In-situ transcribed local coordinations from CoP nanorods pre-catalyst for efficient electrocatalytic oxygen evolution

Abstract

Transition metal-based compounds generally undergo dynamic surface changes to form active metal (oxy)hydroxides during the oxygen evolution reaction (OER). However, due to the core-shell structure formed by insufficient surface reconstruction and the complexity of the dynamic evolution process, understanding the origin of the catalytic performance derived from the pre-catalyst itself is a great challenge. Herein, we first reveal that a transcriptional relationship of local coordination between the pre-catalyst and the in-situ generated active species by regulating the lattice strain during phosphating with the aid of the nonequilibrium diffusion Kirkendall effect. The combination of electrochemical, ex-situ X-ray absorption fine structure spectroscopy (XAFS) and in-situ synchrotron radiation Fourier transform infrared spectroscopy (SR-FTIR) characterizations uncover that the variation trend of the first shell Co–O bond length in the active species is inherited from the Co–P bond length in the pre-catalyst and the shortened optimal distance of the second shell dual-Co sites is strongly correlated with the inherent OER activity. Thereby, a relation mapping to modify the coordination structure of the active species via the lattice strain of the pre-catalysts is established. This work not only provides a strategy to regulate OER performance via the lattice strain, but also sheds light on the role of the structural and compositional evolution of catalysts in activity during electrocatalytic reactions.