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

Abstract

It still remains challenging to simultaneously achieve high stability, selectivity, and activity in CO2 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 Niδ+ sites ensured high CO2 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.