Fig. 3: ECL of Au₂₀-AC and Au₂₀(TBBT)₁₆ under potential step and scanning conditions and calculated stability of different valence states of Au₂₀-AC and Au₂₀(TBBT)₁₆ radical.

a Potential step self-annihilation ECL of Au₂₀-AC and Au₂₀(TBBT)₁₆. The concentration of nanocluster is 0.015 mM in Tol/ACN (1:1) with 0.1 M TBAP electrolyte. The potential was set between −1.6 and 1.1 V and stepped cyclically, each potential was held for 5 s, and no potential was applied in the first and final 5 s. Pt mesh was used as working electrode, Pt foil and SCE were used as counter and reference electrode, respectively. b Self-annihilation ECL-voltage curves from −1.6 V to 1.1 V of Au₂₀-AC and Au₂₀(TBBT)₁₆ in solution state. Initial scan to negative potential direction. The 3^rd cycle data was shown. c, d Theoretical calculation of structures of different valence states of Au₂₀-AC and Au₂₀(TBBT)₁₆ radical. The corresponding bond length is shown in Supplementary Table 2.