Enhancing CO2 Electroreduction with Au/Pyridine/Carbon Nanotubes Hybrid Structures

Selective electrochemical reduction of CO2 by using renewable electricity has received considerable attention because of the potential to convert a harmful greenhouse gas into useful chemicals. A high-performance electrocatalyst for CO2 reduction is constructed based on metal nanoparticles/organic molecule hybrid materials. On the nanoscale, Au nanoparticles are uniformly anchored on carbon nanotubes to afford substantially increased current density, improved selectivity for CO, and enhanced stability. On the molecular level, the catalytic performance is further enhanced by introducing axial pyridine groups to the surface of the carbon nanotubes. The resulting hybrid catalyst exhibits around 93 % faradaic efficiency for CO production over a wide potential range (-0.58 to -0.98 V), a high mass activity of 251 A gAu-1 at -0.98 V in aqueous solution at near-neutral pH, and strong stability with continuous electrolysis for 10 h at -0.58 V. DFT calculations indicate that the synergistic effects of Au and axial pyridine could dramatically stabilize the key intermediate (*COOH) formed in the rate-limiting step of CO2 reduction, which effectively lowers the overpotential.