Fig. 1: Schematic illustration and morphology characterizations.

a Schematic illustration of the synthetic process for Co-M1-S-Se and Co-M1-M2-S-Se nanosheets at the oil/water interface. b, c TEM image for the Co-Ni-S-Se. d XRD of Co-Ni-S-Se, Ni-Ru-S-Se, Co-Ru-S-Se, standard NiCo2S4 card (PDF#20–0782). e HRTEM spectrum of Co-Ni-S-Se. f, g FFT and IFFT pattern of Co-Ni-S-Se. h–l HAADF-STEM spectrum with elemental mapping images for Co, Ni, S, and Se.