Rational Design of Branched WO₃ Nanorods Decorated with BiVO₄ Nanoparticles by All-Solution Processing for Efficient Photoelectrochemical Water Splitting

The formation of heterostructure between BiVO4 and WO3 is a promising strategy to design a high-performance photoanode. In this study, we prepared the highly crystalline branched WO3 nanorods decorated with BiVO4 nanoparticles by all-solution processes and achieved high photoelectrochemical (PEC) performances through the morphological design of WO3 bottom layer and BiVO4 decorations. WO3 nanorods with epitaxially grown nanobranches could be prepared via two-step hydrothermal method, and the BiVO4/WO3 heterostructure was formed by sequent electrodeposition of BiVO4 nanoparticles on branched WO3 nanorods. In comparison to bare WO3 nanorods counterpart, the macelike branched WO3 nanorods can present the enlarged surface area and improved light trapping properties from the morphological control of WO3 hierarchical nanostructures, endowing a 32.8% higher photocurrent around 0.85 mA/cm2 at 1.23 V vs reversible hydrogen electrode (RHE). While decorated with BiVO4 nanoparticles, the as-fabricated BiVO4/macelike WO3 nanorod heterostructure performs a much improved photocurrent of 3.87 mA/cm2 at 1.23 V vs RHE. Such a significant enhancement may result from the significantly enhanced light-harvesting and charge separation efficiency. This rational design of heterostructured photoanodes provides a facile, cost-effective, and scalable strategy to improve PEC performances.