Harnessing Lattice Strain for Charge Redistribution to Activate Mo-Doped ZnIn2S4 with Floatable Architecture toward Durable Photocatalytic Hydrogen Evolution

Developing floatable photocatalysts that simultaneously suppress photocorrosion and promote charge separation is highly desired for practical solar hydrogen production but remains challenging. Herein, a floatable Mo-doped ZnIn2S4 (Mo-ZIS) photocatalyst is demonstrated to achieve durable hydrogen evolution through lattice-strain-induced charge redistribution. Compressive strain, introduced by Mo4+ substitution at Zn2+ sites, induces local lattice distortion and strengthens Mo−S bonding. Comprehensive theoretical calculations and in situ spectroscopic analyses reveal that this strain drives a pronounced charge redistribution, specifically electron depletion on Mo and accumulation on adjacent S, which downshifts the S p-band center and elevates the sulfur vacancy formation energy to 2.68 eV, thereby fundamentally suppressing photocorrosion. Concurrently, an S-scheme heterojunction with Cu7S4 enables directional electron transfer and spatial charge separation. The three-layer floatable architecture creates a gas−liquid−solid three-phase interface that maximizes light utilization and facilitates H2 release. Consequently, the optimized photocatalyst achieves a hydrogen evolution rate of 301.22 mmol m−2 h−1 under visible light, which is 21 times that of pristine ZnIn2S4, and retains over 95% of its initial activity after 14 cycles. This work establishes a strain-modulated charge redistribution paradigm for durable sulfide-based photocatalysts and offers a promising route toward practical solar-to-hydrogen conversion.