The BiVO 4 /WO 3 heterojunction is the ideal photoanode for highly efficient solar water splitting. Despite much effort, the low light absorption efficiency near the BiVO 4 band gap wavelength is still a major cause of loss of water-splitting efficiency. To address this issue, we introduce a BiVO 4 /WO 3 photoanode in which BiVO 4 single crystal nanoparticles (NPs) are decorated. In particular, we present a limited growth method in confined geometry to synthesize BiVO 4 NPs. These BiVO 4 NPs enhance Rayleigh-type light scattering, especially at the absorption edge wavelengths, resulting in increased light absorption efficiency (η abs ) at the corresponding wavelengths; the BiVO 4 NPs dramatically improved the η abs up to 60% at 500 nm, which is more than twice as high as the η abs values obtained for previously reported BiVO 4 photoanodes. In addition, BiVO 4 NPs exhibit high charge separation efficiency, especially at low bias potentials. This result indicates effective charge transport in the NP morphology. As a result, the BiVO 4 NP-coated WO 3 photoanode achieves a remarkably high water splitting photocurrent of 5.8 ± 0.18 mA cm -2 . This is the highest water-splitting photocurrent among those previously reported for BiVO 4 -based photoanodes.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (2011-0030253, 2016M3D3A1A01913254, and 2016R1D1A1B03935166). The Korea Basic Science Institute is also acknowledged for the SEM and EDS measurements.
© 2019 The Royal Society of Chemistry.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)