Highly Efficient Nickel, Iron, and Nitrogen Codoped Carbon Catalysts Derived from Industrial Waste Petroleum Coke for Electrochemical CO2 Reduction

Electrochemical CO2 reduction reaction (ECO2RR) is a potentially promising way of producing sustainable energy by converting CO2 into fuels or useful chemicals using alternative power sources such as solar and wind. However, finding cheap and abundant materials with a high catalytic activity for CO2 reduction is critical for future larger-scale applications of ECO2RR. Herein, we used petroleum coke (PC), an industrial waste, as the carbon source for preparing highly efficient ECO2RR catalysts. By doping nickel and nitrogen into oxidized PC (Ni–N-PC), an ∼97% Faradaic efficiency of CO production has been achieved with a current density of ∼18 mA/cm2 at −0.8 V versus the reversible hydrogen electrode. By further doping iron into the Ni–N-PC catalyst (forming Fe/Ni–N-PC), a 90% Faradaic efficiency of CO and a 20 mA/cm2 CO partial current density were achieved. The ECO2RR performance of the above PC-based catalysts was comparable to that of traditional graphite-based catalysts, but the former is an industrial waste and costs little. Findings from this work provide insight into transfer of industrial waste into a carbon precursor under similar treatment to synthesize efficient ECO2RR catalysts.