Preparation And Properties Of The Silver-based Solid Solution Composite Materials

During the past decades,the rapid development of modern industry has caused serious environmental pollution which lead to devastating consequences on aquatic environment.Semiconductor photocatalysis applied in decomposing organic pollutants is considered as one of the most promising technologies because of it's high efficiency,eco-friendly character and low cost.In recent years,developing new visible-light response photocatalystic materials is research focus in photocatalystic field.Silver-based solid solution AgAl_1-xGa_xO₂ displays the capability of eliminating organic compounds considering the unique electronic and crystal structures.In addition,the bandgap together with the visible light absorption are easily tailored by controlling the elementary components due to the hybridization of atom orbits in the conduction band.Meanwhile,two-dimensional composites with abundant coupling interfaces is an effective approach to expand the light absorption range and enhance charge separation rate,which both greatly contribute to the photocatalytic performance.Therefore,coupling g-C₃N₄ and Bi₂WO₆ sheets with?-AgAl_1-xGa_xO₂ platelets can easily achieve the effective interfacial contact and promote the construction of layered heterostructure.The crystal phase,energy band structure,microstructure,absorption spectra and intrinsic relationship with photocatalytic activity of heterostructure are systematically studied.The possible photocatalyticprocess and mechanism related to the energy band of two phases are proposed for degrading organic pollutants under visible light irradiation.The specific research contents and conclusions are as follows:Herein,two-dimensional g-C₃N₄/?-AgAl_0.4Ga_0.6O₂ p-n heterostructure is for the first time synthesized by phase transition method under hydrothermal treatment.Based on the SEM and TEM results,the g-C₃N₄ and?-AgAl_0.4Ga_0.6O₂ with similar morphology closely contact each other forming p-n heterojunction.UV-vis absorption of the heterostructure is modulated efficiently by controlling the phase component,heterojunction sample can expand visible light absorption and also exhibit a red shift of the absorption edge.Photoelectrochemical properties indicates that x-CN/AO heterostructure has a more effective separation and migration of photo-generated electron-hole pairs,the recombination of charge carriers is greatly hindered,and the p-n heterostructure enhances the electron lifetime.When utilized as photocatalysts for MO degradation under visible light irradiation,the g-C₃N₄/?-AgAl_0.4Ga_0.6O₂ heterostructure exhibits a significantly enhanced photocatalysis activity in decomposing MO in comparison with pristine g-C₃N₄ and?-AgAl_0.4Ga_0.6O₂.In particular,the g-C₃N₄/?-AgAl_0.4Ga_0.6O₂ with a molar ratio of0.75 exhibits the most excellent photocatalytic performance with a rate constant of0.0227 min^-11 which is almost 5.5 times higher than the 0.0041 min^-11 of pure g-C₃N₄.Besides,the reaction kinetics and the photocatalytic mechanism related to the energy band are proposed for degrading organic pollutants.In this study,a novel lamellar composites?-AgAl_0.4Ga_0.6O₂/Bi₂WO₆ was successfully prepared via hydrothermal method.The X-ray diffraction and SEM results exhibited that the samples with high crystallinity and similar morphology of two phases facilitates the close and high density composites.The UV-Vis absorption spectra exhibits compared with Bi₂WO₆ and?-AgAl_0.4Ga_0.6O₂,BiW/AgAlGa composites displays a red shift in absorption edge and the absorption of visible light is enhanced meanwhile.Based on the photoelectrochemical results,the15%-BiW/AgAlGa p-n composites show improved carrier separation efficiency,photoluminescence results indicates that the recombination of the photogenerated electron-hole pairs is suppressed.This is attributed to the formation of in-built electric field across the interfaces due to their different semiconductive characteristics.In summary,the visible light photocatalytic performances of the semiconductors can be optimized through composition adjustment which could widen the absorption range and enhanced separation and transfer of the photoinduced carriers.This is of great significance to further improve the performance of photocatalytic materials and expand the current photocatalytic material system,and the research results have further deepened our understanding of the catalytic mechanism,promote the development of photocatalytic technology and the practical application in production and life.