Boosting Cascade Electron Transfer for Highly Efficient CO_2 Photoreduction

摘要

Artificial photosynthesis converting carbon dioxide into chemical fuels with ahigh added value is a promising solution to both fossil fuel shortage/pollutionand global climate change; however, the development of highly efficient photocatalyststoward this goal is still largely bereft of fresh ideas. Herein, wepropose a “cascade electron transfer” strategy through spurring both interfacialand inner electron transfer rates for a 0D/2D photocatalyst of CsPbBr_3/CuTCPPmetal organic framework (MOF). Upon photoexcitation, the heterojunctionstructure with an appropriate band alignment facilitates an ultrafast interfacialelectron transfer rate of 1.4 ps from CsPbBr3 segment to CuTCPP MOF andsubsequent ultrafast internal electron transfer of 21 ps from CuTCPP ligand to theCu node within the enlarged 2D framework. The efficient electron transferensures efficient charge separation favorable for photocatalytic reactions: Thephotocatalyst exhibits an outstanding yield of 47.2 μmol g~(-1) h~(-1) (CO and CH_4combined) superior to previous reports. Rational design of hierarchical heterojunctionswith matching electronic bandgap not only expedites cascade chargetransfer but also prevents holes from recombining with electrons or oxidizing thephotocatalysts without the necessity of sacrificial reagents. This work thusprovides useful insight for boosting photocatalytic efficacy from a dynamicperspective.