Synthesis And Photocatalytic Hydrogen Production Performance Of Bean Sprout Biochar CdS,ZnIn₂S₄,ZnS Composites

Increasingly severe energy crisis and environmental pressure force people to eagerly search for renewable and clean energy.As an environmentally friendly clean energy,hydrogen energy is considered to be one of the best alternatives to fossil energy in the future.Photocatalytic technology has attracted wide attention since its birth and has begun to develop rapidly.At present,photocatalytic hydrogen evolution technology has become one of the most effective strategies to alleviate the increasing energy demand and environmental pressure of modern society.Sulfides are the most typical photocatalysts,however,the photocatalytic hydrogen evolution（PHE） rate of them are not satisfactory owing to their respective disadvantages.In previous studies,carbon-based materials have been proved to be a class of materials that can distinctly enhance the PHE efficiency of sulfides.However,the synthesis of carbon materials such as graphene is complex and expensive,it is not convenient to large-scale use.It has attracted widespread attention as a result of its ability to slow down the rate of photo-generated electron-hole recombination.In this context,biochar has gradually attracted attention due to its wide range of sources,simple synthesis,and green friendliness.In this paper,biochar was used to modify the three typical sulfides of CdS,ZnIn₂S₄,and ZnS and their photocatalytic hydrogen evolution performance has been investigated.Bean sprouts biochar was first prepared using bean sprouts as raw materials.It is the first time that a series of bean sprouts biochar supported CdS（CdS@BC）,bean sprouts biochar ZnIn₂S₄（ZIS@BC） and bean sprout biochar ZnS（ZnS@BC） composite material are prepared by exploring the ratio between biochar and sulfide via hydrothermal method.It is found that the sulfide can be excellently dispersed on the bean sprout biochar carrier,reducing the self-agglomeration of the sulfide through the characterization and analysis of the three types of bean sprout biochar sulfide composite materials,which is conducive to increase the photocatalytic reaction active site.The photocatalytic hydrogen production performance of composite materials was studied,and it was found that the introduction of BC significantly improved the photocatalytic hydrogen production efficiency of CdS,ZnIn₂S₄,and ZnS.The photocatalytic hydrogen production efficiency of Cd S@BC-80,ZIS@BC-20 and ZnS@BC-30 are 17.7 mmol/g/h,5.0 mmol/g/h and 8.5 mmol/g/h,which is 3.93,2.50 and 4.25 times of pure CdS,ZnIn₂S₄ and ZnS respectively.Bean sprout biochar as a support can enhance the visible light response and accelerate the photoelectron-hole separation and transfer rate of the composite materials,which makes the photocatalytic performance of the composite material significantly improved.In addition,through cycle stability experiment,it is found that all the bean sprout biochar supported sulfide composites show good stability of photocatalytic hydrogen production.These results suggested that biochar derived from bean sprout could be a low-cost,renewable,environmentally friendly and metal-free cocatalyst for hydrogen generation.This article will serve as a useful guide for researchers who are currently concentrating on biochar-based composites for overcoming the photocatalytic-related challenges.