Changsha University

About: Changsha University is a education organization based out in Changsha, China. It is known for research contribution in the topics: Photocatalysis & Adsorption. The organization has 1820 authors who have published 1695 publications receiving 18985 citations.

Enhanced photocatalytic activity of g-C3N4 for selective CO2 reduction to CH3OH via facile coupling of ZnO: a direct Z-scheme mechanism

Abstract: Photocatalytic CO2 reduction into renewable hydrocarbon solar fuels is considered as a promising strategy to simultaneously address the global energy and environmental issues. In this study, a binary g-C3N4/ZnO photocatalytic system was constructed via a one-step facile calcination method and further used as a photocatalyst for CO2 reduction. It was shown that the as-prepared g-C3N4/ZnO photocatalytic system exhibited enhanced photocatalytic activity for CO2 reduction by a factor of 2.3 compared with pure g-C3N4, while maintaining the original selectivity of pure g-C3N4 to convert CO2 directly into CH3OH. For the first time, the coupling effect of ZnO responsible for the improved photoactivity of g-C3N4 was fully illustrated and a direct Z-scheme mechanism rather than the conventional heterojunction-type mechanism was proposed to explain the better performances of the g-C3N4/ZnO binary composite photocatalytic system. The enhancement of photocatalytic CO2 reduction activity is attributed to the highly efficient ZnO-to-g-C3N4 electron transfer occurring at the intimate contact interface between the g-C3N4 phase and ZnO phase. This work will provide new deep insights into the rational construction of a g-C3N4-based photocatalytic system and the design of a direct Z-scheme system without an electron mediator for photocatalytic CO2 reduction reactions.

Enhanced photocatalytic activity and stability of Z-scheme Ag2CrO4-GO composite photocatalysts for organic pollutant degradation

Abstract: Silver chromate-graphene oxide (Ag2CrO4-GO) composites are prepared by a facile precipitation method. The resulting Ag2CrO4-GO composites exhibit excellent photocatalytic activity and stability towards the degradation of the dyes and phenol in aqueous solution under visible-light irradiation. The optimal composite with 1.0 wt% GO content shows the highest photocatalytic activity for methylene blue (MB) degradation, which is 3.5 times that of pure Ag2CrO4 particles. The enhanced photocatalytic activity is mainly attributed to the formation of Ag2CrO4-GO Z-scheme heterojunction that can not only facilitate the separation and transfer of the photogenerated charge carriers, but also preserve a strong oxidation and reduction ability. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Ag2CrO4 by transferring the photogenerated electrons of Ag2CrO4 to GO. The present work provides a new understanding into design and fabrication of the GO/silver compound composite photocatalysts.

Ag2CrO4/g-C3N4/graphene oxide ternary nanocomposite Z-scheme photocatalyst with enhanced CO2 reduction activity

Abstract: Graphitic carbon nitride (g-C3N4)-based photocatalysts holds great promise on photocatalytic CO2 conversion into solar fules; however, the efficiency of pristine g-C3N4 is currently limited by its poor visible light absorption and rapid charge recombination. Employing silver chromate (Ag2CrO4) nanoparticles as photosensitizer and graphene oxide (GO) as cocatalyst, a novel ternary Ag2CrO4/g-C3N4/GO composite photocatalyst was fabricated for photocatalytic CO2 reduction into methanol (CH3OH) and methane (CH4). The ternary composites exhibited an enhanced CO2 conversion activity with a turnover frequency of 0.30 h–1, which was 2.3 times that of pristine g-C3N4 under simulated sunlight irradiation. The enhanced photocatalytic activity was due to broadened light absorption, higher CO2 adsorption and more efficient charge separation. Specifically, due to the matched band structure and appropriate loading ratio of Ag2CrO4, a direct Z-scheme Ag2CrO4/g-C3N4 heterojunction is formed, driven by the internal electric field across the Ag2CrO4/g-C3N4 interface. The formation of the direct Z-scheme heterojunction is substantiated by radical scavenging experiments and density functional theory calculations, and it benefits the photocatalytic reaction by accelerating the charge separation and improving the redox ability. Furthermore, GO cocatalyst not only promotes the charge transfer but also provides plentiful CO2 adsorption and catalytic sites. This work exemplifies the facile development of ternary g-C3N4-based photocatalysts with high CO2-conversion activity by coupling a small amount of Ag-based photosensitizer and metal-free cocatalyst.

Review on nanoscale Bi-based photocatalysts

Abstract: Nanoscale Bi-based photocatalysts are promising candidates for visible-light-driven photocatalytic environmental remediation and energy conversion. However, the performance of bulk bismuthal semiconductors is unsatisfactory. Increasing efforts have been focused on enhancing the performance of this photocatalyst family. Many studies have reported on component adjustment, morphology control, heterojunction construction, and surface modification. Herein, recent topics in these fields, including doping, changing stoichiometry, solid solutions, ultrathin nanosheets, hierarchical and hollow architectures, conventional heterojunctions, direct Z-scheme junctions, and surface modification of conductive materials and semiconductors, are reviewed. The progress in the enhancement mechanism involving light absorption, band structure tailoring, and separation and utilization of excited carriers, is also introduced. The challenges and tendencies in the studies of nanoscale Bi-based photocatalysts are discussed and summarized.