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

While bismuth vanadate (BiVO) 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 BiVO 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 BiVO porous nanotubes (BiVWO) was prepared for photoelectrochemical (PEC) water oxidation. One-dimensional, free-standing and porousBiVWO/Co-B nanotubes was synthesized through electrospun and electrodeposition process. BiVWO/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. BiVWO/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 BiVWO/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 BiVWO arrays. This work offers a simple preparation strategy for the integrated Co-B nanoparticle with BiVWO nanotube, demonstrating the synergistic effect of co-catalysts for PEC water oxidation.