Anchoring single Ni atoms on CeO2 nanospheres as an efficient catalyst for the hydrogenolysis of lignin to aromatic monomers

• Single-atom Ni catalysts were successfully prepared by a facile hydrothermal method. • The oxygen vacancies on the CeO 2 nanospheres are crucial for anchoring the Ni atoms. • The single-atom catalyst promotes the conversion of lignin to its aromatic monomers. Lignin is the most abundant renewable aromatic resource in nature; thus, the development of an efficient and economical catalysts that can depolymerize lignin into value-added aromatic monomers is highly desirable. Here, we report a single-atom Ni catalyst ( x Ni/CeO 2 -S, where x represents the Ni loading), in which the single-atom Ni sites are anchored to the oxygen vacancies on CeO 2 nanospheres, for the conversion of cellulolytic enzyme lignin (CEL) via depolymerization and hydrodeoxygenation. The 1.0Ni/CeO 2 -S catalyst performed the best, achieving a lignin oil (LO) and maximum monomer yield of 84.3 wt% and 32.6 wt%, respectively; a higher heat value of 31.64 MJ/Kg is achieved for LO compared to 23.03 MJ/Kg for CEL. Thus, single-atom nickel catalyst exhibited excellent activity and stability in promoting the depolymerization of lignin. These results validate the viability of single-atom metal catalysts for the conversion of lignin resources.