Methyl Radical Dominated Highly Selective Methane Oxidation to Liquid Oxygenates.

Selective oxygenation of methane to value-added chemicals remains a great challenge due to the higher oxidation tendency of products than inert methane that leads to uncontrollable overoxidation. Herein, a strategy of photoinduced direct generation of methyl radicals (•CH3) from methane is proposed. Unlike traditional mechanisms that rely on highly oxidative activators (such as •OH radicals), this approach enables controllable methane oxygenation and properly avoids the overoxidation of formed products to CO2. To this end, Pt single-atom-decorated ZnO (Pt1/ZnO) is assembled as the proof-of-concept photocatalyst, in which Pt single atoms serve as both hole trapping and methane activation sites; the yielded •CH3 with an enriched surface coverage then drives the radical chain process by first incorporating the environmentally benign molecular oxygen (or its derivative O2•-), achieving a remarkable liquid product selectivity and formaldehyde yield of 95% and 2.98 mmol g-1 h-1, respectively, with a record quantum efficiency of 14.14% at 350 nm.