Metal–Organic Framework Decorated Cuprous Oxide Nanowires for Long-lived Charges Applied in Selective Photocatalytic CO₂ Reduction to CH₄

Improving the stability of cuprous oxide (Cu₂O) is imperative to its practical applications in artificial photosynthesis. In this work, Cu₂O nanowires are encapsulated by metal–organic frameworks (MOFs) of Cu₃(BTC)₂ (BTC=1,3,5-benzene tricarboxylate) using a surfactant-free method. Such MOFs not only suppress the water vapor-induced corrosion of Cu₂O but also facilitate charge separation and CO₂ uptake, thus resulting in a nanocomposite representing 1.9 times improved activity and stability for selective photocatalytic CO₂ reduction into CH₄ under mild reaction conditions. Furthermore, direct transfer of photogenerated electrons from the conduction band of Cu₂O to the LUMO level of non-excited Cu₃(BTC)₂ has been evidenced by time-resolved photoluminescence. This work proposes an effective strategy for CO₂ conversion by a synergy of charge separation and CO₂ adsorption, leading to the enhanced photocatalytic reaction when MOFs are integrated with metal oxide photocatalyst.