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 Ta 2 O 5 /α-Fe 2 O 3 /Co–Ni PBA (TFPB-1) photoanode was constructed by the compositing n-type Ta 2 O 5 and n-type α-Fe 2 O 3 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 Ta 2 O 5 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 Ta 2 O 5 . The OER overpotential over TFPB-1 was reduced to 0.59 V compared to 1.13 V for Ta 2 O 5, 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.