Single Ti<sup>3+</sup> Ion Catalyzes NO Reduction on Stoichiometric Titanium Oxide Cluster Anions (TiO<sub>2</sub>)<sub><i>n</i></sub><sup>–</sup> (<i>n</i> = 1–11)
Jiaojiao Chen, Yun-Zhu Liu, Qing‐Yu Liu, Xiao‐Na Li, Sheng‐Gui He
Abstract
Titanium dioxide (TiO2) is an important oxide material owing to its extraordinary catalytic reactivity in a wide range of applications. Different species on the surface of TiO2 have been proposed to contribute to its reactivity, while the intriguing catalytic role of a Ti3+ ion has not been substantiated to date. Herein, benefiting from state-of-the-art mass spectrometry and quantum chemical calculations, we demonstrated that an exposed single Ti3+ ion on stoichiometric titanium oxide clusters (TiO2)n– (n = 1–11) works independently to catalyze NO reduction by CO. The single-electron mechanism to reduce NO into N2O was discovered, and an atomic oxygen radical (O•–) on products (TiO2)nO– that is highly reactive (e.g., in CO oxidation) was created. This finding is pivotal for providing a fundamental strategy to utilize an isolated Ti3+ ion on the surface of TiO2 and points out that this catalytic behavior can be a potential pathway in the atmosphere for pollutant removal.