Fig. 1: Synthesis and morphology of Co/Co3O4/CoB.

a Schematic diagram showing the synthesis process of Co/Co3O4/CoB. b AFM image of Co/Co3O4/CoB. The inset shows the height profile along the red line in (b). c HRTEM image of Co/Co3O4/CoB. d Aberration-corrected HAADF-STEM image of Co/Co3O4/CoB. e HAADF-STEM image and the corresponding EELS mappings of Co, O, and B elements in Co/Co3O4/CoB. Source data for Fig. 1 are provided as a Source Data file.