Nitrogen-doped carbon-encompassed Ni nanoparticles prepared from Ni (II) cation-exchanged metal organic framework for efficient electrochemical CO2 reduction

Abstract

Carbon layer-encompassed nickel nanoparticles of core–shell structure (designated as Ni NPs@NC) show notable advantages toward electrochemical carbon dioxide reduction reaction (CO₂RR). Core-shell structured Ni NPs@NC nanoparticles anchored on the carbon matrix have been conveniently built from a cationic metal–organic framework (CPM-72 herein) which incorporates the Ni²⁺ cations through the cation exchange before high-temperature pyrolysis. The designed Ni NPs@NC catalyst exhibited impressive CO₂RR performance which could efficiently convert CO₂ into CO (carbon monoxide). In the H-type cell, a maximal CO faradaic efficiency (FE) of 86.4% was achieved at −0.8 V (vs. RHE) with a high CO partial current density (j_co) of −11.0 mA cm⁻². In the flow cell device, the CO FE was further improved to 98.6% with the enhanced j_co of −38.7 mA cm⁻². Finally, Zn-CO₂ battery test also delivered a peak power density of 0.39 mW cm⁻² at 2.65 mA cm⁻².