| This study proposes a photo-electrode material technology that may significantly change the development of photo-electrochemical hydrogen production technology. With this study, it is expected that hydrogen production using photo-electrodes at a commercial level will be possible soon. |
Hydrogen is an eco-friendly energy source that reduces greenhouse gases and fine dust. It is essential for building a clean and safe society. Currently, hydrogen production relies on utilizing the by-product hydrogen from petrochemical processes and extracting from natural gas. However, these production methods generate CO2, creating an ironic situation of contributing to global warming while aiming for a clean Earth.
The commercialization of solar-based production technology is urgently needed to address this issue. The U.S. Department of Energy (DOE) set specific goals for expanding clean hydrogen production in the “US National Clean Hydrogen Strategy and Roadmap” released in June 2023. Also, it established targets for commercializing solar-based hydrogen production technology at the level of a solar-to-hydrogen (STH) conversion efficiency of over 10 %, stability for over 1000 hours, and a PEC (photo-electrochemical) H2 system cost of $ 2-4 per kilogram. Various research and investments are underway to achieve these goals.
Hydrogen (H2) production requires photo-electrodes with high PEC activity and durability. However, surface defects, photo-corrosion instability, and especially instability at high potentials degrade PEC performance and stability. In this study, we introduced an HfO2 protective layer and a NiPt single-atom catalyst to improve the surface of a BiVO4 photoelectrode, classified as a low-cost material, and controlled strong corrosivity, achieving a high stability of over 800 hours. This was evaluated under one-sun solar light (100 mW/cm²). This study has significant implications as it is the first demonstration of long-term performance in the world. Furthermore, we achieved a solar-to-hydrogen conversion efficiency of 6.0 % of the self-driven photo-electrochemical water splitting device based on the BiVO4 photoelectrode, which is significant as it is approximately 90 % of the theoretical efficiency of the BiVO4 material.
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