Electrocatalytic water oxidation with manganese phosphates.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38360868.
- Also identified by DOI 10.1038/s41467-024-45705-1 and PMC identifier 10869713.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
As inspired by the Mn<sub>4</sub>CaO<sub>5</sub> oxygen evolution center in nature, Mn-based electrocatalysts have received overwhelming attention for water oxidation. However, the understanding of the detailed reaction mechanism has been a long-standing problem. Herein, homologous KMnPO<sub>4</sub> and KMnPO<sub>4</sub>•H<sub>2</sub>O with 4-coordinated and 6-coordinated Mn centers, respectively, are prepared. The two catalysts constitute an ideal platform to study the structure-performance correlation. The presence of Mn(III), Mn(IV), and Mn(V) intermediate species are identified during water oxidation. The Mn(V)=O species is demonstrated to be the substance for O-O bond formation. In KMnPO<sub>4</sub>•H<sub>2</sub>O, the Mn coordination structure did not change significantly during water oxidation. In KMnPO<sub>4</sub>, the Mn coordination structure changed from 4-coordinated [MnO<sub>4</sub>] to 5-coordinated [MnO<sub>5</sub>] motif, which displays a triangular biconical configuration. The structure flexibility of [MnO<sub>5</sub>] is thermodynamically favored in retaining Mn(III)-OH and generating Mn(V)=O. The Mn(V)=O species is at equilibrium with Mn(IV)=O, the concentration of which determines the intrinsic activity of water oxidation. This study provides a clear picture of water oxidation mechanism on Mn-based systems.