Non-oxidative Coupling of Methane: N-type Doping of Niobium Single Atoms in TiO₂ -SiO₂ Induces Electron Localization

Photodriven nonoxidative coupling of CH₄ (NOCM) is an attractive potential way to use abundant methane resources. Herein, an n-type doped photocatalyst for NOCM is created by doping single-atom Nb into hierarchical porous TiO₂ -SiO₂ (TS) microarray, which exhibits a high conversion rate of 3.57 μmol g^-1  h^-1 with good recyclability. The Nb dopant replaces the 6-coordinated titanium on the (1 0 1) plane and forms shallow electron-trapped surface polarons along [0 1 0] direction and the comparison of different models proves that the electron localization caused by the n-type doping is beneficial to both methane activation and ethane desorption. The positive effect of n-type dopant on CH₄ conversion is further verified on Mo-, W- and Ta-doped composites. In contrast, the doping of p-type dopant (Ga, Cu, Fe) shows a less active influence.