Ma Ziyu, Lv Peng, Wu Donghai, Li Xue, Chu Ke, Ma Dongwei, Jia Yu
Key Laboratory for Special Functional Materials of Ministry of Education, and School of Materials Science and Engineering, Henan University, Kaifeng475004, China.
Joint Center for Theoretical Physics, and Center for Topological Functional Materials, Henan University, Kaifeng475004, China.
Inorg Chem. 2022 Nov 7;61(44):17864-17872. doi: 10.1021/acs.inorgchem.2c03204. Epub 2022 Oct 26.
Efficient and low-cost electrocatalysts are urgently required for the electrocatalytic N reduction reaction (NRR) to produce valuable NH. Single-atom catalysts (SACs) represent one class of promising candidates. Besides the defects on the basal plane, very recently, the one-dimensional edge universally existing in the finite graphene or carbon sheet has gained attention as the anchoring site for SACs, which may enable unique catalytic mechanism. Herein, using first-principles calculations, we systematically investigated the NRR over SACs of transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Nb, Mo, and W) anchored by the N-modified edge of the graphene armchair nanoribbon (denoted as TM@GNR). Three criteria were employed to screen the best candidate from all the TM@GNR, including the high stability of TM@GNR, the preferable adsorption of N compared with H, and the lower applied potential for the first protonation of N compared with that of the active site. Accordingly, V(Nb)@GNR were theoretically demonstrated to be promising NRR electrocatalyst toward NH with low limiting potentials of -0.65 (-0.52) V, excellent selectivity of ∼100% (97%), and good stability. Particularly, NRR on the V@GNR and Nb@GNR precedes through a novel reaction mechanism with three spectator N molecules. Further analysis reveals that the strong capture and activation of N molecules by the edge-anchored V (Nb) atoms derives from their localized spin moment and atomic orbitals. Our studies emphasize the great potential of the edge of carbon materials to synthesize SACs for NRR and other reactions, and further reveal a novel NRR reaction mechanism on SACs.
电催化氮还原反应（NRR）制备有价值的NH₃迫切需要高效且低成本的电催化剂。单原子催化剂（SACs）是一类很有前景的候选材料。除了基面缺陷外，最近，有限石墨烯或碳片中普遍存在的一维边缘作为SACs的锚定位点受到关注，这可能会产生独特的催化机制。在此，我们采用第一性原理计算，系统研究了由石墨烯扶手椅纳米带的N修饰边缘锚定的过渡金属（Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Ru、Rh、Pd、Nb、Mo和W）的SACs上的NRR（表示为TM@GNR）。采用三个标准从所有TM@GNR中筛选出最佳候选材料，包括TM@GNR的高稳定性、与H相比对N的优先吸附以及与活性位点相比N首次质子化的较低应用电位。因此，理论上证明V（Nb）@GNR是有前景的NRR电催化剂，对NH₃的极限电位低至-0.65（-0.52）V，选择性优异，约为100%（97%），稳定性良好。特别是，V@GNR和Nb@GNR上的NRR通过一种与三个旁观N分子的新型反应机制进行。进一步分析表明，边缘锚定的V（Nb）原子对N分子的强捕获和活化源于其局域自旋矩和原子轨道。我们的研究强调了碳材料边缘在合成用于NRR和其他反应的SACs方面的巨大潜力，并进一步揭示了SACs上一种新型的NRR反应机制。
