College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Hangzhou, 311300, Zhejiang, People's Republic of China.
School of Physical Science and Technology, Ningbo University, Ningbo, 315211, Zhejiang, People's Republic of China.
Sci Rep. 2023 Jun 19;13(1):9926. doi: 10.1038/s41598-023-36945-0.
Carbon-based single-atom catalysts (SACs) for electrochemical nitrogen reduction reaction (NRR) have received increasing attention due to their sustainable, efficient, and green advantages. However, at present, the research on carbon nanotubes (CNTs)-based NRR catalysts is very limited. In this paper, using FeN@(n, 0) CNTs (n = 3 ~ 10) as the representative catalysts, we demonstrate that the CNT curvatures will affect the spin polarization of the catalytic active centers, the activation of the adsorbed N molecules and the Gibbs free energy barriers for the formation of the critical intermediates in the NRR processes, thus changing the catalytic performance of CNT-based catalysts. Zigzag (8, 0) CNT was taken as the optimal substrate, and twenty transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Tc, Ru, Rh, Pd, W, Re, Ir, and Pt) were embedded into (8, 0) CNT via N group to construct the NRR catalysts. Their electrocatalytic performance for NRR were examined using DFT calculations, and TcN@(8, 0) CNT was screened out as the best candidate with a low onset potential of - 0.53 V via the distal mechanism, which is superior to the molecules- or graphene-support Tc catalysts. Further electronic properties analysis shows that the high NRR performance of TcN@(8, 0) CNT originates from the strong d-2π* interaction between the N molecule and Tc atom. TcN@(8, 0) CNT also exhibits higher selectivity for NRR than the competing hydrogen evolution reaction (HER) process. The present work not only provides a promising catalyst for NRR, but also open up opportunities for further exploring of low-dimensional carbon-based high efficiency electrochemical NRR catalysts.
基于碳的单原子催化剂（SACs）由于其可持续性、高效性和绿色优势，在电化学氮还原反应（NRR）中受到越来越多的关注。然而，目前基于碳纳米管（CNTs）的 NRR 催化剂的研究非常有限。在本文中，我们以 FeN@(n, 0)CNTs（n=3~10）为代表的催化剂为例，证明 CNT 的曲率会影响催化活性中心的自旋极化、吸附 N 分子的活化以及 NRR 过程中关键中间体形成的吉布斯自由能垒，从而改变 CNT 基催化剂的催化性能。我们选择锯齿型（8, 0）CNT 作为最佳衬底，通过 N 基团将二十种过渡金属原子（Sc、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Nb、Mo、Tc、Ru、Rh、Pd、W、Re、Ir 和 Pt）嵌入到（8, 0）CNT 中，构建了 NRR 催化剂。通过密度泛函理论（DFT）计算对它们的 NRR 电催化性能进行了测试，通过远程机制筛选出具有低起始电位-0.53 V 的 TcN@(8, 0)CNT 作为最佳候选物，优于分子或石墨烯支撑的 Tc 催化剂。进一步的电子性质分析表明，TcN@(8, 0)CNT 的高 NRR 性能源于 N 分子和 Tc 原子之间的强 d-2π*相互作用。与竞争的析氢反应（HER）过程相比，TcN@(8, 0)CNT 对 NRR 具有更高的选择性。本工作不仅为 NRR 提供了一种有前途的催化剂，也为进一步探索低维碳基高效电化学 NRR 催化剂开辟了机会。
