Revealing the synergistic role of the CoCu alloy and CN derived from a bimetallic MOF in promoting photoelectrocatalytic water oxidation

Abstract

The sluggish surface reaction kinetics, severe recombination of photoinduced carriers and poor stability of the photoanodes limit the practical application of photoelectrochemical (PEC) water decomposition. Herein, CoCu alloy nanoparticles, encapsulated tightly with a porous CN layer (CoCu/CN) via calcining CoCu-MOFs, were loaded onto Fe₂O₃ nanorods to construct Fe₂O₃@CoCu/CN photoanode catalysts that exhibited outstanding PEC water splitting capabilities, and a maximum photocurrent density of 3.12 mA cm⁻² at 1.23 V was achieved with an outstanding long-term durability. This performance is much better than that of the reported Fe₂O₃-based photoanodes. Based on experimental results and theoretical calculations, the synergistic roles of the CoCu alloy and CN carrier in promoting photoelectrocatalytic water oxidation are revealed. The strong interaction between components results in the redistribution of charge, which in turn provides a special hole transport channel and efficiently inhibits the recombination of photogenerated electrons and holes. The CoCu alloy nanoparticles lower the reaction's energy barrier, encourage the formation of reaction intermediates, and quicken the kinetics of the oxygen evolution reaction (OER). The C atoms in CoCu/CN that are close to the N atoms are the OER's active centres. All of these promote PEC water oxidation. This study reveals the influence of MOF-derived alloys and CN on the improvement of the photoelectrocatalytic water splitting performance, providing guidance for the rational design of efficient photoelectrocatalysis.