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

• Published in: Carbon energy 2023-06, Vol.5 (6), p.n/a
• Main Authors: Lee, Mi Gyoung, Yang, Jin Wook, Park, Ik Jae, Lee, Tae Hyung, Park, Hoonkee, Cheon, Woo Seok, Lee, Sol A., Lee, Hyungsoo, Ji, Su Geun, Suh, Jun Min, Moon, Jooho, Kim, Jin Young, Jang, Ho Won
• Format: Article
• Language: English
• Subjects: Bismuth oxides; bismuth vanadate; Carbon; Catalysts; Diffusion barriers; Diffusion layers; Diffusion length; Efficiency; Electrodes; Electron transport; Glass substrates; heterojunction; Heterostructures; Hydrogen; Indium; indium oxide; Indium oxides; Microscopy; Nanorods; Nanostructure; Nickel; Nitrates; Oxidation; Perovskites; Photoelectric effect; photoelectrochemical water splitting; Photovoltaic cells; Reaction kinetics; Solar cells; Spectrum analysis; Splitting; Sulfite; Thin films; Vanadate; Vanadates; Water splitting
• ISSN: 2637-9368; 2637-9368
• DOI: 10.1002/cey2.321

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. The introduction of In2O3 nanorods (NRs) as an electron transport layer created a type Ⅱ heterojunction with bismuth vanadate (BiVO4) nanodots, enabling a near‐complete charge separation at 1.23 VRHE. The tannin–nickel–iron complex (TANF) as an oxygen evolution catalyst expedites the water oxidation kinetics of a BiVO4/indium oxide (In2O3) NR photoanode. Finally, the photovoltaic–photoelectrochemical tandem cell comprising the TANF/BiVO4/In2O3 NR photoanode and the perovskite/Si solar cell shows a solar‐to‐hydrogenconversion efficiency of 6.2% for unbiased solar water splitting.