Modification Of CsPbBr₃ Perovskite Quantum Dot Photoanodes

As the industrialization process continues to deepen,the global reserves of fossil fuels are rapidly diminishing,which not only exacerbates the tension in energy supply but also leads to a series of environmental issues.Hydrogen energy,with its high calorific value of combustion and characteristic of not producing greenhouse gases during the combustion process,is widely recognized as playing a crucial role in the future energy structure.Photoelectrocatalytic（PEC）water splitting technology,which uses semiconductor photoelectrodes to decompose water into hydrogen and oxygen,not only achieves efficient conversion of light energy to chemical energy but also,through the combination with hydrogen storage technology,provides a new solution for achieving uninterrupted energy supply around the clock.However,the oxidation half-reaction in the PEC water splitting process is limited due to the slow kinetics of charge carriers,which severely restricts the practical application and promotion of PEC hydrogen production technology.Traditional metal oxide photoanodes suffer from low charge carrier mobility and short diffusion lengths,resulting in insufficient photoelectrocatalytic activity,which cannot meet the demand for high-efficiency hydrogen production.Therefore,the development of new photoanode materials with high charge carrier mobility and long diffusion lengths is of significant scientific research value and practical application prospects for improving the efficiency of photoelectrocatalytic water splitting and promoting the development of clean energy technology.All-inorganic perovskite CsPbBr₃ quantum dots（CsPbBr₃ QDs）are considered ideal photoanode materials due to their tunable bandgap,high visible light absorption coefficient,ultra-high single-junction theoretical open-circuit voltage,and suitable band position.However,the instability of the crystal structure of CsPbBr₃ QDs and the ionization binding of surface ligands severely hinder the effective transport of photogenerated charge carriers,affecting the photoelectrocatalytic activity.In response to this issue,this study focuses on improving the effective transport of photogenerated charge carriers in CsPbBr₃ QDs photoanodes and conducts in-depth research through the following strategies:（1）Enhancing crystal structure stability and accelerating charge carrier transport within quantum dots through partial substitution of Pb²⁺with Pd²⁺and Ru³⁺ions,which induce lattice contraction and adjust the tolerance factor and octahedral factor,thereby improving structural stability.Pd doping adjusts the valence band position,accelerating hole separation and transport,significantly enhancing the photocurrent density of photoanode.（2）Improving charge carrier transport on the quantum dot surface using guanidinium ions from guanidinium salts to bind with uncoordinated Pb²⁺,forming a guanidine carbonate（GA）matrix that mitigates agglomeration of CsPbBr₃ QDs,enhances light absorption,and effectively blocks surface defects to prevent charge carrier capture,further increasing photocurrent density.（3）Reducing the surface transfer resistance of quantum dots by substituting long-chain alkyl ligands with 1,2-Ethanedithiol（EDT）ligands,which shorten particle spacing and lower surface impedance.The cross-linking effect of thiol groups not only improves electron mobility but also passivates surface dangling bonds,enhancing charge separation and transport rates,and further increasing photocurrent density.（4）Enhancing charge carrier transport efficiency on the film surface by depositing quantum dots to passivate pinholes on perovskite thin film surfaces,increasing visible light absorption while suppressing ultraviolet light absorption.Utilizing surface ligand groups to passivate uncoordinated Pb²⁺and Br^-vacancy defects,effectively improving charge carrier transport efficiency.This study,through ion doping,surface ligand regulation,and the construction of a composite light absorption layer,achieves efficient separation and transport of photogenerated charge carriers within the semiconductor,on the surface,between adjacent particles,and on the film surface.This significantly enhances the photoelectrocatalytic activity of all-inorganic perovskite quantum dot photoanodes,providing important references for the development of halide perovskite photoanode materials.