Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China.

Macao Institute of Materials Science and Engineering, Macau University of Science and Technology, Taipa, Macau SAR 999078, China.

DFT calculations are performed at constant charge, while practical electrochemical reactions often take place under constant potential. To unravel the effect of the model difference on single-atom electrocatalysis, we implement benchmarked DFT and grand-canonical DFT calculations to systematically investigate the hydrogen adsorption on 99 single-atom M–N _x C _y motifs. We find that the initial electrode potentials for all M–N _x C _y are negative, leading to the loss of system electrons once their electrode potentials are fixed at 0 V/SHE. We prove that the quantitive difference of Δ G (*H) between the CCM and CPM is proportional to the square difference of total charge change before and after H adsorption, which originates from the adjustment of electronic occupation states. Our work provides theoretical insight into the differential capacitance model in the graphene-confining SACs for the HER and emphasizes the importance of CPM for in silico design of electrocatalysts. 中文翻译： DFT 计算是在恒定电荷下进行的，而实际的电化学反应通常在恒定电位下进行。为了揭示模型差异对单原子电催化的影响，我们实施了基准 DFT 和大规范 DFT 计算，以系统地研究 99 个单原子 M-N _x C _y 基序上的氢吸附。我们发现所有 M-N _x C _y 的初始电极电位都是负的，一旦它们的电极电位固定在 0 V/SHE，就会导致系统电子的损失。我们证明了 Δ G的数量差异 CCM 和 CPM 之间的 (*H) 与 H 吸附前后总电荷变化的平方差成正比，这源于电子占据状态的调整。我们的工作为 HER 的石墨烯限制 SAC 中的微分电容模型提供了理论见解，并强调了 CPM 在电子 催化剂设计中的重要性。