Unraveling Surface Chemistry of SnO2 Through Formation of Charged Oxygen Species and Oxygen Vacancies

Understanding the properties of the adsorbed oxygen species on the SnO2 surface is essential in describing the reaction mechanisms responsible for gas sensing applications. Density functional theory (DFT) calculations were performed to shed light on these mechanisms by exploring the energetics of molecular, atomic, and dissociative oxygen adsorption on various types of reduced, defective, and stoichiometric SnO2(110) surfaces. Charge analysis distinguished various forms of charged oxygen species on the surface. The calculations identified the existence of O_2^(2-), O_2^-, and O^(2-) on the reduced surface and O_2^(2-), O^-, and O^(2-) on the defective and the oxidized surfaces. The role of oxygen vacancies in recognizing the adsorption modes and relevant properties is demonstrated. The described electronic structure in this work supports experimental findings.