Identifying the Activity Origin of a Single-Atom Au1/Nb2O5 Catalyst for Hydrodeoxygenation of Methylcatechol: A Stable Substitutional Au+ Site

Developing effective and stable single-atom catalysts (SACs) is a significant but challenging task, which requires the identification of single-atom metal sites and their configurations. Herein, we report a single-atom Au1/Nb2O5 catalyst for the hydrodeoxygenation of methylcatechol, a lignin model compound, which maintains stability in five consecutive conversions. Combined with the density functional theory (DFT) calculations, the Au+ located at the Nb lattice site with two concomitant oxygen vacancies (Au@Nbv–2Ov) is identified as the thermodynamically favorable Au single-atom species and dominates the activity for molecular H2 dissociation via a heterolytic mechanism. Moreover, the presence of oxygen vacancies in Au@Nbv–2Ov facilitates the adsorption of methylcatechol, resulting in efficient cleavage of C–O bonds. Consequently, we design a catalyst with more Au+ sites, which exhibits enhanced catalytic activity. This work systematically elucidates the structure–activity relationship and provides a promising strategy to optimize SACs for the hydrodeoxygenation reaction.