Preparation,modification And Photoelectrochemical Performance Of ZnIn₂S₄ Photoanodes

Resource shortages and environmental pollution have become two major challenges to sustainable development of human society.Therefore,people are actively exploring and developing an ideal green energy to repleace fossil energy.As we all know,sunlight contains a lot of energy,and the photoelectrochemical(PEC)reaction driven by visible light is an effective way to solve the current energy and environmental crisis.Nano-ZnIn₂S₄ has better light absorption performance and chemical stability,and it has been widely studied in photocatalysis field,but development and application of the powder photocatalyst has been hindered by its non-recyclable.The synthesis of ZnIn₂S₄ nanosheet array(NSAs)electrodes by hydrothermal method can solve the above problems well.At the same time,the ZnIn₂S₄ NSAs electrode has many shortcomings,such as a narrow visible light response range,low photo-generated carrier separation efficiency,and insufficient photo-generated hole-electron redox ability.Based on these,the studies in this thesis mainly focus on the ZnIn₂S₄ NSAs electrode.This thesis constructs an efficient visible light absorption system by supporting different promoters and introducing crystal defects to improve the PEC performance of ZnIn₂S₄ NSAs electrode,and the relevant contents are listed as following:(1)ZnIn₂S₄ NSAs were synthesized on the FTO conductive substrate by hydrothermal method,and then ZnIn₂S₄/Au NSAs electrode was constructed by light deposition.The results showed that the highest photocurrent density of ZnIn₂S₄/Au NSAs electrode reached 0.27 m A cm^-2,and the PEC N₂ fixation activity increased from 1.09?g cm^-2 h^-1 to 2.26?g cm^-2 h^-1.The main reason for the improved performance of ZnIn₂S₄/Au NSAs electrode is that Au nanoparticles can produce localized surface plasmon resonance(LSPR),which stimulates ZnIn₂S₄ to generate more photo-generated carriers.(2)In order to further improve the efficiency of photogenerated carrier separation and utilization,firstly,an appropriate amount of Au nanoparticles were deposited on the FTO substrate by electrodeposition method,and then FeOOH/ZnIn₂S₄/Au electrode was synthesized by hydrothermal and chemical bath deposition route.FeOOH and Au promote the directional migration of holes and electrons,respectively,and promote the spatial separation of photogenerated carriers.The LSPR effect of Au promotes the visible light response range of the photoelectrodes,and further improves the high PEC performance.(3)Hydrothermal method was used to synthesize ZnIn₂S₄ NSAs on the FTO conductive substrate,and a large number of sulfur vacancies were introduceed on the surface of ZnIn₂S₄ nanosheets using a unique plasma cleaning technology.PEC tests showed that the photocurrent density of 60W/ZnIn₂S₄ NSAs under 1.23 V_RHE bias voltage reached 0.3 m A cm^-2,the total hydrogen production reached 6.86?mol cm^-2within 2.5 hours,which was more than twice of 0W/ZnIn₂S₄ NSAs.The results showed that the sulfur vacancies in the ZnIn₂S₄ NSAs electrodes as defects can capture a large number of photogenerated electrons,thereby reducing the recombination of photogenerated electrons and holes,extending the lifetime of photogenerated carriers,and improving PEC performance of ZnIn₂S₄ NSAs electrodes.This paper has 39 pictures,6 tables,and 133 references.