C1 Conversions over Well-Defined Model Surfaces Probed with Ambient Pressure X-ray Photoemission Spectroscopy

Abstract

The sustainable utilization technology for carbon dioxide (CO2) still has many drawbacks of CO2 activation under mild conditions in industrial processes because of the high activation energy barrier of CO2. In surface science, we have focused on the revealing CO2 activation process over well-defined model catalysts, considering the issues of pressure and material gaps. One of the emerging characterization techniques, ambient pressure X-ray photoelectron spectroscopy (AP-XPS), is unveiling the momentous reaction steps of CO2 dissociation and sequentially formed intermediate species at the gas-solid interface. The probed chemical bonding or binding information provides critical evidence for understanding CO2 activation towards value-added chemicals at the molecular level. In this talk, I will discuss in situ surface catalysis studies on the conversion of light carbon (C1) molecules into methane or methanol. Particularly, I will highlight the physical behavior of nickel (Ni)- or copper (Cu)-based metal-oxide catalysts for facile carbon diffusion and transfer at the interface. The modified surface geometries and electronic states by surface alloy formations may induce facile molecular conversions for the dissipation of hydrogen or coupling of carbon-terminated intermediates. The synchrotron-based AP-XPS technique can resolve the difference in chemical binding species of molecularly adsorbed CO2 and dissociated adsorbates by the cleavage of O=C=O bonds at ambient pressures. In addition, the characteristic electron transitions among X-ray absorption edges could give us useful information to interpret unusual catalytic processes. Those systematic in situ observations will shed light on the novel catalyst design and advances in energy science.