Activating and stabilizing lattice oxygen by synergetic defect engineering and surface reconstruction into CeOx/CoP for electrocatalytic oxygen evolution

Abstract

Rare-earth (RE) elements have become important promoters in modulating transition metal electrocatalysis, but the understanding of the structural evolution and electrocatalytic mechanism remains limited. Herein, we demonstrate that surface reconstruction of CeO_x/CoP as a mode to understand the dynamic structure reconstruction process and the actual catalytic mechanism. In situ reconstruction of CeO_x/CoP precursor catalyst to form a highly active CeO_x-CoOOH phase for OER is presented, during which CeO_x accelerates the surface reconstruction and stabilizes the reconstructed CoOOH layer, and serves for dynamic oxygen buffer compensation and prevention of excessive loss of active species and lattice oxygen. Furthermore, the reconstructed surface on CeO_x-doped CoOOH triggers the lattice oxygen activation, as confirmed by experimental evidence from pH-dependent OER, tetramethylammonium cation adsorption and online electrochemical mass spectrometry measurements of ¹⁸O-labelled catalysts, thereby exhibiting excellent OER performance of 250 mV at 10 mA cm⁻² with satisfactory stability over 200 h. Theoretical analyses reveal that the unique 4f-2p-3d orbital coupling reinforces the Co-O covalency activating the LOM pathway. This work elucidates the concept of RE adjusting dynamic reconstruction for development of robust OER electrocatalysts, which may inspire the design of more efficient catalysts featuring activated lattice oxygen.