First-principles study of the effect of the local coordination environment on the electrochemical activity of Pd1-CxNy single atom catalysts

Development of more efficient HER and ORR electrocatalysts is crucial for the production and utilization of H2 as a clean and sustainable energy carrier. M−N−Cs based single-metal-atom electrocatalysts have been extensively reported to be the alternatives to cost-ineffective Pt electrocatalysts, and their activities were significantly sensitive to the local coordination environment, but the underlying mechanism is still unclear yet. Herein, effects of the local coordination numbers and coordinated components of a single Pd atom in Pd1-NxCy on the HER and ORR activities were systematically investigated using theoretical calculations. We found that change in the local coordination environment is an effective way to modulate the electrochemical activities, and the four-atom-coordinated Pd1-N2C2-2 and the three-atom-coordinated Pd1-N3C0-3 were the most promising HER and ORR electrocatalysts, respectively. This work provides valuable insights into designing more efficient M−N−Cs electrocatalysts for HER and ORR, as well as the other important electrochemical processes.