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.

Dual Role of Pyridinic-N Doping in Carbon-Coated Ni Nanoparticles for Highly Efficient Electrochemical CO2 Reduction to CO over a Wide Potential Range

“…All these results can confirm the intensified CO 2 adsorption caused by pyridinic-N, which will contribute to sufficient CO with the catalyst surface, thus relieving the mass transfer limitation to the CO 2 RR under a high reduction potential. 29,54 This effect is further verified by the LSV curves of NC@Ni/C-60 at varied KHCO 3 concentrations (Figure 4f). As revealed by a previous study, the increase of KHCO 3 concentration will strengthen the dissolved CO 2 concentration ([CO 2 ]).…”

“…DFT calculations further confirm that the binding energy of CO 2 with pyridinic-N coated Ni (0.063 eV) is higher than that of CO 2 with pure Ni (0.024 eV), carbon-coated Ni (0.030 eV), graphitic-N-coated Ni (0.035 eV), and pyrrolic-N-coated Ni (0.050 eV) (Figure S10). All these results can confirm the intensified CO 2 adsorption caused by pyridinic-N, which will contribute to sufficient CO 2 interacting with the catalyst surface, thus relieving the mass transfer limitation to the CO 2 RR under a high reduction potential. , This effect is further verified by the LSV curves of NC@Ni/C-60 at varied KHCO 3 concentrations (Figure f). As revealed by a previous study, the increase of KHCO 3 concentration will strengthen the dissolved CO 2 concentration ([CO 2 ]) .…”

“…To further identify the active sites of NC@Ni/C in CO 2 RR, PO 4 3− anions were employed to selectively block the surface pyridinic-N sites. 54 This poisoning treatment leads to a featureless CO 2 RR performance of NC@Ni/C-60 (Figure S8c,d), implying that the pyridinic-N species make a great contribution to the reaction. Recently, NiN x single sites have been proved to be effective for CO 2 RR to produce CO. 17,27 To exclude this possibility, some control experiments were conducted.…”

“…To further identify the active sites of NC@Ni/C in CO 2 RR, PO 4 3– anions were employed to selectively block the surface pyridinic-N sites . This poisoning treatment leads to a featureless CO 2 RR performance of NC@Ni/C-60 (Figure S8c,d), implying that the pyridinic-N species make a great contribution to the reaction.…”

Review on Heteroatom Doping Carbonaceous Materials Toward Electrocatalytic Carbon Dioxide Reduction

“…In recent years, Ni-based carbon materials have also been successfully synthesized. In 2021, Niu et al [77] prepared a double-chain nickel-based catalyst (Ni@NC@ NCNT) by solvothermal evaporation calcination. The performance of Ni@NC@NCNT for CO 2 RR is much better than that of single-chain Ni@NC.…”