Facile defect engineering in ZnIn₂S₄ nanosheets for enhanced NIR-driven H₂ evolution

Near-infrared (NIR) light-driven water splitting to produce hydrogen (H₂) has long been of great interest in photocatalysis, but it remains a formidable challenge so far due to both kinetic and thermodynamic shortcomings. To break through this limitation, we demonstrate a noble metal-free two-dimensional ZnIn₂S₄-based photocatalyst rich in sulfur vacancies via a facile hydrothermal method and firstly realized NIR-driven H₂ production beyond 800 nm using single component ZnIn₂S₄-based materials. We disclosed the existence of an efficient Urbach tail transition to absorb long-wavelength NIR light according to the valence-band spectra, ultraviolet-visible-NIR diffuse reflectance spectra, steady-state photoluminescence spectra, transient photocurrent response, and electron paramagnetic resonance measurements. The successful construction of sulfur vacancies in ZnIn₂S₄ nanosheets not only extends the spectral absorption range but also has an excellent carrier diffusion property as well as an abundance of active sites. Therefore, our findings may provide an effective and promising perspective for the future development of NIR-responsive ZnIn₂S₄-based photocatalysts for highly efficient H₂ production.