Study of CO2 adsorption/dissociation on PtGa(111) alloy

Abstract

Over the years, various catalytic materials have been searched and tested for maximum utilization of CO2 as CO2 has been pointed out as a primary reason of global warming issue. From this perspective, a PtGa alloy, which exhibits strong oxidation and corrosion resistance from chemical reactions, is tested for CO2 adsorption/dissociation process utilizing Ambient-pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Low Energy Electron Diffraction (LEED). As PtGa surface is annealed under UHV condition, the amount of Ga starts to increase, reaching the Pt to Ga ratio of 1:2. In addition, the binding energy of Pt 4f and Ga 3d core level shift towards higher binding energy direction while Pt and Ga metal peak decrease. Below 0.02 mbar of CO2 gas pressure, the surface Pt and Ga compositions remain same. Then, when CO2 pressure is reached at 0.2 mbar with increased temperature, the enhancement of Ga oxide peak is observed in Ga 3d core level, indicating the sign of CO2 dissociation. In O 1s and C 1s core level spectra, the sign of CO2 dissociation is also witnessed. Over 400 K, the oxidation states of Ga starts to change from Ga2Ox to Ga2O3. When temperature is reached at 600 K, a stable Ga2O3 is formed on the surface.