Robust visible-light photocatalytic H2 evolution on 2D RGO/Cd0.15Zn0.85In2S4–Ni2P hierarchitectures

Abstract

Photocatalytic water-splitting to produce hydrogen (H₂) is considered one of the most promising strategies to solve the increasing energy and environmental challenges facing humanity. However, the major obstacle is the lack of highly efficient photocatalysts with visible-light absorption capability and prominent charge transfer and separation. Herein, we developed for the first time an interface-engineered 2D hierarchitecture comprising ultrathin Cd-doped ZnIn₂S₄ (Cd_0.15Zn_0.85In₂S₄) nanosheets coupled with Ni₂P nanoparticles as a cocatalyst and reduced graphene oxide (RGO) nanosheets as an electron mediator. Under visible-light (λ > 400 nm) irradiation, the RGO/Cd_0.15Zn_0.85In₂S₄–Ni₂P composite displayed an enhanced H₂ evolution activity of 14.56 mmol h⁻¹ g⁻¹ that is 22 times that of pristine ZnIn₂S₄, and much higher than those of RGO/Cd_0.15Zn_0.85In₂S₄, Cd_0.15Zn_0.85In₂S₄–Ni₂P, Pt-loaded RGO/Cd_0.15Zn_0.85In₂S₄, and many previously reported ZnIn₂S₄-based photocatalysts. Additionally, the RGO/Cd_0.15Zn_0.85In₂S₄–Ni₂P hybrids showed outstanding long time cycling stability. The excellent photocatalytic HER capability of our photocatalyst could be attributed to the enhanced light-harvesting capability of porous hierarchitectures, increased charge transfer and separation via the interface-engineered Schottky heterojunctions, and the many active sites of the Ni₂P cocatalyst. The synergistic cooperation of the cocatalyst and electron mediator in 2D nanostructures offers a promising approach to prepare efficient solar photocatalysts.