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.