Tunable Syngas Production through CO2 Electroreduction on Cobalt-Carbon Composite Electrocatalyst.

Controllable concomitant production of CO and H2 (syngas) during electrochemical CO2 reduction reactions (CO2RR) is expected to improve the commercial feasibility of the technology to mitigate CO2 emissions as the generated syngas can be converted into useful chemicals using the commercial Fischer-Tropsch (FT) process. Herein, we demonstrate the ability of a Co single-atom-decorated N-doped graphitic carbon shell-encapsulated cobalt nanoparticle electrocatalyst (referred as Co@CoNC-900) to controllably produce syngas at low overpotentials during CO2RR. Through the engineering and modulation of dual active sites for CO2RR (modified carbon shell with encapsulated Co) and hydrogen evolution reaction (Co-N4 moieties) within Co@CoNC by varying the annealing temperature, we are able to tune the H2: CO ratio from 1: 2 to 1: 1 to 3: 2 over a wide range of applied potentials (-0.5 V to -0.8 V versus reversible hydrogen electrode, RHE). This versatile control of H2: CO ratio in CO2RR reaction brings up significant opportunity of using CO2 and H2O and renewable energy for producing a range of chemicals.