Interstitial nitrogen-induced efficiency alcohol oxidation over heterogeneous N–CoMn2O4 catalyst under visible-light

Abstract

Developing highly efficient and recyclable photocatalysts through harvesting solar light as energy is crucial to oxidation for industrial implementation, especially for simple transition metal oxidic catalysts without precious/heavy/rare metal dopants. Herein, we like to report the use of nitrogen-doped CoMn2O4 oxide (N–CoMn2O4) as a heterogeneous catalyst for efficient oxidation of various alcohols such as p/m/o-methyl-substituted aromatic alcohols, p-substituted aromatic alcohols including electron-donating and electron-withdrawing substituents, heterocycle-based alcohols and secondary aromatic alcohols to the corresponding aldehydes/ketones, under visible light (>420 ​nm) illumination and mild condition of oxygen as oxidant and room temperature. The relation of various Co-based oxides to their catalytic performance was studied. It is shown that the Co2+ species in N–CoMn2O4, obviously increased by the doping of nitrogen, are acted as catalytic active species coupled with the synergistic effect between Co and Mn species for the enhanced visible-light selective oxidation of alcohols to aldehydes. A plausible catalytic mechanism is proposed basis of control experiments and published studies, which suggests that this oxidation process probably occurs on Co2+ sites via an ionic reactive oxygen species pathway and 1O2 and O2·− species are the reactive oxygen species. This simple transition metal oxide-catalyzed aerobic oxidation provides a green alternative for the manufacture of aldehydes/ketones from alcohols.