Hollow semiconductor nanostructures with direct Z-scheme heterojunction have significant advantages for photocatalytic reactions, and optimizing the interfacial charge transmission of Z-scheme heterojunction is the hinge to achieve excellent solar conversion efficiency. In this work, tubular Ni_1−xCo_xS₂-CdS heterostructures with reinforced Z-scheme charge transmission were constructed through an In-metal-organic framework (MOF) templated strategy. The Z-scheme charge transfer mechanism was sufficiently confirmed by combining density functional theory (DFT) calculation, X-ray photoelectron spectroscopy (XPS), surface photovoltage spectroscopy (SPV), and radical testing results. Crucially, the use of sodium citrate complexant contributes to the formation of intimate heterointerface, and the Fermi level gap between CdS and NiS₂ is enlarged through Co doping into NiS₂, which enhances the built-in electric field and photo-carriers transmission driving force for Ni_1−xCo_xS₂-CdS heterojunction, resulting in an evidently promoted activity toward H₂ evolution reaction (HER). Under visible-light (λ > 400 nm) irradiation, the Ni_1−xCo_xS₂-CdS composite with 10 mol% Co doping and 80 wt.% CdS (NC_0.10S-80% CdS) achieved an outstanding HER rate up to 35.94 mmol·g⁻¹·h⁻¹ (corresponding to the apparent quantum efficiency of 34.7% at 420 nm), approximately 76.4 times that of 3 wt.% Pt-loaded CdS and it is much superior to that of most CdS-based photocatalysts ever reported. Moreover, the good photocatalytic durability of Ni_1−xCo_xS₂-CdS heterostructures was validated by cycling and long-term HER tests. This work could inspire the development of high-performance Z-scheme heterojunction via optimizing the morphology and interfacial charge transmission.

Photocatalytic water splitting for hydrogen (H₂) production is a green sustainable technology, in which highly-efficient steady photocatalysts are fundamentally required. In this work, unique CdS/Cd_0.5Zn_0.5S-Mo_1−xW_xS₂ photocatalyst constructed by CdS hollow nano-spheres with successively surface-modified Cd_0.5Zn_0.5S shell and defect-rich Mo_1−xW_xS₂ ultrathin nanosheets was reported for the first time. Interestingly, the Cd_0.5Zn_0.5S shell could greatly enhance the photo-stability and reduce the carrier recombination of CdS. Meanwhile, enriching active sites and accelerating charge transfer could be achieved via anchoring defect-rich Mo_1−xW_xS₂ onto CdS/Cd_0.5Zn_0.5S hollow heterostructures. Specifically, the optimized CdS/Cd_0.5Zn_0.5S-Mo_1−xW_xS₂ (6 h Cd_0.5Zn_0.5S-coating, 7 wt.% Mo_1−xW_xS₂, x = 0.5) hybrid delivered an exceptional H₂ generation rate of 215.99 mmol·g⁻¹·h⁻¹, which is approximately 502, 134, and 23 times that of pure CdS, CdS/Cd_0.5Zn_0.5S, and 3 wt.% Pt-loaded CdS/Cd_0.5Zn_0.5S, respectively. Remarkably, a high H₂ evolution reaction (HER) apparent quantum yield (AQY) of 64.81% was obtained under 420-nm irradiation. In addition, the CdS/Cd_0.5Zn_0.5S-Mo_1−xW_xS₂ was also durable for H₂ production under long-term irradiation. This work provides valuable inspirations to rational design and synthesis of efficient and stable hybrid photocatalysts for solar energy conversion.