Dynamic variations of metal-O bonding in electro- and thermo-catalytic activation processes.

Abstract

Dynamically tracking the variations in electronic configurations and molecular binding of a catalyst under operando conditions remains a significant challenge. Herein, we report an in-situ millisecond-resolved wide-angle X-ray scattering technique to capture lattice distortion within a catalyst in low-temperature oxidation under electric- and thermal-induced catalysis and reveal the intrinsic mechanism of metal-O bonding on oxygen activation and the electro promotion. The c-directional lattice spacing of MnO₂ loaded on Ni foam is observed to undergo contraction and recovery processes with and without a direct electric field, respectively. Hard and soft X-ray absorption fine structure spectra, density functional theory and temperature-programmed reduction analyses confirm that an external current can effectively modulate the electronic configuration of manganese and oxygen atoms in the MnO₂ catalyst and alter the covalent bonding between Mn and O atoms by weakening the Mn-O bond, thereby enhancing the activity of lattice oxygen in the catalyst. This study provides scientific insights into the dynamic evolution of lattice distortion in externally field-induced catalytic reactions.