HfS2/GeSe Heterostructure Engineering for Superior Photocatalytic Hydrogen Generation: Design, Mechanism, and Efficiency

Abstract

This study constructs HfS2/GeSe heterostructures to address the issues of high carrier recombination and narrow light absorption in monolayer HfS2 for photocatalysis. DFT and AIMD calculations reveal stacking-I as the most stable structure, where electron transfer from HfS2 to GeSe forms a 2.86eV built-in electric field, enhancing photogenerated carrier separation. HER and OER occur in GeSe and HfS2 layers, respectively, enabling overall water splitting. The heterojunction shows a high hole mobility (5148.61 cm2V-1S-1 along the y-direction) and a theoretical STH efficiency of 24.63%. Gibbs free energy analysis indicates photogenerated carriers provide 0.39eV (HER) and 0.62eV (OER) overpotentials, requiring minimal external voltage at pH=0. This work theoretically demonstrates the HfS2/GeSe heterojunction’s potential for efficient photocatalysis, offering a new direction for clean energy material design.