An inter-atomic synergistic Co–Zn diatomic catalyst for efficient H2O2 electrosynthesis in neutral and alkaline media†

Abstract

The electrosynthesis of H₂O₂via the two-electron oxygen reduction reaction (2e⁻-ORR) is a promising alternative method due to its cost-effectiveness and environmentally friendly nature. Atomically dispersed Co single atoms are considered as the active catalyst for the 2e⁻-ORR, but they still suffer from the strong adsorption of the intermediate *OOH resulting in low selectivity for H₂O₂. Herein, we propose an inter-atomic synergistic strategy by constructing a heteronuclear diatomic catalyst (Co/ZnPc-S-C₃N₄) to optimize the adsorption of *OOH and enhance the performance of H₂O₂ electrosynthesis. In Co/ZnPc-S-C₃N₄, synthesized by a supramolecular strategy through π–π stacking between MPc (M = Co or Zn) and a S-doped C₃N₄ substrate, the incorporation of Zn induces electron transfer from cobalt to zinc constructing an electron-deficient cobalt center, which inhibits the cleavage of the O–O bond in adsorbed *OOH and favors the two-electron ORR pathway. Thus, Co/ZnPc-S-C₃N₄ exhibits more than 95% H₂O₂ selectivity and nearly 100% Faraday efficiency as well as long-term stability in both alkaline and neutral electrolytes, with H₂O₂ yields of 5.35 and 5.45 mol g_cat⁻¹ h⁻¹, respectively, outperforming the reported analogous catalysts. This work provides an effective strategy for the design of heteronuclear diatomic catalysts, making them promising candidates for the 2e⁻-ORR.