Photoelectrocatalytic Reduction of CO2 to Paraffin Using p-n Heterojunctions

Nowadays, photoelectrocatalytic (PEC) reduction of CO2 represents a very promising solution for storing solar energy in value-added chemicals, but so far it has been hampered by the lack of highly efficient catalyst of photocathode. Enlightened by the Calvin cycle of plants, here we show that a series of three-dimensional C/N-doped heterojunctions of Zn-x:Co-y@Cu are successfully fabricated and applied as photocathodes in the PEC reduction of CO2 to generate paraffin product. These materials integrate semiconductors of p-type Co3O4 and n-type ZnO on Cu foam to construct fine heterojunctions with multiple active sites, which result in excellent C-C coupling control in reduction of CO2. The best catalyst of Zn-0.2:Co-1@Cu yields paraffin at a rate of 325 mu g.h(-1) under -0.4 V versus saturated calomel electrode without H-2 release. The apparent quantum efficiency of PEC cell is up to 1.95%.