Rationally Constructing 2D Bi ₂ WO ₆ /BiVO ₄ Heterojunction Coated with a NiFe-Phosphate Cocatalyst for Enhanced Solar-Driven Water Splitting

Bismuth tungstate (Bi 2 WO 6 ) is considered one of the most promising candidate photoanodes for solar-driven photoelectrochemical (PEC) hydrogen production. However, the limited solar light absorption and rapid charge recombination restricted the practical PEC efficiency. Herein, a dual-modification method combining BiVO 4 coating and concurrent bimetallic Ni, Fe-based phosphate (NiFe-Pi) cocatalyst loading on two-dimensional (2D) Bi 2 WO 6 was rationally proposed to construct a ternary Bi 2 WO 6 /BiVO 4 /NiFe-Pi composite photoelectrode for increased solar-driven water-splitting activity. The formation of the Bi 2 WO 6 /BiVO 4 heterojunction improved solar photon absorption as well as accelerated charge transfer, and the NiFe-Pi cocatalyst further expedited water oxidation kinetics. As a result, the constructed Bi 2 WO 6 /BiVO 4 /NiFe-Pi hybrid photoelectrode achieved a photocurrent of about 89.4 μA·cm –2 at 1.23 V vs RHE, remarkably greater than that of the pristine Bi 2 WO 6 photoelectrode (about 1.0 μA·cm –2 ). In addition, a prominent enhancement in incident photon-to-current conversion efficiency was achieved for the synergistically modified photoelectrode. The enhancement in PEC activity is attributed to the synergistic effect of the heterojunction and cocatalyst, which contributed to improved solar photon utilization and promoted charge carrier transport. This study provides a novel and powerful strategy in designing and constructing Bi 2 WO 6 -based composite photoelectrodes to achieve elevated PEC performance.