College of Chemistry and Chemical Engineering, Key Laboratory of Photonic and Electronic Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin, 150025, China.
Phys Chem Chem Phys. 2018 May 9;20(18):12835-12844. doi: 10.1039/c8cp01215f.
The nitrogen reduction reaction (NRR) under ambient conditions using renewable energy is a green and sustainable strategy for the synthesis of NH3, which is one of the most important chemicals and carbon-free carriers. Thus, the search for low-cost, highly efficient, and stable NRR electrocatalysts is critical to achieve this goal. Herein, using comprehensive density functional theory (DFT) computations, we design a new class of NRR electrocatalysts based on a single transition metal (TM) atom supported on the experimentally feasible two-dimensional C2N monolayer (TM@C2N). Based on the computed free energies of each elementary pathway, Mo@C2N is predicted to exhibit the best catalytic activity among the TM@C2N, in which the proton-coupled electron transfer of the NH2* species to NH3(g) is the potential-determining step. Especially, the computed onset potential of the NRR on Mo@C2N is -0.17 V, which is even lower than that for the well-established stepped Ru(0001) surface (-0.43 V). Furthermore, the NRR catalytic performance of these TM@C2N can be well explained by their adsorption strength with N2H* species. Our findings open a new avenue for optimizing the TM catalytic performance for the NRR with the lowest number of metal atoms on porous low-dimensional materials.
在环境条件下使用可再生能源进行氮还原反应（NRR）是合成氨的一种绿色可持续策略，氨是最重要的化学品和无碳载体之一。因此，寻找低成本、高效和稳定的 NRR 电催化剂对于实现这一目标至关重要。在此，我们通过综合密度泛函理论（DFT）计算，设计了一类基于实验可行的二维 C2N 单层上负载单个过渡金属（TM）原子的新型 NRR 电催化剂（TM@C2N）。基于计算得到的各基元反应的自由能，预测 Mo@C2N 在 TM@C2N 中表现出最佳的催化活性，其中 NH2物种向 NH3(g)的质子耦合电子转移是决速步骤。特别地，Mo@C2N 上 NRR 的计算起始电位为-0.17 V，甚至低于公认的阶梯状 Ru(0001)表面（-0.43 V）。此外，这些 TM@C2N 的 NRR 催化性能可以通过它们与 N2H物种的吸附强度很好地解释。我们的发现为在多孔低维材料上用最少数量的金属原子优化 TM 对 NRR 的催化性能开辟了新途径。
