Boosting photoelectrochemical water splitting: enhanced hole transport in BiVO4 photoanodes via interfacial coupling†

Abstract

In the realm of photoelectrochemical (PEC) water splitting, the oxygen evolution reaction (OER) poses a significant efficiency bottleneck. To address this challenge, multi-interfacial optimization of BiVO₄-based composites to enhance charge transport within the material matrix has emerged as a pivotal strategy for improving PEC performance. In this study, we present a comprehensive report on the design and fabrication of an innovative heterostructured NiFe-LDH/Co₃O₄/BiVO₄ thin film. Through a series of meticulously designed experiments and characterization techniques, we delve into the operational mechanisms underlying the interfacial coupling effect of this composite photoanode. Notably, the sandwich-configured NiFe-LDH/Co₃O₄/BiVO₄ photoanode demonstrates remarkable OER performance. Under standard solar simulation conditions, it achieves a photocurrent density of 4.7 mA cm⁻² at 1.23 V vs. RHE in a 1.0 M KBi solution, marking a nearly fourfold enhancement compared to the pure BiVO₄ photoanode. Our structural, compositional, and electrochemical analyses reveal that NiFe-LDH functions as a highly effective cocatalyst, substantially reducing the overpotential for water oxidation. Furthermore, the strategic incorporation of Co₃O₄ not only establishes a built-in electric field at the BiVO₄ interface, thereby facilitating efficient charge separation, but also fine-tunes the electronic structure of the metal centres in NiFe-LDH, leading to an increased number of oxidation active sites. These synergistic effects significantly enhance the charge separation efficiency and long-term operational stability of the PEC system. These advancements are attributed to the intricate interfacial coupling between NiFe-LDH, Co₃O₄ nanoparticles, and BiVO₄, underscoring the immense potential of this composite material in the domain of efficient photoelectrocatalysis.