Defective ZnIn2S4/NiO Z-scheme heterostructure for photothermal-assisted high performance photocatalytic hydrogen evolution under visible light

The photocatalytic hydrogen evolution reaction (HER) has received significant attention for its potential to efficiently harness renewable solar energy, producing green hydrogen fuel and oxygen as a by-product, thereby addressing the global energy crisis. However, bare photocatalysts such as ZnIn 2 S 4 often exhibit limited performance in water splitting due to their narrow light absorption spectrum, inadequate photoinduced charge carrier mobility, significant charge recombination, and sluggish surface kinetics. This study developed a novel two-dimensional (2D) ZnIn 2 S 4 /nickel vacancies-rich NiO (V Ni –NiO) heterostructured nanosheet (ZnIn 2 S 4 /V Ni –NiO) using a facile low-temperature reflow strategy. The resulting 2D ZnIn 2 S 4 /V Ni –NiO heterostructure demonstrated a high visible-light photocatalytic HER rate of 9.8 mmol g −1 h −1 and an apparent quantum efficiency of 5.68 % (λ = 420 nm), representing approximately a sevenfold improvement compared with pristine ZnIn 2 S 4 photocatalysts. The exceptional photothermal properties of V Ni –NiO continuously generate internal heat under visible light irradiation, increasing the local temperature of the photocatalyst and accelerating charge migration. Several synergistic mechanisms contribute to the enhanced performance. Firstly, the introduction of V Ni –NiO species effectively broadens the light response region to the visible light spectrum. Secondly, the Z-scheme heterojunction, with optimal band alignment at the ZnIn 2 S 4 /V Ni –NiO interface, creates an internal electric field that promotes carrier separation. Furthermore, the unique 2D nanosheets enriched with nickel vacancies provide numerous active sites, while the porous channels within the photocatalyst facilitate efficient physical transport and allow the generated gases to escape. This study presents a critical advancement in photocatalytic HER, that underscore the potential for scalable and efficient green hydrogen production, a viable solution to the global energy crisis. • Promising photothermal-assisted photocatalytic hydrogen evolution is revealed. • Nickel vacancies-rich NiO effectively expands activating spectrum of photocatalyst to visible light. • Synergies of heterostructured photocatalyst yields sevenfold improvement. • Novel photocatalyst material design strategy enables green hydrogen production.