Realizing an efficient electron transfer process in the oxygen evolution reaction by modifying the electronic states around the Fermi level is crucial in developing high-performing and robust electrocatalysts1,2,3. Typically, electron transfer proceeds solely through either a metal redox chemistry (an adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (a lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level), without the concurrent occurrence of both metal and oxygen redox chemistries in the same electron transfer pathway1,2,3,4,5,6,7,8,9,10,11,12,13,14,15. Here we report an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger. In contrast to the traditional AEM and LOM, the proposed light-triggered coupled oxygen evolution mechanism requires the unit cell to undergo reversible geometric conversion between octahedron (NiO6) and square planar (NiO4) to achieve electronic states (around the Fermi level) with alternative metal and oxygen characters throughout the oxygen evolution process. Utilizing this electron transfer pathway can bypass the potential limiting steps, that is, oxygen–oxygen bonding in AEM and deprotonation in LOM1,2,3,4,5,8. As a result, the electrocatalysts that operate through this route show superior activity compared with previously reported electrocatalysts. Thus, it is expected that the proposed light-triggered coupled oxygen evolution mechanism adds a layer of understanding to the oxygen evolution research scene.
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The authors declare that all data supporting of the finding of this study are included within the paper and its Supplementary Information files and are available from the corresponding authors on request.
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We thank H. Wang and C. Wang for their help with figure design and A. Stefan for his advice on simulation. This work is financially supported by Singapore Ministry of Education (MOE) Tier 1 R284000226114 and MOE Tier 2 (MOE2018-T2-1-149), Agency for Science, Technology and Research (A*STAR) of Singapore. This research is also supported by A*STAR, grant number 152-70-00017, and computational resources were provided by National Supercomputing Centre Singapore (NSCC) and A*STAR Computational Resource Centre, Singapore (A*CRC). This project was partly supported by the Science and Engineering Research Council (SERC) of A*STAR of Singapore. This research is also supported by the Guangxi Bagui Scholar Foundation, Guilin Lijiang Scholar Foundation, Science and Technology Development Project of Guilin (20210216-1).
The authors declare no competing interests.
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Wang, X., Xi, S., Huang, P. et al. Pivotal role of reversible NiO6 geometric conversion in oxygen evolution. Nature 611, 702–708 (2022). https://doi.org/10.1038/s41586-022-05296-7