Mechanistic Insights into Hydrodeoxygenation of Lignin Derivatives over Ni Single Atoms Supported on Mo2C

Lignin derivatives are one class of attractive alternative feedstocks for the production of renewable biofuels. Herein, hydrodeoxygenation (HDO) of lignin derivatives was carried out using a single-atom catalyst (SAC) comprised of Ni1 SAC on β-Mo2C. A number of lignin-derived compounds have been investigated, and nearly 100% yield of biofuel molecules was converted from various lignin derivatives through the HDO reaction, demonstrating that Ni1/β-Mo2C has remarkable potential for the production biofuels through catalytic hydrodeoxygenation of lignin derivatives. The reaction mechanism of DHE over single-atom catalyst Ni1/β-Mo2C was confirmed based on comprehensive characterizations of catalysts and DFT calculations. Interestingly, the Ni single-atom active sites alter the reaction pathway by shifting the geometry of the adsorbed intermediate from a vertical to horizontal conformation, which lowered the reaction energy barrier and improved the selectivity to biofuel molecules, resulting in extraordinary catalytic activity. This study suggests an avenue for single-atom catalysis in chemical transformations of lignin derivatives into biofuels.