Rational design of hollow nitrogen-doped carbon supported nickel nanoparticles for efficient electrocatalytic CO2 reduction

Electrocatalytic carbon dioxide reduction reaction (CO2RR) is a promising approach to achieving a carbon-neutral cycle and producing valuable fuels and chemicals. Herein, we develop a nickel nanoparticle embedded in a hollow nitrogen-doped carbon ([email protected]) catalyst with the optimum carbon oxide (CO) Faradaic efficiency of 93.3% at -0.79 V versus reversible hydrogen electrode (vs. RHE). A series of controlled experiments demonstrated that the PDA-assisted derivatized hollow nitrogen-doped carbon support facilitates the diffusion of CO2 molecules. As proton acceptors, the nickel active sites promote the proton-coupled electron transport process of electroreduction of CO2 to CO. Additionally, [email protected] was performed as a bifunctional catalyst, and the coupled anodic methanol oxidation reaction (MOR) can significantly reduce the voltage, about 424 mV at 10 mA cm-2 (versus oxygen evolution reaction, OER). For a two-electrode system, the Faradaic efficiency of CO was maintained above 90% at a wide voltage window (2.1 ~ 3.1 V), with a maximum value of 98.7% at 2.7 V and a current density of 11.14 mA cm-2. This work provides an efficient strategy to obtain lower CO2RR voltage while acquiring high value-added formate from the anode.