Synergy of amino and mercury(II) ions enables metallated graphyne with controlled charge migration for dual H₂O₂ photoproduction in pure water

Visible-light-driven overall hydrogen peroxide (H₂O₂) photosynthesis is a promising strategy for sustainable production of H₂O₂. However, it is still limited to the design of robust photocatalysts with controlled charge transfer both in photogenerated carrier relaxation and charge separation processes to achieve efficient dual-channel H₂O₂ photogeneration. Herein, a novel photocatalyst of aminated mercurated graphyne (NH₂-Hg-GY) is designed which achieves an overall visible light-driven co-catalyst-free photogeneration of H₂O₂ with a yield of 2112.6 μmol h⁻¹ g⁻¹ in a saturated O₂ atmosphere. Experimental and theoretical analysis revealed that NH₂-Hg-GY can effectively promote the absorbance of photons and generate long-lived photoinduced charges, which are eventually transferred to the surface defect states through a dual-channel carrier migration process and achieve a dual-channel pathway for H₂O₂ photogeneration integrating the two-electron oxygen reduction reaction on the benzene ring and the two-hole water oxidation reaction on the alkynyl group in NH₂-Hg-GY. Particularly, the synergy of the sp^x-p_π conjugation between the amino group and benzene and the d_π-p_π conjugation between Hg(II) ion and ethynyl unit within NH₂-Hg-GY alters the electronic structures of mercurated graphyne, which realize controllable carrier migration and efficient charge separation, thus achieving a superior overall H₂O₂ photogeneration.