Free-Standing Electrospun W-Doped BiVO4 Porous Nanotubes for the Efficient Photoelectrochemical Water Oxidation

While bismuth vanadate (BiVO₄) has emerged as a promising photoanode in solar water splitting, it still suffers from poor electron-hole separation and electron transport properties. Therefore, the development of BiVO₄ nanomaterials that enable performing high charge transfer rate at the interface and lowering charge recombination is urgent needed. Herein, cobalt borate (Co-B) nanoparticle arrays anchored on electrospun W-doped BiVO₄ porous nanotubes (BiV_0.97W_0.03O₄) was prepared for photoelectrochemical (PEC) water oxidation. One-dimensional, free-standing and porousBiV_0.97W_0.03O₄/Co-B nanotubes was synthesized through electrospun and electrodeposition process. BiV_0.97W_0.03O₄/Co-B arrays exhibit a unique self-supporting core-shell structure with rough porous surface, providing abundant conductive cofactor (W) and electrochemically active sites (Co) exposed to the electrolyte. When applied to PEC water oxidation. BiV_0.97W_0.03O₄/Co-B modified FTO electrode displays high incident photon-to-current conversion efficiency (IPCE) of 33% at 405 nm (at 1.23 V vs. RHE) and its photocurrent density is about 4 times to the pristine nanotube. The higher PEC water oxidation properties of BiV_0.97W_0.03O₄/Co-B porous nanotubes may be attributed to the effectively suppress the electron-hole recombination at electrolyte interface due to its self-supporting core-shell structure, the high electrocatalytic activity of Co and the good electrical conductivity of BiV_0.97W_0.03O₄ arrays. This work offers a simple preparation strategy for the integrated Co-B nanoparticle with BiV_0.97W_0.03O₄ nanotube, demonstrating the synergistic effect of co-catalysts for PEC water oxidation.