In Situ Growth of Metal‐Organic Layer on Polyoxometalate‐etching Cu2O to Boost CO2 Reduction with High Stability

Abstract Low‐cost Cu 2 O with a suitable band gap holds great potential for solar utilization. However severe photocorrosion and weak CO 2 capture capability have significantly hindered their application in artificial photosynthesis. Herein, polyoxometalate (POM)‐etching and in situ growth of metal–organic framework (MOF) can simultaneously incorporate electron‐sponge and HKUST protective layer into Cu 2 O. The resulting ternary composites Cu 2 O@POM@HKUST‐n (POM=PMo 12 O 40 and PW 12 O 40 ) with dual hetero‐interfaces can efficiently convert CO 2 to HCOOH with 5226 μmol g −1 yield, over 5 and 55 times higher than that of Cu 2 O (1010 μmol g −1 ) and Cu 2 O@HKUST (95.02 μmol g −1 ). In situ XPS and DFT studies reveal that Cu mainly existed in the form of Cu 2 O and Cu‐MOF, while a unique Cu x+ (1<x≤2) surface layer formed upon the Cu 2 O matrix surrounding POMs for CO 2 absorption and activation. Systematic investigations demonstrate that the electron‐sponge can efficiently capture electrons from excited Cu 2 O to promote the generation of a Cu x+ surface layer, while the closely surface‐coating metal‐organic layer can act as protective layer and CO 2 adsorbent. This dual function concurrently contributes to promote photocatalysis and prevent Cu 2 O degradation. Remarkably, the composites exhibit much enhanced photochemical stability and can be used for over 60 h without noticeable activity loss.