Activation of Semiconductor/Electrocatalyst/Electrolyte Interfaces Through Ligand Engineering for Boosting Photoelectrochemical Water Splitting

Abstract

The loading of transition-metal oxyhydroxide (TMOH) on semiconductor (SC) has been recognized as a promising approach for promoting photoelectrochemical (PEC) water splitting. Nonetheless, major challenges such as substantial carrier recombination and slow surface water oxidation continue to hinder the achievement of desirable PEC performance. This study proposes a feasible ligand engineering strategy to simultaneously boost charge separation and surface catalytic kinetics through coordinating 2-methylimidazole (2-MI) within a SC/TMOH system. In situ ultraviolet/visible spectroelectrochemistry (UV/vis-SEC) and density functional theory (DFT) calculations show that the coordination of the 2-MI ligand influences SC/TMOH and TMOH/electrolyte interfaces, notably enhancing the dynamics of hole transfer while simultaneously reducing the adsorption of oxygen-containing intermediates. As anticipated, the BiVO₄/FeNiOOH/2-MI photoanode demonstrates an impressive photocurrent of 6.52 mA cm⁻² at 1.23 V_RHE, featuring excellent photostability and a low onset potential of 0.35 V_RHE. Additionally, the 2-MI molecule can be employed in the development of alternative configurations, such as BiVO₄/FeNiOOH (soak)/2-MI, to improve PEC efficiency. This work opens a new horizon in designing of desirable photoanodes for efficient and stable PEC water splitting.