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 gcat−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.

Efficient Visible Light Photocatalytic Hydrogen Evolution by Boosting the Interfacial Electron Transfer in Mesoporous Mott–Schottky Heterojunctions of Co2P-Modified CdIn2S4 Nanocrystals

“…Further evidence that the constituent nanocrystals do adopt a hexagonal crystal structure is shown in the high-resolution TEM (HRTEM) image. The distinct lattice fringes with an interplanar distance of 3.3 Å in Figure e are assigned to the (011) crystal planes of hexagonal CdIn 2 S 4 (space group P 6 3 mc ) . The different orientation of the lattice planes suggests the polycrystalline nature of CIS.…”

“…The crystal structures of mesoporous CIS and CP/CIS NCFs were verified via X-ray diffraction (XRD) analysis. The CIS NCFs exhibited three broad diffraction peaks at 2θ scattering angles from 20 to 60° (Figure a), which, according to previous investigations, belong to the hexagonal phase of CdIn 2 S 4 . The presence of broad diffraction peaks suggests that the materials are nanocrystalline in nature.…”

“…The CIS NCFs exhibited three broad diffraction peaks at 2θ scattering angles from 20 to 60° ( Figure 1 a), which, according to previous investigations, belong to the hexagonal phase of CdIn 2 S 4 . 19 The presence of broad diffraction peaks suggests that the materials are nanocrystalline in nature. The mesoporous CP/CIS NCFs with Co 2 P content up to 10 wt % displayed a similar XRD pattern with the pristine CIS with no detectable Co 2 P crystallites due to the small grain size and low content of Co 2 P. The high Co 2 P-loaded sample (15 wt %), however, apart from the XRD peaks belonging to CIS, showed an additional diffraction peak at 2θ ∼ 40.7°, which can be indexed to the (112) lattice planes of orthorhombic Co 2 P, confirming the formation of the Co 2 P/CIS heterostructure.…”

“…Recently, we devised a facile synthetic route to assemble mesoporous structures of hexagonal CdIn 2 S 4 nanocrystals (NCs) using colloidal chemistry and polymer-assisted self-assembly methods . Unlike the conventional high-temperature solid-state and solvothermal methods, − this synthetic approach enables us to fabricate nanostructured materials with large internal surface area, controllable grain composition, and high photocatalytic reactivity.…”

“…Recently, we devised a facile synthetic route to assemble mesoporous structures of hexagonal CdIn 2 S 4 nanocrystals (NCs) using colloidal chemistry and polymer-assisted self-assembly methods. 19 Unlike the conventional high-temperature solid-state and solvothermal methods, 20 − 22 this synthetic approach enables us to fabricate nanostructured materials with large internal surface area, controllable grain composition, and high photocatalytic reactivity. Herein, we couple polymer-templating self-assembly synthesis and a wet-chemical deposition method to produce new high-surface-area mesoporous semiconducting CdIn 2 S 4 frameworks decorated with highly dispersed metallic Co 2 P nanoparticles for efficient photocatalytic hydrogen evolution.…”