Atomically dispersed cobalt on graphitic carbon nitride as a robust catalyst for selective oxidation of ethylbenzene by peroxymonosulfate

Abstract

The development of a highly efficient strategy for the activation of the C–H bond in hydrocarbons is one of the most challenging tasks facing the chemical industries. The synthesis of novel catalysts with atomically dispersed active centers is highly desirable to achieve the maximized atom efficiency. Here we report the controllable preparation of a Co-based single-atom catalyst anchored on a graphitic carbon nitride support (SACo@g-C₃N₄) with 3.17 wt% Co content, which is successfully applied for the selective oxidation of ethylbenzene (EB) to derive acetophenone (AcPO) via the activated peroxymonosulfate (PMS) oxidant. The Co atoms are chemically bonded with the N atoms of g-C₃N₄ and present exceptional stability and reusability to resist the applied acidic-oxidative environment. Both the EB conversion and AcPO selectivity were over 95% in this highly selective SACo@g-C₃N₄/PMS system under mild reaction conditions. The selective conversion of EB into AcPO is attributed to the oxidative radicals generated from the decomposition of PMS molecules via the electron transfer between Co atoms and PMS. Sulfate radicals (SO₄˙⁻) make a greater contribution than others to activate the C–H bond in EB oxidation. This work uncovers a facile and scalable approach for the synthesis of a robust Co-based single atom catalyst (SAC) on a g-C₃N₄ support and unveils its potential in the oxidation of hydrocarbons via a highly efficient and environmentally benign PMS activation.