Potential not only governs the direction of electrochemical reactions, but also shapes the electronic properties of single-atom catalysts dramatically. However, it is a challenge to simulate the effects of potential theoretically. Normally, DFT calculations are performed at a constant number of electrons, not a constant voltage. In this work, we apply a new fixed-potential method (grand canonical method) in the DFT simulation to mimic the electrochemical processes, in which the total number of the electron in the system was floated to match the ‘‘applied voltage,’, or the electrode Fermi energy at the atomic level. Here, the single-atom catalysts on two-dimension substrates for the oxygen evolution reaction process are used as examples to test the fixed-potential method. This fixed-potential method changes the rate-determining step and yields an overpotential difference of as much as 0.48 V in comparison with the conventional charge-neutral method. The quantitative error in the overpotential is not as important as the qualitative error in rate-determining steps. These errors can be avoided via the fixed-charge method with the proper charge. We believe our work advances the understanding of the effects of potential on the catalytic process in real electrochemical reactions and offers practical guidance for designing catalysts.

电势不仅决定着电化学反应的方向，而且还极大地影响了单原子催化剂的电子性能。但是，从理论上模拟电势的影响是一个挑战。通常，DFT计算是在恒定数量的电子而不是恒定电压下进行的。在这项工作中，我们在DFT模拟中应用了一种新的固定电位方法（大规范方法）来模拟电化学过程，其中系统中的电子总数浮动以匹配“施加电压”，或在原子级的电极费米能量。在此，以二维衬底上用于析氧反应过程的单原子催化剂为例，测试固定电位法。与传统的电荷中性方法相比，这种固定电位方法改变了速率确定步骤，并产生了高达0.48 V的过电位差。过电位中的定量误差不如速率确定步骤中的定性误差重要。通过采用适当充电的固定充电方法可以避免这些错误。我们相信，我们的工作将促进人们对实际电化学反应中电势对催化过程影响的理解，并为设计催化剂提供实用指导。通过采用适当充电的固定充电方法可以避免这些错误。我们相信，我们的工作将促进人们对实际电化学反应中电势对催化过程影响的理解，并为设计催化剂提供实用指导。通过采用适当充电的固定充电方法可以避免这些错误。我们相信，我们的工作将促进人们对实际电化学反应中电势对催化过程影响的理解，并为设计催化剂提供实用指导。