Operando Electrochemical Grazing Incidence X-Ray Absorption and Diffraction for CO2 Reduction on Aupd, Pd and Au Electrodes

While the electrochemical reduction of carbon dioxide (CO₂) to viable fuels and chemicals remains an appealing approach to partner with renewable, carbon-neutral energy sources, there remains a lack of fundamental understanding of how the surface of the catalyst changes during electrochemical experiments. Recent reports in the literature indicate that the surface of the catalyst can change drastically under reducing conditions, which suggests that the active catalyst during electrochemical CO₂ reduction conditions may be very different than the catalyst characterized ex situ. Consequently, it is critical to accurately probe the surface of the catalyst in these relevant operando conditions, as it would allow one to observe structural, electronic and orientation changes in the catalyst and to acquire key insights into the CO₂ reduction reaction. Our work reports the design and development of such an experiment at the Stanford Synchrotron Radiation Lightsource (SSRL) using electrochemical grazing incidence x-ray absorption spectroscopy (GIXAS) and electrochemical grazing incidence x-ray diffraction (GIXRD). Using these two techniques, we report changes in the surface electronic structure and lattice orientation of thin film Au₅₅Pd₄₅, Pd and Au catalysts during electrochemical CO₂ reduction.