Controlled Synthesis And Performance Of Zinc And Bismuth Photocatalyst

In recent years,with the continuous development of semiconductor photocatalytic technology,the use of semiconductor materials to degrade organic pollutants in wastewater and produce hydrogen by decomposition of water is expected to become the effective way to solve the problem of environment and energy.In numerous semiconductor photocatalytic materials,zinc oxide?ZnO?and bismuth tungstate?Bi₂WO₆?become research emphasis due to the high activity,good stability and low cost.With a wider band gap,ZnO has a good response in ultraviolet light and exhibits low utilization rate for sunlight.However,despite this,modified ZnO is still has a high application value.At the same time,Bi₂WO₆ with a smaller band gap can effectively use of sunlight and shows excellent potential application.However,in the practically photocatalytic process,the photoinduced electrons and holes are easy recombination,which limits its potential applications in industry.To improve the photocatalytic activities of ZnO and Bi₂WO₆,morphological control and adjustable structures strategies were adapted and the main points in this paper are as follows:?1?ZnO with hierarchical microspheres were successfully synthesized by hydrothermal microemulsion route at 140? for 14 h using zinc acetate as raw materials,CTAB as a surfactant,and hexyl alcohol as a cosurfactant.Based on the observation of X-ray diffraction and scanning electron microscopy at the different reaction time periods,the formation mechanism of three-dimensional hierarchical ZnO microspheres was proposed.The photocatalytic activities of as-synthesized products were evaluated by monitoring the degradation of methylene blue solution.Due to the synergistic effects of the high crystallization and special hierarchical structure,the hierarchical ZnO microsphere exhibited thehighest photocatalytic activity.?2?Ag nanoparticles and g-C₃N₄ nanosheets modified Bi₂WO₆ microspheres were synthesized by hydrothermal method using L-lysine as a template agent.The impact of the different load of Ag and g-C₃N₄ on the photocatalytic activity were studied and the suitable load conditions were obtained.Compared with the pure Bi₂WO₆,Ag/g-C₃N₄/Bi₂WO₆ composites with the loading content of Ag of 0.5%and the g-C₃N₄ of 3% exhibited the highest degradation rate of rhodamine B dye,.The possible reason is that the synergistic effect Ag and g-C₃N₄ promoted the effective separation of photoinduced electrons and holes,therebyimproving the photocatalytic activity.?3?Bi₂WO₆/MoS₂ composite materials have been prepared via hydrothermal method.The electrochemical properties of the as-prepared samples were investigated by the transient photocurrent responses and linear sweep voltammetry?LSV?.Results showed when the loading content of Bi₂WO₆ was5 wt%,the Bi₂WO₆/MoS₂ composite exhibited a very low onset potential of-50 mV and a small Tafel slope of 96 mV per decade,indicating the excellent photocatalytic performance for hydrogen production.This result is mainly attributed to the chemical composition of materials and the transfer of photoelectron between the two semiconductors.