High‐Performance Mesoporous Catalysts of Ultrasmall Hexagonal Thiospinel Nanocrystals for Visible‐Light Hydrogen Evolution

Abstract Semiconductor nanocrystals are at the frontier of energy conversion research owing to their tunable optoelectronic attributes and versatile surface activities. Here high‐surface‐area mesoporous frameworks comprising linked CdIn₂S₄ nanocrystals as efficient catalysts are presented for visible‐light‐driven hydrogen production. X‐ray total scattering analysis discloses hexagonally‐structured CdIn₂S₄ thiospinel nanoparticles forming the porous structure. Further analytic results indicate that these newly‐made ensembles possess an open‐up architecture that is highly conductive and susceptible to modification. Through appropriate selection of the synthesis conditions, it is demonstrated that the present synthetic protocol is general, allowing the preparation of porous materials from thiospinel nanoparticles with various sizes and compositions. This study shows that coupling of CdIn₂S₄ mesostructures and Ni₂P nanosheets substantially expedites the kinetics of water photo‐splitting by effectively reinforcing the separation of photogenerated carriers at the interfaces. Thus, mesoporous Ni₂P/CdIn₂S₄ heterojunctions instigate a remarkable improvement in the hydrogen generation rate (≈29.3 mmol h⁻¹ g_cat⁻¹), presenting an apparent quantum yield of 61.7% at 420 nm monochromatic light. A combination of electrochemical and spectroscopic studies unveils a pertinent mechanistic link between the charge‐transfer dynamics and intrinsic photochemical activity in these nanostructures.