Catalytic Intermediates of CO2 Hydrogenation on Cu(111) Probed by In Operando Near‐Ambient Pressure Technique

The in operando monitoring of catalytic intermediates is crucial for understanding the reaction mechanism and for optimizing the reaction conditions to improve the efficiency of the catalytic protocol; however, until now, this has remained a daunting challenge. Herein, we investigated the interaction of CO2 and H2 with the Cu(111) surface in a CO2 hydrogenation model system by using the in operando technique of near‐ambient pressure X‐ray photoelectron spectroscopy, which is further assisted by ultraviolet photoemission spectroscopy and low‐energy electron diffraction (LEED) measurements. These techniques allowed the direct observation of CO2 dissociation into CO+O on the Cu(111) surface and the adsorption of O on the surface at room temperature. The intermediate HCOO− was unambiguously detected in the CO2+H2 environment, which corroborated the formate pathway for methanol formation on the Cu(111) surface. We further found that O coverage can prevent the build up of graphitic carbon on the Cu surface. By taking advantage of the competitive interplay between Cu−O and graphitic carbon, we have proposed a feasible strategy for inhibition of the formation of graphitic carbon by tuning the CO2 and H2 partial pressures, which may contribute to sustaining the active Cu catalyst under the reaction conditions. Methanol synthesis on catalytic Cu surface: Near‐ambient pressure X‐ray photoelectron spectroscopy measurements unravel the formate pathway for methanol synthesis on the Cu(111) surface and reveal a competing interplay between the Cu−O and graphitic carbon, which may provide a feasible strategy for inhibiting the formation of graphitic carbon by tuning the partial pressures of CO2 and H2 (see picture).