Hydrogenolysis of Lignin Model Compounds on Ni Nanoparticles Surrounding the Oxygen Vacancy of CeO 2

The cleavage of C–O bonds presents the crucial step for realizing the depolymerization of lignin. Herein, we report that Ni nanoparticles (NiNPs) supported on CeO 2 with oxygen vacancies (O v ) show high activity and selectivity in hydrogenolysis of C–O bonds of diphenyl ether (DPE, a lignin model compound), while single-site Ni (SSNi) is nearly inactive in the reaction. Temperature-programmed desorption (TPD) demonstrates that both DPE and H 2 can be adsorbed and activated on NiNPs. Density functional theory (DFT) calculation further indicates that the NiNPs are more reactive for H 2 and DPE because the O v at the interface between NiNPs and CeO 2 can greatly enhance the adsorption of DPE, but no adsorption of DPE on SSNi was observed. It is identified that the Ni atoms of NiNPs neighboring the O v of CeO 2 are the catalytic sites of the Ni/CeO 2 catalyst for the efficient cleavage of C–O bonds in lignin model compounds. This work highlights that the Ni sites neighboring the O v of CeO 2 can act as efficient active sites for rupturing the C–O bonds in lignin models, which can be conducive to the rational design of metal-supported catalysts, especially for the hydrogenolysis of C–O bonds in biomass conversion.