Pathway Alteration of Water Splitting via Oxygen Vacancy Formation on Anatase Titanium Dioxide in Photothermal Catalysis
Zheng Li, Xuhan Zhang, Li Zhang, Chenyu Xu, Yanwei Zhang
Abstract
Solar-induced photothermal catalysis of water splitting is a promising method to produce hydrogen and could be promoted by surface defects, especially oxygen vacancies on the surfaces of metal oxides. The interaction between water and surface is likely to lead to the formation of oxygen vacancies and alters the pathway of overall water splitting. The complete free energy profiles of the two different pathways on the anatase TiO2(101) surface are calculated based on density functional theory, and hydrogen evolution is found to be the rate-determining step. The doping of Fe and Cu both reduces the energy barriers of oxygen vacancy formation but has different effects on hydrogen evolution on oxygen vacancies. The balance between the formation and reactivity of surface oxygen vacancies is the key factor for the pathway preference for water splitting. Therefore, the two different pathways of overall water splitting on the surfaces of metal oxides should be taken into consideration for photothermal catalyst design and screening.