Oxygen‐Rich Carbon Quantum Dots as Catalysts for Selective Oxidation of Amines and Alcohols

Metal‐free carbocatalysis has been widely utilized for aerobic oxidative reactions. Here, we report that oxygen‐rich carbon quantum dots (O‐CQDs) demonstrate a catalytic performance superior to graphene oxide, if used as a metal‐free nanocatalyst for the direct transformation of amines and alcohols, under mild and solvent‐free conditions. O‐CQDs show a yield of 75 % for the oxidative coupling of amine to imine (with 5 wt % catalyst loading) and a conversion of 3.8 % for benzyl alcohol (with 2 wt % catalyst loading). The catalytic activities of thermally treated O‐CQDs are further improved for benzylamine, for example, indicated by a yield of up to 98 % with 4 wt % catalyst loading. In addition, O‐CQDs show a photoenhanced catalytic ability of amine (98 % yield with 5 wt % catalyst loading for 6 h reaction). Characterizations and simulations show that numerous carboxyl oxygen functional groups and unpaired electrons at the edge sites of O‐CQDs are likely involved in the aerobic oxidation of amines. Oxygen‐rich carbon quantum dots (O‐CQDs) demonstrate superior homogeneous catalytic and photoenhanced catalytic performance, if used as a metal‐free nanocatalyst for the direct transformation of amines and alcohols. Characterizations and simulations show that numerous carboxyl oxygen functional groups and unpaired electrons at the edge sites of O‐CQDs are likely involved in the aerobic oxidation of amines.