Photoelectrocatalytic Reduction of CO2 to Paraffin Using p-n Heterojunctions

Nowadays, photoelectrocatalytic (PEC) reduction of CO 2 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 CO 2 to generate paraffin product. These materials integrate semiconductors of p-type Co 3 O 4 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 CO 2 . The best catalyst of Zn 0.2 :Co 1 @Cu yields paraffin at a rate of 325 μg·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%.