Fig. 6: Comparison of the (NiCo)O_xS_1.33-x surface and the pure (NiCo)O_1.33 surface.

a iR-corrected LSV at a scan rate of 5 mV s⁻¹ of (NiCo)S_1.33 and (NiCo)O_1.33. b iR-corrected LSV of (NiCo)S_1.33 and (NiCo)O_1.33 before and after five CV cycles at a scan rate of 5 mV s⁻¹. c In-situ atomic HAADF images of (NiCo)S_1.33 after constantly applying different potentials for twenty seconds. d In-situ EELS spectra of O K-edge under different applied potential. The I, II and III peaks can be assigned to the hybridisation of O 2p with Co 3d, Ni 3d and Co 4sp orbitals, respectively. e, f Peak position of Co and Ni L₃-edge collected from the EELS spectra of (NiCo)S_1.33 and (NiCo)O_1.33 L-edge. g, h Signal strength variation diagram of characteristic Raman peaks of M-OH, Co-OOH and Ni-OOH of (NiCo)S_1.33 and (NiCo)O_1.33.