Defective MOFs Microreactor with Heterojunction for Selective Methane Photocatalysis via Desorption-Driven Overoxidation Suppression.

Photocatalytic oxidation of methane to methanol oxygenates (CH3OH and CH3OOH) under mild conditions represents a promising approach for methane valorization, yet achieving both high efficiency and high selectivity remains a significant challenge. Herein, a defect-engineered spatial coupling strategy is devised to construct a heterojunction photocatalyst (Def-CuCN/NU) by integrating copper single atoms (Cu SA) anchored on polymeric carbon nitride (CN) into the defective NH2-UiO-66 (Def-NU). The defective MOFs with porous structure and abundant active sites serve as microreactors that enhance methane adsorption and promote methanol desorption, thus promoting the reaction and minimizing the contact of methanol with ·OH radicals and effectively suppressing overoxidation. Additionally, the heterojunction formed between CuCN and Def-NU accelerates charge separation and transport, which renders efficient photocatalytic conversion of methane to methanol oxygenates. Notably, the Def-CuCN/NU catalyst affords a high production rate of 1718 µmol g-1 h-1 for methanol oxygenates under full-spectrum light irradiation at a remarkable selectivity of 96.5%. This study presents the first demonstration of employing defect-engineered MOFs-based heterojunction photocatalysts for the regulation of the reaction pathway to enable highly selective photocatalytic oxidation of CH4.