To rationally design electrocatalysts with high promising performance is essential for the nitrogen reduction reaction (NRR). Using the first principle density functional theory and ab initio molecular dynamic calculations, we systematically explored the activity, selectivity, and thermodynamic stability of the single-atom or tetra-nuclear metal clusters of Fe and Ru supported on Nb 2 C MXene modified by oxygen (fluorine) functional groups, resulting in one excellent electrocatalyst (labeling as Ru/Nb 2 CO 2 ) for NRR. The obtained Ru/Nb 2 CO 2 catalyst mainly undergoes electroreduction of nitrogen that proceeds via an enzymatic hybrid mechanism due to high selectivity (99.9%) and low ΔG PDS (ΔG PDS = 0.59 eV), and the catalyst also has superior stability at 500 K, suggesting Ru/Nb 2 CO 2 has high promising performance for electrocatalytic synthesis of ammonia.

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The design of high-performance single-atom catalysts (SACs) for two-electron oxygen reduction reaction (2e– ORR) is of great importance for the large-scale commercial application of H2O2 electrosynthesis. Herein, utilizing the combination of density functional theory (DFT) calculation and ab initio molecular dynamic (AIMD) simulation, an effective computational framework was built to identify the critical role of coordination fields and hydrosolvents in the 2e– ORR catalytic properties of SAC-based two substrates [pristine γ-type graphyne (γ-GY) and B-doped γ-GY]. The screening calculations of 168 TM@(B-doped) γ-GY (TM = transition metal) revealed that both Co@B1-2-γ-GY and Pd@B3-2-γ-GY feature outstanding catalytic properties with low overpotentials (0.06, 0.02 V) and excellent stability. The electronic structure results uncovered that viewing from the coordination field, electron-deficient boron atoms can manipulate the electron back-donation effect (d → π2p *) of the TM–O bond to mediate the H2O2 property. Solvent effect calculations revealed that the hydrogen-bond (H-bond) framework plays an important role in the high selectivity of H2O2 by facilitating the H transfer from water (>99.9 and 98.6% for Co@B1-2-γ-GY and Pd@B3-2-γ-GY), shedding light on the higher accuracy of an explicit solvent than that of an implicit one. This work will provide one way to better design high-selectivity SACs for H2O2 synthesis effectively.

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