Direct functionalization of methane into ethanol over copper modified polymeric carbon nitride via photocatalysis

Abstract

Direct valorization of methane to its alcohol derivative remains a great challenge. Photocatalysis arises as a promising green strategy which could exploit hydroxyl radical (·OH) to accomplish methane activation. However, both the excessive ·OH from direct H ₂O oxidation and the neglect of methane activation on the material would cause deep mineralization. Here we introduce Cu species into polymeric carbon nitride (PCN), accomplishing photocatalytic anaerobic methane conversion for the first time with an ethanol productivity of 106 μmol g _cat ⁻¹ h ⁻¹. Cu modified PCN could manage generation and in situ decomposition of H ₂O ₂ to produce ·OH, of which Cu species are also active sites for methane adsorption and activation. These features avoid excess ·OH for overoxidation and facilitate methane conversion. Moreover, a hypothetic mechanism through a methane-methanol-ethanol pathway is proposed, emphasizing the synergy of Cu species and the adjacent C atom in PCN for obtaining C ₂ product.

Abstract

While methane is a simple, abundant feedstock for chemical industry, the selective and facile conversion to more-complex products is challenging. Here, authors show copper-containing polymeric carbon nitride to convert methane to ethanol using light under mild conditions.