Tailored BiVO4/In2O3 nanostructures with boosted charge separation ability toward unassisted water splitting

Abstract

The development of new heterostructures with high photoactivity is a breakthrough for the limitation of solar-driven water splitting. Here, we first introduce indium oxide (In2O3) nanorods (NRs) as a novel electron transport layer for bismuth vanadate (BiVO4) with a short charge diffusion length. In2O3 NRs reinforce the electron transport and hole blocking of BiVO4, surpassing the state-of-the-art photoelectrochemical performances of BiVO4-based photoanodes. Also, a tannin–nickel–iron complex (TANF) is used as an oxygen evolution catalyst to speed up the reaction kinetics. The final TANF/BiVO4/In2O3 NR photoanode generates photocurrent densities of 7.1 mA cm−2 in sulfite oxidation and 4.2 mA cm−2 in water oxidation at 1.23 V versus the reversible hydrogen electrode. Furthermore, the “artificial leaf,” which is a tandem cell with a perovskite/silicon solar cell, shows a solar-to-hydrogen conversion efficiency of 6.2% for unbiased solar water splitting. We reveal significant advances in the photoactivity of TANF/BiVO4/In2O3 NRs from the tailored nanostructure and band structure for charge dynamics.