An in situ grown ZnIn2S4 on Zn2SiO4:Ga3+ core–shell heterojunction for photocatalytic hydrogen production

Abstract

The creation of efficient photocatalysts for hydrogen production is a key strategy in tackling the fossil energy crisis. ZnIn₂S₄ shows potential as a photocatalyst, yet its practical use in photocatalysis is hindered by the swift recombination of electron–hole pairs. Herein, we constructed a core–shell heterojunction composite, Zn₂SiO₄:Ga³⁺@ZnIn₂S₄, via the in situ growth of ZnIn₂S₄ on the surface of Zn₂SiO₄:Ga³⁺persistent luminescent nanoparticles (PLNPs). The photocatalytic hydrogen evolution using the Zn₂SiO₄:Ga³⁺@ZnIn₂S₄ composite is significantly enhanced to 15.954 mmol g⁻¹ h⁻¹, which is 2 times higher than that of ZnIn₂S₄. This phenomenon can be traced back to the creation of a heterojunction between ZnIn₂S₄ and Zn₂SiO₄:Ga³⁺, coupled with the deep trap states typical of long-lasting afterglow materials. These factors work in tandem to enhance the separation of photogenerated electrons and holes within the photocatalyst, boosting its overall efficiency. Density functional theory calculations demonstrated that the Zn₂SiO₄:Ga³⁺@ZnIn₂S₄ heterojunction exhibits a remarkable synergistic effect, which not only boosts electron transfer efficiency at the interface but also fine-tunes the adsorption energies of hydrogen atoms. This interplay between the components creates a dynamic system that optimizes performance at the molecular level. The integration of PLNPs with ZnIn₂S₄ is anticipated to inspire new approaches for the design of PLNP-based round-the-clock photocatalysts, thereby offering improved solutions for the efficient decomposition of water for hydrogen production.