Fig. 5: DFT calculations of ORR activity and selectivity on different motifs.

a Pourbiax diagram for determining the steady state coverage of the oxygenated species on Pd3 under 2e- ORR standard redox potential (0.70 V). The inset shows the side view of the most stable coverage. Color code for the atomic structure; C: gray, O: red, Cyan: Pd. b Free energy diagram for 2e- ORR over the most stable structure from Pourbiax analysis at 0.70 V. c Optimized DFT model structures with nearby epoxy functional groups (highlighted by orange dashed circles) on the most stable O*/HO* covered Pd3 and Pd4 clusters. d Activity volcano plot, the y axis is the calculated limiting potential (UL), defined as the maximum potential at which the reaction steps become downhill in free energy. The x axis is the calculated free energy of HOO*. Horizontal dashed line is the standard redox potential for the 2e- ORR (0.70 V).