Efficient and stable n-type sulfide overall water splitting with separated hydrogen production.

Luo, Haolin; Liu, Zhixi; Lv, Haifeng; Vequizo, Junie Jhon M; Zheng, Mengting; Han, Feng; Ye, Zhen; Yamakata, Akira et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

N-type sulfide semiconductors are promising photocatalysts due to their broad visible-light absorption, facile synthesis and chemical diversity. However, photocorrosion and limited electron transport in one-step excitation and solid-state Z-scheme systems hinder efficient overall water splitting. Liquid-phase Z-schemes offer a viable alternative, but sluggish mediator kinetics and interfacial side reactions impede their construction. Here we report a stable Z-scheme system integrating n-type CdS and BiVO₄ with a [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ mediator, achieving 10.2% apparent quantum yield at 450 nm with stoichiometric H₂/O₂ evolution. High activity reflects synergies between Pt@CrO<sub>x</sub> and Co<sub>3</sub>O<sub>4</sub> cocatalysts on CdS, and cobalt-directed facet asymmetry in BiVO₄, resulting in matched kinetics for hydrogen and oxygen evolution in a reversible mediator solution. Stability is dramatically improved through coating CdS and BiVO<sub>4</sub> with different oxides to inhibit Fe<sub>4</sub>[Fe(CN)<sub>6</sub>]<sub>3</sub> precipitation and deactivation by a hitherto unrecognized mechanism. Separate hydrogen and oxygen production is also demonstrated in a two-compartment reactor under visible light and ambient conditions. This work unlocks the long-sought potential of n-type sulfides for efficient, durable and safe solar-driven hydrogen production.