Revealing the gas sensitive stability of formate species during CO2 hydrogenation

Abstract

A series of in situ time-resolved diffuse reflectance Fourier transform spectroscopy (DRIFTS)-mass spectrometry experiments were performed on a supported Cu/CeO₂ catalyst. It is revealed that formates are formed during the reverse water–gas shift reaction and are more stable in a hydrogen flow than in an argon flow. Operando DRIFTS, quasi in situ X-ray photoelectron spectroscopy (XPS), and in situ time-resolved Raman spectroscopy analysis suggest that the more abundant oxygen vacancies for Cu/CeO₂ in the hydrogen-rich environment are responsible for the stabilization of formates. Therefore, attention should be paid to interpreting the reactivity of key reactive intermediates with H₂ when determining the reaction pathway of the CO₂ hydrogenation reaction, as the number of surface oxygen vacancies may vary under different testing conditions.