Directing electron flow via orbital-tailored heterojunctions toward selective H2O2 photosynthesis

Mo 4d-S 3p orbital hybridization effectively reshapes the electronic band structure. • Sulfur vacancies shift from recombination centers to efficient charge-transfer channels. • Mo S Ni bridging orbital channels establish a robust built-in electric field. • Mo–Ni orbital synergy enables a highly selective 2e⁻ oxygen reduction pathway. This work addresses the fundamental dilemma between charge separation efficiency and surface reaction selectivity in heterogeneous photocatalysis through synergistic orbital engineering. By introducing Mo dopants and sulfur vacancies (V S ) into Zn 3 In 2 S 6 , the localized electronic states of isolated V S are transformed into delocalized charge channels via strong Mo 4d-S 3p orbital hybridization. This orbital-level modulation effectively suppresses charge recombination while optimizing the band structure for visible-light absorption. Coupled with in-situ grown Ni 4 S 3 , an interfacial Mo-S-Ni orbital bridge is constructed, which not only establishes a robust built-in electric field to direct electron flow toward Ni 4 S 3 but also tailors the local coordination environment for selective two-electron oxygen reduction. The resulting heterojunction photocatalyst achieves an exceptional H 2 O 2 production rate of 163.0 ± 2.1 μM h −1 in pure water without any sacrificial agent. Notably, the H 2 O 2 production rate of 252.1 ± 2.4 μM h −1 is attained at a tetracycline hydrochloride (TC) concentration of 20 mg L −1 , 1.5 times higher than that in pure water. This study demonstrates that precise orbital coupling can integrate carrier dynamics management with reaction pathway control, providing a new design paradigm for noble metal-free, high-performance and multifunctional photocatalytic systems. Download: Download high-res image (216KB) Download: Download full-size image