Component Design Of Cd_xZn_1-xS Based Catalysts For Solar H₂ Evolution Coupled With Degradation Of Plastic

Photocatalytic water splitting using sunlight for H₂evolution has been widely regarded as a promising solution to the global energy environmental concerns.However,the solar to H₂efficiency is not satisfying,partially due to the sluggish kinetics of the water oxidation reaction that limits the H₂evolution.To accelerate the reaction rate of photocatalytic H₂evolution,the half-reaction of photocatalytic water oxidation is usually replaced by the oxidation of expensive sacrificial agents（e.g.triethanolamine,methanol,lactic acid,etc.）.This way will undoubtedly increase the cost of photocatalytic H₂production.Therefore,motivated by economic reward,the photocatalytic water splitting for H₂production is moving to decouple the redox reactions of water to other ways.The coupling of photocatalytic H₂evolution and PET plastic degradation technology opened a new avenue for photocatalysis in both environment treatment and energy conversion.Cd_xZn_1-xS（0.2≤x≤0.8）solid solution,with controllable band gap and excellent photocatalytic performance in visible light region,was taken as the research object in this paper.We designed the structure and components of Cd_xZn_1-xS based catalysts and investigated their performance of photocatalytic H₂evolution coupled with the degradation of PET.（1）In order to study the effect of the energy band structure,the redox ability of the photo-generated holes,visible light absorption capacity,and carrier separation ability on the performance of photocatalytic H₂evolution coupled with the degradation of PET.We prepared 2D Cd_xZn_1-xS nanosheets with different molar ratio of Cd/Zn by cation exchange method and investigated their photocatalytic performance.The Cd_0.5Zn_0.5S exhibited the best H₂evolution rate under simulated sunlight due to the appropriate redox ability,great light absorption,and carrier separation abilities.Simultaneously,the PET was efficiently degraded to molecule compounds,such as formate,acetate,and so on.（2）In order to further promote the carrier separation ability,enhance light absorption and improve the performance of photocatalytic H₂evolution coupled with the degradation of PET.Based on the previous work,we introduced Mo S₂and fabricated 2D/2D Mo S₂/Cd_xZn_1-xS heterostructures by solvothermal method.The Mo S₂/Cd_0.5Zn_0.5S heterojunction with a loading mass of 4.3 wt%Mo S₂exhibited excellent H₂evolution rate of15.90 mmol·h^-1·g^-1,which can be ascribed to the excellent synergetic effects in terms of charge separation efficiency,light absorption capability,and suitable oxidation potential.Furthermore,the photocatalytic H₂evolution coupled with the degradation of the PET bottle is also demonstrated.This result is of great significance to solve PET plastic pollution on a large scale in the future.（3）In order to further improve the performance of photocatalytic H₂ evolution coupled with the degradation of PET in alkaline solution,we fabricated 2D/2D Co-Mo S₂/Cd_0.5Zn_0.5S heterostructure.It is found that Co-Mo S₂/Cd_0.5Zn_0.5S exhibited excellent performance of H₂evolution coupled with PET degradation,which can be ascribed to the incorporation of Co into Mo S₂could effectively lower the overpotential for H₂evolution in alkaline solution.In addition,the formation of strongly coupled interface between Co-Mo S₂nanosheets and Cd_0.5Zn_0.5S nanosheets could effectively promote the separation of photogenerated electrons and holes.