Molecularly Distorted Local Structure in Bi2CuO4 Oxide to Stabilize Lattice Oxygen for Efficient Formate Electrosynthesis

The electrochemical CO2 reduction reaction (CO2 RR) provides an economically feasible way for converting green energy into valuable chemical feedstocks and fuels. Great progress has been achieved in the understanding and synthesis of oxidized-based precatalysts; however, their dynamical changes of local structure under operando conditions still hinder their further applications. Here a molecularly distorted Bi2 CuO4 precatalyst for efficient CO2 -to-formate conversion is reported. X-ray absorption fine structure (XAFS) results and theoretical calculations suggest that the distorted structure with molecularly like [CuO4 ]6- unit rotation is more conducive to the structural stability of the sample. Operando XAFS and scanning transmission electron microscopy (STEM) results prove that quite a bit of lattice oxygen can remain in the distorted sample after CO2 RR. Electrochemical measurements of the distorted sample show an excellent activity and selectivity with a high formate partial current density of 194.6 mA cm-2 at an extremely low overpotential of -400 mV. Further in situ surface-enhanced infrared absorption spectroscopy (SEIRAS) and density functional theory (DFT) calculations illustrate that the retained oxygen can optimize the adsorption of *OCHO intermediate for the enhanced CO2 RR performance.