LAUSR

Abstract BiVO4 is one of the most promising photoanodes for photoelectrochemical (PEC) water splitting. However, BiVO4 is limited by less-than-unity efficiencies of light absorption and charge separation due to a trade-off between the long penetration depth of photons and relatively short length carrier diffusion. Here, an antenna/spacer/reflector based Au/BiVO4/WO3/Au nanopatterned photoanode is designed by integrating ultrathin BiVO4 layer between two kinds of Au nanospheres (NSs) with different sizes. The large underlying nanopatterned Au NSs sever as current collector and back reflector to reflect the incident light by Bragg reflection of the highly ordered Au NSs array, while the small surface Au NSs act as antennas to absorb the incident and reflected light, which concentrates the light energy to the BiVO4 layer. Moreover, a strong electromagnetic field is created in the BiVO4 spacer due to the coupling interaction between the reflector and antenna, which promotes the charge separation of BiVO4. Based on this unique antenna/spacer/reflector structure, the ultrathin BiVO4 of only 70 nm achieves a photocurrent density of 1.31 mA/cm2 at 1.23 VRHE, which demonstrates an impressive 3.23 fold enhancement by the combined plasmonic effects, and it further increases to 1.97 mA/cm2 after depositing FeOOH catalyst. The strategy paves a way for other semiconductors and thin-film optoelectronic devices to improve their performance.