fig4

Figure 4. (A) The preparation process for Zn/CoN-C. Reproduced with permission from Ref.^[79]. Copyright 2019, Wiley-VCH; (B) Scheme of the synthesis process of NiCo DASs/N-C. Reproduced with permission from Ref.^[81]. Copyright 2022, Wiley-VCH; (C) Macrocyclic precursor-mediated encapsulation-pyrolysis to prepare DACs; (D) AC HAADF-STEM image of FeCu-DAC and the scale bar is 2 nm; (E) EELS of a FeCu dual atoms as labeled in the red rectangle in Figure 4D; (F) TOF-SIMS spectra of FeCu-DAC and Fe/Cu-SAC; (C-F) Reproduced with permission from Ref.^[87]. Copyright 2023, American Chemical Society. DACs: Dual-atom catalysts; AC HAADF-STEM: aberration-corrected high-angle annular dark-field scanning transmission electron microscopy; TOF-SIMS: time-of-flight secondary ion mass spectrometry.