Enhancing CO2 Electroreduction to Methane with Cobalt Phthalocyanine and Zinc-Nitrogen-Carbon Tandem Catalyst.

Developing copper-free catalysts for CO 2 conversion into hydrocarbons and oxygenates is highly desirable for electrochemical CO 2 reduction reaction (CO 2 RR). Herein, we report a cobalt phthalocyanine (CoPc) and zinc-nitrogen-carbon (Zn-N-C) tandem catalyst for CO 2 RR to CH 4 . This tandem catalyst shows more than 100 times enhancement in CH 4 /CO production rate ratio compared with CoPc or Zn-N-C alone. Density functional theory calculations and electrochemical CO reduction reaction results suggest that CO 2 is firstly reduced into CO over CoPc and then CO diffuses onto Zn-N-C for further conversion into CH 4 over Zn-N 4 site, decoupling complicated CO 2 RR pathway on single active site into a two-step tandem reaction. Moreover, mechanistic analysis indicates that CoPc not only generates CO but also enhances the availability of *H over adjacent N sites in Zn-N 4 , which is the key to achieve the high CH 4 production rate and understand intriguing electrocatalytic behavior distinctive to copper-based tandem catalysts.