MOF-derived nanoporous Ni NPs@NC micro-flower catalysts for the efficient electrocatalytic reduction of CO2 to CO

Nickel nanoparticles (Ni NPs) encapsulated in carbon shells have shown promise in the electrochemical reduction of CO 2 to CO. The electronic regulation of the interface between Ni NPs and carbon shells plays a crucial role in reducing the energy barrier of the CO reaction path. We report the formation of a catalyst with hierarchical porosity (Ni NPs@NC) using a high-surface-area 3D Ni-MOF as the precursor. By correlating the pyrolysis temperature with structural changes and catalytic efficiency, structure-activity relationships were established. Because of the confined encapsulation of the Ni NPs by the N-doped carbon layer, the framework does not collapse during pyrolysis but also produces a high-density of exposed Ni-N active sites and better mass transport paths. Notably, the Ni NPs@NC-800 sample had an outstanding electrocatalytic performance for CO 2 reduction, achieving a maximum Faradaic Efficiency (FE) of 93% at −0.8 V vs RHE, and maintaining over 90% efficiency even after 48 h of continuous operation. Raman spectroscopy showed that the interface between the Ni NPs and the carbon shell play a critical role in stabilizing the critical COOH intermediate, promoting CO desorption and inhibiting the competing hydrogen evolution reaction. This work may provide insight for producing catalysts for efficient electrochemical CO 2 reduction over a wide potential range. Download: Download high-res image (53KB) Download: Download full-size image