Binary heteroatom dopants enable carbon-based heterostructures for efficient photoelectrocatalytic H2O2 synthesis in a wide pH range

[Display omitted] •N,S-CS/CN achieved the high H2O2 activity in acid, neutral and alkaline conditions.•The carbon-based heterostructures could effectively avoid the charge recombination.•The synergistic effect of S- and N-site was conducive to H2O2 production. Photoelectrocatalytic (PEC) H2O2 synthesis from water and oxygen is a prospective approach for the manufacture of solar fuels and value-added versatile chemicals. However, the development of the efficient photocathode remains a formidable challenge because of the inferior selectivity and yield of H2O2 derived from the multiple electron transfers affected by pH conditions. Herein, we report a metal-free carbon-based heterostructure material with N, S co-doping, where binary heteroatom-doped carbon sphere (N,S-CS) is loaded on carbon nitride (C3N4) polymer, achieving an efficient synthesis of H2O2 in a wide pH range. DFT calculations and experimental results uncover that S- and N-site can suppress the O-O cleavage and facilitate the *OOH formation through their subtle microenvironment, mediating the superior 2e- oxygen reduction selectivity to H2O2 in acids and alkalis, respectively. This work provides a cost-effective strategy for designing an efficient photocathode for H2O2 production in a wide pH environment.