Partially Nitrided Ni Nanoclusters Achieve Energy‐Efficient Electrocatalytic CO<sub>2</sub> Reduction to CO at Ultralow Overpotential
Runyao Zhao, Yiding Wang, Guipeng Ji, Jiajun Zhong, Fengtao Zhang, Meifang Chen, Shengrui Tong, Peng Wang, Zhonghua Wu, Buxing Han, Zhimin Liu
Abstract
Abstract Electrocatalytic CO 2 reduction reaction (CO 2 RR) offers a promising strategy to lower CO 2 emission while producing value‐added chemicals. A great challenge facing CO 2 RR is how to improve energy efficiency by reducing overpotentials. Herein, partially nitrided Ni nanoclusters (NiN x ) immobilized on N‐doped carbon nanotubes (NCNT) for CO 2 RR are reported, which achieves the lowest onset overpotential of 16 mV for CO 2 ‐to‐CO and the highest cathode energy efficiency of 86.9% with CO Faraday efficiency >99.0% to date. Interestingly, NiN x /NCNT affords a CO generation rate of 43.0 mol g −1 h −1 at a low potential of −0.572 V (vs RHE). DFT calculations reveal that the NiN x nanoclusters favor *COOH formation with lower Gibbs free energy than isolated Ni single‐atom, hence lowering CO 2 RR overpotential. As NiN x /NCNT is applied to a membrane electrode assembly system coupled with oxygen evolution reaction, a cell voltage of only 2.13 V is required to reach 100 mA cm −2 , with total energy efficiency of 62.2%.