Confining Chainmail-Bearing Ni Nanoparticles in N-doped Carbon Nanotubes for Robust and Efficient Electroreduction of CO2.

Graphical Knight in shining armor : A dual-chainmail-bearing N-doped carbon layers and nanotubes encapsulating a metallic Ni core (Ni@NC@NCNT) showed outstanding stability and selectivity towards CO 2 reduction into CO at moderate potentials, outperforming NCNTs, Ni@NC with single chainmail, Ni@NC/NCNT with Ni@NC sitting on NCNTs, and most state-of-the-art catalysts. This was attributed to enhanced structure robustness, maintained local pH value and boosted CO 2 adsorption capacity and strength. It still remains challenging to simultaneously achieve high stability, selectivity, and activity in CO 2 reduction. Herein, a dual chainmail-bearing nickel-based catalyst (Ni@NC@NCNT) was fabricated via a solvothermal-evaporation-calcination approach. In situ encapsulated N-doped carbon layers (NCs) and nanotubes (NCNTs) gave a dual protection to the metallic core. The confined space well maintained the local alkaline pH value and suppressed hydrogen evolution. Large surface area and abundant pyridinic N and Ni δ + sites ensured high CO 2 adsorption capacity and strength. Benefitting from these, it delivered a CO faradaic efficiency of 94.1 % and current density of 48.0 mA cm −2 at −0.75 and −1.10 V, respectively. Moreover, the performance remained unchanged after continuous electrolysis for 43 h, far exceeding Ni@NC with single chainmail, Ni@NC/NCNT with Ni@NC sitting on the walls of NCNT, bare NCNT and most state-of-the-art catalysts, demonstrating structural superiority of Ni@NC@NCNT. This work sheds light on designing unique architectures to improve electrochemical performances.