Structures and stability of adsorbed methanol on TiO2 (110) surface studied by ab initio thermodynamics and kinetic Monte Carlo simulation

The structures and stability of adsorbed methanol on TiO2(110) surface have been extensively studied because of its application for direct hydrogen production and promoting hydrogen production in photocatalysis. In this work, combined with ab initio thermodynamics and kinetic Monte Carlo (KMC), a detailed microscopic picture of methanol adsorption structure on TiO2(110) surface at different conditions is mapped out for the first time. The thermodynamics analysis based on the density functional theory calculations shows that the methanol adsorption at coverage of 2/3 ML is prevailed at a very wide range of temperatures and pressures. The simulated temperature-programmed desorption (TPD) based on KMC indicates that the full monolayer adsorption methanol desorbs at about 150 K and the methanol dimer at a coverage of 2/3 ML is stable up to 250 K. At higher temperature, the methanol dimer becomes unstable and decomposes to the monomer, which desorbs from the surface at 350 K. The present simulated results agree well with the experimental TPD results