Metal–Organic Framework-Derived p-Cu₂O/n-Ce-Fe₂O₃ Heterojunction Nanorod Photoanode Coupling with a FeOOH Cocatalyst for High-Performance Photoelectrochemical Water Oxidation

Rapid charge recombination and slow water oxidation kinetics are key drawbacks that limit the photoelectrochemical water splitting efficiency of Fe2O3. In this work, we designed and fabricated for the first time that a metal–organic framework (MOF)-derived p-Cu2O/n-Ce-Fe2O3 nanorod array photoanode for the photogenerated charge effectively separated and transported at the Cu2O/Ce–Fe2O3 p–n heterojunction interface through a built-in electric field. In addition, the MOF-derived porous Cu2O nanoparticles have a large surface area, and thus, can offer more surface active sites for water oxidation. As anticipated, the novel structure Cu2O/Ce–Fe2O3 photoanode showed superior photocurrent density (3.2 mA cm–2), excellent bulk charge separation efficiency (38.4%), and surface charge separation efficiency (77.2%). After further modification with the FeOOH cocatalyst, the photocurrent density of the FeOOH/Cu2O/Ce–Fe2O3 photoanode reached 4.2 mA cm–2 at 1.23 VRHE (V vs reversible hydrogen electrode), having a low onset potential of 0.63 VRHE.