(a) Overpotential volcano projected on the ΔG OH description. Triangles denote the DFT-calculated overpotentials for single-site M–N–C catalysts, whereas circles represent those for dual-site M–N–C with curvature. Dashed and dotted lines highlight the apex of these overpotential volcanoes. (b) Timeline with outstanding, experimentally measured ORR and OER potentials for both platinum-group metals and metal–carbon–nitrogen (M–N–C) catalysts. The selected potentials correspond to a current ...