Fabrication and enhanced photoelectrochemical performance of WO3/ BiVO4 type-II heterojunction arrays

WO3/BiVO4 type-II heterostructured arrays (HAs) were fabricated on FTO glass substrate using a simple hydrothermal synthesis followed by a stepwise spin-coating (SSC) process. The particle size of BiVO4 and its distribution on the surface of WO3 nanorod arrays (NRAs) can be adjusted and optimized by SSC cycles. Compared to the bare WO3 nanorod array (NRA) photoelectrode, the WO3/BiVO4 photoelectrodes exhibit enhanced photoelectrochemical (PEC) properties. Among them, the WO3/BiVO4-4 photoelectrode exhibits the highest photocurrent density, which is approximately 3.6 times that of the bare WO3 NRA photoelectrode. The enhanced performance WO3/BiVO4-4 photoelectrode should be attributed to the introduction and reasonable distribution of BiVO4 nanoparticles (NPs) on the surface of WO3 NRAs, which not only leads to the formation of type II heterostructures, effectively suppresses electron-hole (e--h+) pairs recombination, promotes charge transfer and collection, but also greatly enhances light absorption and capture, increases the electrochemically active surface area, and reduces the initial potential and charge transfer resistance.