突破电催化合成氨过程中吸附能之间线性依赖关系的理论研究

Electrochemical synthesis of ammonia is one of the most important means in artificial nitrogen fixation under mild conditions. To improve the performance of the electrocatalysts, one needs to increase the adsorption energies of N2 and N2H, and at the same time, weaken the adsorption of NH2. However, due to the intrinsic linear scaling relationship between adsorption energies, these values for N2, N2H, and NH2 tend to change in the same direction, and cannot be tuned independently. In this project, we are dedicated to exploring an effective way to break the linear correlation of adsorption energies in electrochemical nitrogen fixation, by using first-principles simulations. We focus on the adsorption energy of key adsorbates, such as N2, N2H, and NH2, on various metal alloy surfaces as well as interfaces composed of the surfaces and two-dimensional materials. Three strategies, i.e., binary metal alloying, confinement effect in real space, and dual adsorption sites, will be synergistically employed in breaking the linear scaling relations. Based on such exploration, interfacial catalytic systems, which are expected to exhibit excellent performance in electrocatalytic ammonia synthesis, will be designed, and their catalytic properties in the electrochemical environment will be investigated through theoretical simulations. This project will help to improve the electrocatalysts in electrochemical nitrogen fixation and will provide key guidelines for further experiments.

电化学合成氨是温和条件下人工固氮的重要手段之一。为提升该过程中电催化剂的性能，需要在增加N2和N2H吸附能的同时削弱NH2基团的吸附。然而，由于吸附能之间固有的线性相关关系的制约，N2、N2H及NH2的吸附能往往以相同的趋势发生变化而无法被独立地调节。本项目通过第一性原理的理论模拟，探索能够打破电化学固氮成氨反应中线性相关关系的有效途径。我们的研究着眼于N2、N2H及NH2等关键吸附物在金属合金表面、以及表面与二维材料所构成的界面体系的吸附性质，力图以“二元合金化”、“空间限域效应”及“双吸附位点”三种策略的协同配合实现对线性相关关系的突破。基于这一突破，我们将设计有望在电化学合成氨中展现优异催化性能的界面催化体系，并通过电化学环境下的理论模拟揭示该体系的催化效果。本项目的开展将为电化学固氮成氨催化剂的性能提升提供重要的理论指导。

电化学合成氨是温和条件下人工固氮的重要手段之一。为提升该过程中电催化剂的性能，需要在增加N2和N2H吸附能的同时削弱NH2基团的吸附，这就需要突破吸附能之间固有的线性依赖关系。本项目通过基于第一性原理的计算模拟，探讨了若干调控策略 - 尤其是空间限域效应 - 在突破吸附能之间线性相关关系中的表现，并将这些策略运用于电化学固氮成氨反应中。研究发现了一些能够有效降低该反应过电位的外部调控手段，尤其是，通过施加适当程度的拉伸应力，或通过两种二维材料的结合以构建限域空间，都能使氮还原反应的过电位表现出显著的降低，而这确实都来源于对吸附能之间线性相关关系的突破。此外，作为氮气分子的等电子体，本项目还研究了乙炔分子及其加氢反应中间体在限域空间内的吸附及反应势能面，并分别从静态和动态两个视角探讨了空间限域效应对吸附能及线性相关关系的影响。本项目的研究对于提升氨合成电催化剂的性能具有一定的指导意义，在提升乙炔加氢反应催化剂的选择性方面也提出了新的思路。