N4. To get a considerable visible-light driven photocatalytic hydrogen generation, a new few layered MoS2 with a small size (ca. 20 nm) is prepared through a liquid exfoliation, and then is loaded onto the CO-C3N4. The optimal MoS2/CO-C3N4 sample gives the photocatalytic hydrogen evolution of 1990 and 1440μmol/(g*h) under the λ > 400 and λ > 420 illumination, higher than the reported values in literatures. The sample also shows a considerable excellent photocatalytic activity of 44.3 μmol/(g*h) under LED-600 condition.
关键词： water splitting,CO-C3N4,MoS2,photocatalysis,H2 generation
更新于2025-09-04 15:30:14
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Au-loaded porous g-C<sub>3</sub>N<sub>4</sub> nanosheets for enhanced photocatalytic IPA degradation under visible-light irradiation
摘要： A series of Au-loaded porous g-C3N4 nanosheets were prepared by anchoring Au nanoparticles onto g-C3N4 surfaces. The as-prepared samples were characterized via XRD, FTIR, TEM, BET, PL, and UV-visible measurements, respectively. The activities of Au/g-C3N4 composites were evaluated by the photocatalytic degradation of gaseous isopropyl (IPA) under visible-light illumination. The results indicated that 2% Au/g-C3N4 exhibited the highest photocatalytic efficiency of gaseous IPA oxidation (11.51 ppm/min), which was 2.4 times higher than that of pure g-C3N4 nanosheets. The remarkable photodegradation efficiency derived from the promoted photoinduced carriers separation and larger specific surface area. For one thing, the ultrathin mesoporous g-C3N4 nanosheets provided abundant reactive sites and facilitated electron diffusion. For another, the localized surface plasmon resonance (LSPR) and electron-sink effect of Au particles significantly suppress the recombination of the photoinduced holes and electrons. Therefore, the deposition of Au nanoparticles with porous g-C3N4 nanosheets could be regarded as an efficient way to enhance the photocatalytic activity of gaseous IPA pollutant removal.
关键词： nanosheet,photocatalysis,g-C3N4,Au loading,IPA
更新于2025-09-04 15:30:14
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Synthesis, Characterization and Photocatalysis of Mesoporous TiO2
摘要： The mesoporous TiO2 nanoparticulate has been prepared by evaporation induced self-assembly method using EO-PO type polyether P123 as a template. The small angle X-ray diffraction, wide angle X-ray diffraction, high-resolution transmission electron microscopy and N2 isothermal adsorption-desorption are used to study the microstructure and morphology of the as-synthesized mesoporous TiO2. The results demonstrate that the mesoporous TiO2 belongs to anatase and the size is 20-30 nm. The sample is prepared using P123 as a template with average pore size distribution of 11.54 nm, specific surface area of 84.83 m2/g and pore volume of 0.234 cm3/g. The as-synthesized mesoporous TiO2 exhibits remarkably high photocatalytic activity of 93.6 % in decomposing formaldehyde under ultraviolet light irradiations for 90 min. This work provides a basic experimental process for the preparation of mesoporous TiO2, which will possess a broad prospect in terms of the applications in improving indoor air quality.
关键词： Photocatalysis,Evaporation induced self-assembly,Mesoporous TiO2,Formaldehyde
更新于2025-09-04 15:30:14