Manganese(ii) phosphate nanosheet assembly with native out-of-plane Mn centres for electrocatalytic water oxidation.

Nature selects Mn-clusters as catalysts for water oxidation, which is a significant reaction in photosynthesis. Thus, it is of critical importance to develop Mn-based superstructures and study their catalytic details for water-splitting-based renewable energy research. Herein, we report a manganese(ii) phosphate nanosheet assembly with asymmetric out-of-plane Mn centers from the transformation of amine-intercalated nanoplates for efficient electrocatalytic water oxidation in neutral aqueous solutions. From structural and computational studies, it is found that the native out-of-plane Mn centers with terminal water ligands are accessible and preferential oxidation sites to form active intermediates for water oxidation. In addition, the asymmetry can stabilize the key Mn intermediate, as demonstrated by electrochemical and spectrometric studies. This study delivers a convenient strategy to prepare unique nanosheet assemblies for electrocatalysis and fundamental understandings of oxygen evolution chemistry.