Construction of Porphyrin Porous Organic Cage as a Support for Single Cobalt Atoms for Photocatalytic Oxidation in Visible Light

The construction of an appropriate support for a single atom catalyst plays an important role in delivering a high catalytic performance. However, most reported host materials suffer the drawbacks of low photostability and limited visible light absorption. Herein, we report a porous organic cage as a high-quality support for single metal atoms by a facile stepwise nucleophilic substitution approach. Thanks to its intrinsic advantages of extended visible light absorption, suppressed charge recombination, and improved electron transfer, the obtained single Co atoms anchored organic cage (CoP@POC) demonstrates a prominent photocatalytic efficiency for oxidation of amines into imines in visible light. An excellent reaction conversion and selectivity up to 99%, associated with a turnover frequency (TOF) of 1389 h–1 and 22 989 mmol g–1 h–1 are achieved based on organic cage and single Co atoms, respectively, which outperforms most reported photocatalysts. Moreover, a negligible conversion decrease in 5 repeating cycles and no photobleaching after the reaction was detected, implying a remarkable photostability of CoP@POC.