Tailored BiVO ₄ /In ₂ O ₃ 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 (In 2 O 3 ) nanorods (NRs) as a novel electron transport layer for bismuth vanadate (BiVO 4 ) with a short charge diffusion length. In 2 O 3 NRs reinforce the electron transport and hole blocking of BiVO 4 , surpassing the state‐of‐the‐art photoelectrochemical performances of BiVO 4 ‐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/BiVO 4 /In 2 O 3 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/BiVO 4 /In 2 O 3 NRs from the tailored nanostructure and band structure for charge dynamics.