Highly-selective oxidation of benzyl alcohol to benzaldehyde over Co₁/NC catalysts

Selective oxidation of aromatic alcohols to aldehydes with oxygen is of crucial importance for industrial catalysis, while obtaining high selectivity for easily over-oxidized target products at high conversion is challenging. Herein, Co single atoms supported by nitrogen doped carbon catalysts (Co₁/NC) were successfully prepared by a self-assembly-pyrolysis strategy and applied into the oxidation of benzyl alcohol to benzaldehyde. The reaction results showed that Co₁/NC catalysts exhibited excellent performance compared to Co nanoparticles supported by nitrogen doped carbon catalyst (Co_NPs/NC), among which the 4-Co₁/NC catalyst achieved 95.2% benzyl alcohol conversion and nearly 99.9% benzaldehyde selectivity. Advanced characterization combined with density functional theory calculations demonstrated that the exceptional catalytic performance of Co₁/NC catalysts was attributed to the formed CoN₄ sites, which could moderately activate oxygen and accelerate the desorption of generated benzaldehyde through the electron transfer from Co to the support. The work provides a new insight into the catalysis of single atom sites and their potential applications in alcohol oxidation.