Photoelectron Storage at the WO3/TiO2 Interface: Modeling in Ambient Conditions from First-Principles Calculations

Using first-principles calculations, we showed that the monoclinic WO3(001) preferentially forms a reconstructed monolayer on the anatase TiO2(001) surface. We thoroughly examined the structure of the WO3/TiO2 surface under ambient conditions, i.e., in equilibrium with gas-phase O2/H2O or H2/H2O under a range of pressure and temperature or in aqueous solution under a range of pH and electrochemical potential. Based on the WO3/TiO2 surface structures at different potentials, we proposed the proton-coupled electron-transfer (PCET) reaction pathway during charging and oxygen reduction reaction (ORR) pathways during discharging, which account for its reversible electron storage ability. With electronic structure analysis, we depicted the charge separation effect of WO3 on TiO2 and the electron storage effect of WO3.