Distinct Promotion of PEC Water Oxidation of Ta₂O₅/α-Fe₂O₃/Co-Ni PBA via Coupling Ni 3d with O 2p

The development of robust and effective photoanodes is crucial for photoelectrochemical hydrogen production via total water splitting. Herein, the Ta₂O₅/α-Fe₂O₃/Co-Ni PBA (TFPB-1) photoanode was constructed by the compositing n-type Ta₂O₅ and n-type α-Fe₂O₃ followed by the deposition of p-type Co-Ni PBA. The IPCE of TFPB-1 was increased to 35.4% compared to 13.9% for Ta₂O₅ owing to the significantly improved light absorption efficiency, carrier separation efficiency and injection efficiency. The TFPB-1 achieved a current density of 2.78 mA cm^-2 at 1.23 V (vs RHE), which was around 18.5 times that of Ta₂O₅. The OER overpotential over TFPB-1 was reduced to 0.59 V compared to 1.13 V for Ta₂O₅, resulting in a substantial reduction in the free energy of PEC water oxidation over TFPB-1. As a result, TFPB-1 exhibited remarkably enhanced photoelectrocatalytic activity for oxygen evolution through water oxidation.