Gas Phase Electrolysis of Carbon Dioxide to Carbon Monoxide Using Nickel Nitride as the Carbon Enrichment Catalyst.

Nickel nitride was employed as the carbon enrichment electrocatalyst to reduce CO2 both in the aqueous phase and at the gas-solid interface. In an aqueous electrolyte, the CO Faradaic efficiency reached 85.7% at -0.90 V versus reversible hydrogen electrode with a partial current density of 6.3 mA cm-2. When gaseous CO2 was used as a reactant in a flow cell, the CO Faradaic efficiency increased to 92.5% and current density reached 23.3 mA cm-2. By contrast, metallic Ni and NiO generated predominantly H2. The increased amount of strong base sites in the Ni3N catalyst could enrich CO2 at the catalyst surface, and the utilization of gas phase electrolysis, has cooperatively enhanced reactivity.