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G‐C3N4‐SiC‐Pt for Enhanced Photocatalytic H2 Production from Water under Visible Light Irradiation
摘要： The g-C3N4 and SiC has drawn increasing attention for application to visible light photocatalytic hydrogen evolution from water splitting due to their unique band structure and high physicochemical stability. In this study, g-C3N4-SiC heterojunction with loaded noble metal was constructed. The g-C3N4-SiC-Pt composite photocatalysts were successfully prepared by the combination method of a bio-reduction, sol-deposition and calcination. The layers of g-C3N4 were thinned and the SiC and Pt nanoparticles simultaneously were tightly bound to g-C3N4 by calcination in the process of preparing the g-C3N4-SiC-Pt. The heterojunction formed in the interface of SiC and g-C3N4 enhances the separation efficiency of the photogenerated electron-hole pairs. These composite photocatalysts achieve a high hydrogen evolution rate of 595.3 μmol·h-1·g-1 with a 1wt% of deposited Pt, 3.7- and 2.07-fold higher than g-C3N4-bulk and g-C3N4-SiC under visible-light irradiation with a quantum efficiency of 2.76% at 420 nm, respectively.
关键词： visible light,g-C3N4-SiC-Pt photocatalysts,hydrogen evolution,photocatalysis
更新于2025-11-21 11:01:37
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Effect of conduction band potential on cocatalyst-free plasmonic H <sub/>2</sub> evolution over Au loaded on Sr <sup>2+</sup> -doped CeO <sub/>2</sub>
摘要： There is little information on the effect of the conduction band (CB) position on plasmonic hydrogen (H2) formation under visible light irradiation over gold (Au) nanoparticles supported on semiconductors because there were no appropriate materials for which the CB position gradually changes. In this study, we analyzed the flatband potential of strontium ion (Sr2+)-doped cerium(IV) oxide (CeO2:Sr) and found that the CB position gradually shifted negatively from +0.031 V to ?1.49 V vs. NHE with an increase in the Sr2+ mole fraction. Plasmonic photocatalysts consisting of Au nanoparticles, CeO2:Sr and a platinum (Pt) cocatalyst were prepared and characterized by using X-ray diffraction, UV-vis spectroscopy, and transmission electron spectroscopy. Photocatalytic reaction under visible light irradiation revealed that H2 was produced over Au nanoparticles supported on CeO2:Sr having the CB potential of ?0.61 V vs. NHE and that the negative limit of the CB position for electron injection from Au nanoparticles existed between ?0.61 V and ?1.49 V vs. NHE. We found that Au/CeO2:Sr plasmonic photocatalysts also produced H2 without the aid of a Pt cocatalyst due to the sufficiently negative potential of electrons injected into the CB of CeO2:Sr.
关键词： hydrogen evolution,visible light irradiation,gold nanoparticles,plasmonic photocatalysts,strontium-doped cerium oxide
更新于2025-11-19 16:51:07
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Preparation of Ag-doped Bi5O7I composites with enhanced visible-light-induced photocatalytic performance
摘要： A novel heterostructure photocatalysts, Ag-doped Bi5O7I composites (Ag/Bi5O7I), were synthesized by a simple hydrothermal method. Compared with Bi5O7I, Ag/Bi5O7I composites had a stronger light absorption in the visible and near-infrared region and the light absorption edge of Ag/Bi5O7I composites had a slight red shift. Moreover, Ag/Bi5O7I composites possessed a higher photocatalytic activity than Bi5O7I on the degradation of rhodamine B (RhB) and methyl orange (MO) under visible-light irradiation (λ ≥ 420 nm). When the content of Ag was 1%, the degradation efficiency of the Ag/Bi5O7I composites toward RhB and MO reached the maximum value, which was about 20.2 and 7.6 times higher than that of Bi5O7I, respectively. The trapping experiments shown that superoxide radicals and holes were the main active species in the photodegradation process. The excellent photocatalytic performance could be attributed to Ag/Bi5O7I heterojunction and surface plasma resonance effect of Ag, which could increase absorption of visible light and cause the efficient separation and migration of carriers.
关键词： Ag-doped Bi5O7I,Visible-light,Surface plasma resonance,Heterostructure photocatalysts
更新于2025-11-14 17:03:37
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Structural and photocatalytic properties of co-doped hybrid ZrO2–TiO2 photocatalysts
摘要： In this study, pure TiO2, ZrO2, and hybrid ZrO2–TiO2 photocatalysts were synthesized through solgel process and calcined at three different temperatures. The synthesized photocatalysts were characterized using powder X-ray diffraction (PXRD), field-emission scanning electron microscopy (FESEM), Brunauer–Emmet–Teller (BET), ultraviolet–visible (UV–Vis) spectrometer, and photoluminescence (PL) spectrometer. The PXRD patterns show that the rutile phase of TiO2 was suppressed through co-doping with ZrO2 and produced small crystallite size. The hybrid photocatalysts with small crystallite size recorded the highest surface area of 114.7 m2/g compared to pure TiO2 and ZrO2 photocatalysts as confirmed by BET analysis. Irregular size and shape was observed in the hybrid photocatalysts compared to spherical shape and size in TiO2 and flaky shape in ZrO2 as shown by the FESEM images. The optical properties of the photocatalysts investigated using UV–Vis spectroscopy showed a decrease in band gap energy of pure TiO2 through linear extrapolation from the Tauc’s plot despite the slightly higher band gap energy of the hybrid photocatalysts. However, PL analysis showed that doping of ZrO2 into TiO2 increased the separation efficiency of the electron–hole pairs and enhanced the photocatalytic activity. The phenol degradation of the hybrid ZrO2–TiO2 photocatalysts was higher compared to those of the pure TiO2 and ZrO2.
关键词： Hybrid TiO2–ZrO2 photocatalysts,Solgel,Phenol degradation
更新于2025-11-14 15:25:21
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A Full-Spectrum Metal-Free Porphyrin Supramolecular Photocatalyst for Dual Functions of Highly Efficient Hydrogen and Oxygen Evolution
摘要： A full-spectrum (300–700 nm) responsive porphyrin supramolecular photocatalyst with a theoretical solar spectrum efficiency of 44.4% is successfully constructed. For the first time, hydrogen and oxygen evolution (40.8 and 36.1 μmol g?1 h?1) is demonstrated by a porphyrin photocatalyst without the addition of any cocatalysts. The strong oxidizing performance also presents an efficient photodegradation activity that is more than ten times higher than that of g-C3N4 for the photodegradation of phenol. The high photocatalytic reduction and oxidation activity arises from a strong built-in electric field due to molecular dipoles of electron-trapping groups and the nanocrystalline structure of the supramolecular photocatalyst. The appropriate band structure of the supramolecular photocatalyst adjusted via the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of the porphyrin gives rise to thermodynamic driving potential for H2 and O2 evolution under visible light irradiation. Controlling the energy band structure of photocatalysts via the ordered assembly of structure-designed organic molecules could provide a novel approach for the design of organic photocatalysts in energy and environmental applications.
关键词： supramolecular photocatalysts,photocatalysis,full spectrum,dual functions,dipoles
更新于2025-09-23 15:23:52
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Radiative and non radiative recombinations study in the novel nanocomposites BiVO4/3DOM-TiO2, ZnO/3DOM-TiO2 and BiVO4/3DOM-ZnO: Application to the photocatalysis
摘要： A theoretical investigation of optical proprieties of three nanostructures such as BiOV4/3DOM TiO2, ZnO/3DOM TiO2 and BiOV4/3DOM ZnO has been presented and discussed. The study based on a one band effective mass approximation model was developed to calculate the charge carrier energies on various parameters of nanostructures including their size. We computed the optical properties for both spherical BiVO4 and ZnO nanoparticles incorporated in the three dimensionally ordered macroporous inverse opal TiO2 nanocomposites (3DOM-TiO2 ). At first and by solving a three dimension Schr?dinger equation we calculated the dependence of charge carriers energies on the size of nanoparticles. Then we investigated the variation of the excitonic energy of BiOV4/3DOM-TiO2, ZnO/3DOM-TiO2 and BiOV4/3DOM-ZnO as function of the radius of these nanostructures into taken account the effects of dielectric and coulomb interaction between charge carriers. We showed that the radiative recombination lifetime is enhanced with decreasing BiVO4 and ZnO quantum dots (QDs) size. It was found that as the size of the dot is reduced the confinement of charge carriers and the optical gap are increased. The optical gap of the ZnO/3DOM-TiO2 is larger than both BiOV4/3DOM-TiO2 and BiOV4/3DOM-ZnO especially for small radius. It was also found that radiative life time in the BiOV4/3DOM-TiO2, ZnO/3DOM-TiO2 and BiOV4/3DOM-ZnO increased by increasing the radius of these nanostructures. In addition, we have also showed that, the radiative lifetime in the ZnO/3DOM-TiO2 nanostructure is less than both BiOV4/3DOM-TiO2 and BiOV4/3DOM-ZnO nanostructures. Finally, we have studied and discussed the Auger process in BiOV4/3DOM-TiO2, ZnO/3DOM-TiO2 and BiOV4/3DOM-ZnO nanostructures. At first, we have showed that the auger process is important when the radiuses of nanostructures are less than 2nm. Then we have also showed that this process is more important for ZnO/3DOM-TiO2 compared to the other nanostructures.
关键词： Photocatalysts,radiative lifetime,Auger recombination lifetime,nanocomposites
更新于2025-09-23 15:23:52
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Solar Heterogeneous Photocatalytic Oxidation for Water and Wastewater Treatment: Problems and Challenges
摘要： Solar operation of heterogeneous photocatalytic oxidation reactors is looked at as a sustainable process for water and wastewater treatment, because it does not consume electric power and chemicals. However, there are still problems for technical-scale application. The problems addressed in this article are large area demand, water evaporation from open reactors and lack of simple photocatalyst recovery. An optimum solar reactor type is the parabolic compound collector reactor with borosilicate glass tubes. Challenges for further research are improvement in mass transfer as well as identification of novel photocatalysts which make use also of visible light, are efficient and stable, and are easy to be produced in an economically feasible way. Also the combination of photocatalysts with adsorbents is promising. Although membrane filtration processes have been successfully combined with solar photocatalytic oxidation and represent a safe barrier against spreading photocatalyst nanoparticles into the aquatic environment, more simple and less energy-consuming methods for photocatalyst recovery would be desirable.
关键词： Photocatalyst recovery,Novel photocatalysts,Solar photocatalytic oxidation,Photocatalysis adsorption hybrid process,Mass transfer
更新于2025-09-23 15:23:52
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Dispute in photocatalytic and photoluminescence behavior in ZnO/graphene oxide core-shell nanoparticles
摘要： ZnO/graphene oxide core-shell nanoparticles (ZGNPs) were prepared by via in-situ chemical synthesis and electrolysis. This report addresses the disagreement in the photocatalytic and photoluminescence behavior in this system. XRD, Raman, HRTEM, PL and UV-Vis were able to confirm ZnO nanoparticles and core-shell structures formation at various temperatures. A little shift was observed in Raman for ZGNPs after conjugating. PL showed a few peaks that were not related to the graphene, which depends on the synthesis route and defects. After conjugating between ZnO and Graphene, two mechanisms are suggested. The first is band structure modification in the boundary of core and shell. The second one is diffusion of functional group in GO as a dopant on ZnO surface.
关键词： Nanoparticles,Photoluminescence,Photocatalysts,Core-Shell,Nanocomposites,ZnO-Graphene
更新于2025-09-23 15:23:52
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Facile strategy for controllable synthesis of hierarchical hollow MoS2 microspheres with enhanced photocatalytic properties
摘要： Tailored design of photocatalysts with complicated hollow structures is of great importance for promoting environmental remediation. In this paper, monodispersed hierarchical hollow MoS2 microspheres have been prepared via a facile and economical hydrothermal method with the assistance of surfactant (polyethylene-polypropylene glycol (F68)). The unusual design displays three important features: large specific surface area, strong light absorption, and rich catalytic active sites. The specific surface area of the hierarchical hollow MoS2 microspheres is 21.75 m2g-1, which is higher than that of MoS2 particles (4.05 m2g-1) and commercial MoS2 (2.84 m2g-1). Meanwhile, the hierarchical hollow MoS2 microspheres possess strong light absorption around a broadband wavelength from 200 nm to 800 nm. Furthermore, the ordered MoS2 nanosheets which assemble to the outer surface of the hierarchical hollow MoS2 microspheres display rich catalytic active sites, which are beneficial in promoting the fast transport of charge carriers during the process of photocatalytic reaction. As a result, the photodegradation activity test demonstrates that the hierarchical hollow MoS2 microspheres exhibit excellent photocatalytic activity and recycling stability. The reaction rate constant of the hierarchical hollow MoS2 microspheres for the photodegradation of RhB is 25.32 and 18.18 times faster than that of MoS2 particles and commercial MoS2, respectively.
关键词： Unusual design,Photocatalysts,MoS2,Rich catalytic sites,Large surface area,Broadband absorption
更新于2025-09-23 15:23:52
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Enhancing the photocatalytic activity of ZnO by using tourmaline
摘要： The ZnO/tourmaline composite was synthesized by a facile precipitation-hydrothermal method. The composite showed significantly enhanced photocatalytic activity towards degradation of methylene blue (MB) compared with pure ZnO. The degradation rate maintained 90.8% after five successive photocatalytic reaction cycles in the presence of the composite. The results indicated that the enhanced photocatalytic performance of the composite was ascribed to the exposed active sites originated from the improved specific surface area, good interaction between ZnO and tourmaline, and furthermore, tourmaline’s ability of leading the photo-induced e- transferred directionally to achieve separation of e-/h+ pairs. As an earth-abundant polar mineral, tourmaline had potential application in the photocatalytic field.
关键词： Semiconductors,Photocatalysts,Composite materials,Tourmaline,ZnO
更新于2025-09-23 15:23:52