NiSe ₂ /GDY/Sv‐CdZnS Dual S‐Scheme Heterojunction Boosts Full‐Spectrum Photocatalytic Hydrogen Evolution via Synergistic Ladder‐Like Built‐In Electric Field and Photothermal Effects

Abstract Single‐component photocatalysts often suffer from low solar utilization and rapid charge recombination. Constructing composite systems, particularly dual S‐scheme heterojunctions, offers a promising route to overcome these limitations. Accordingly, a ternary dual S‐scheme heterojunction photocatalyst (NS/GDY/Sv‐CZS), composed of sulfur‐vacancy‐engineered Cd _0.5 Zn _0.5 S nanorods jointly modified with graphdiyne (GDY) and NiSe ₂ (NS), is successfully synthesized via a simple ball‐milling and solvothermal methods. The integration of dual S‐scheme charge transfer, defect engineering, and photothermal effects enables efficient charge separation and accelerated surface reactions. A strong ladder‐like built‐in electric field at the interfaces drives directional electron migration from Sv‐CZS to GDY and NS, while GDY and NS function as dual photothermal components, converting solar energy into localized heat. This synergy significantly reduces the energy barrier for water splitting and enhances the photocatalytic hydrogen evolution performance. The composite system exhibits an outstanding photocatalytic hydrogen evolution rate, reaching 167.69 mmol·g ⁻¹ ·h ⁻¹ under simulated sunlight irradiation, which is 2.5 times higher than that of pure Sv‐CZS. Under visible‐light illumination, the hydrogen evolution rate reaches 109.67 mmol·g ⁻¹ ·h ⁻¹ . This work demonstrates that combining dual S‐scheme architecture with defect and photothermal engineering provides an effective strategy for boosting photocatalytic performance, offering valuable guidance for designing high‐efficiency photocatalysts for sustainable hydrogen production.