Selective light-driven methane oxidation to ethanol

Abstract

Methane (CH 4 ) photocatalytic upgrading to value-added chemicals, especially C 2 products, is significant yet challenging due to sluggish energy/mass transfer and insufficient chemical driven-force in single photochemical process. Herein, we realize solar-driven CH 4 oxidation to ethanol (C 2 H 5 OH) on crystalline carbon nitride (CCN) modified with Cu 9 S 5 and Cu single atoms (Cu 9 S 5 /Cu-CCN). The integration of photothermal effect and photocatalysis overcomes CH 4 -to-C 2 H 5 OH conversion bottlenecks, with Cu 9 S 5 as a hotspot to convert solar-energy to heat. In-situ characterizations demonstrate that Cu single atoms play as electron acceptor for O 2 reduction to ·OOH/ · OH, while Cu 9 S 5 acts as hole acceptor and site for CH 4 adsorption, C − H activation, and C − C coupling. Theoretical calculations demonstrate that Cu 9 S 5 /Cu-CCN reduces C − C coupling energy barrier by stabilizing ·CH 3 and ·CH 2 O. Impressively, C 2 H 5 OH productivity reaches 549.7 μmol g –1 h –1 , with selectivity of 94.8% and apparent quantum efficiency of 0.9% (420 nm). This work provides a sustainable avenue for CH 4 conversion to value-added chemcials.