Customizing Transition Metal Chalcogenide Heterostructure Photosystems toward Multifarious Photoredox Catalysis.

Fine tuning of charge motion over homogeneous transient metal chalcogenides heterostructured photoanodes for photoelectrochemical water splitting

Benefiting from their excellent light-capturing ability, suitable energy band structure and abundant active sites, transition metal chalcogenides (TMCs) have been attracting widespread attention in heterogeneous photocatalysis. Nonetheless, TMCs still suffer from sluggish charge transfer kinetics, a rapid charge recombination rate and poor stability, rendering the construction of high-performance artificial photosystems challenging. Here, a ternary dumbbell-shaped CdS/MoS2/CuS heterostructure with spatially separated catalytically active sites has been elaborately designed. In such a heterostructured nanoarchitecture, MoS2 clusters, selectively grown on both ends of the CdS nanowires (NWs), act as terminal electron collectors, while CuS nanolayers, coated on the sidewalls of CdS NWs through ion exchange, form a P-N heterojunction with the CdS NW framework, which accelerates the migration of holes from CdS to CuS, effectively suppressing the oxidation of sulfide ions and improving the stability of CdS NWs. The well-defined dumbbell-shaped CdS/MoS2/CuS ternary heterostructure provides a structural basis for spatially precise regulation of the charge migration pathway, where photogenerated electrons and holes directionally migrate to the MoS2 and CuS catalytic sites, respectively, ultimately achieving efficient carrier separation and significantly enhancing photoactivity for both photocatalytic hydrogen generation and selective organic transformation under visible light. Moreover, we have also ascertained that such ion exchange and interface configuration engineering strategies are universal. Our work features a simple yet efficient strategy for smartly designing multi-component heterostructures to precisely modulate spatially vectorial charge separation at the nanoscale for solar-to-hydrogen conversion.

Finely tuning the charge transfer constitutes a central challenge in photocatalysis, yet exquisite control of the directional charge transfer to the target reactive sites is hindered by the rapid charge recombination. Herein, dual separated charge transport channels were fabricated in a one-dimensional transition-metal chalcogenide (TMC)-based system via an elaborate layer-by-layer (LbL) self-assembly approach, for which oppositely charged metal-ion-coordinated branched polyethylenimine (BPEI) and MoS2 quantum dots (QDs) were alternately integrated to fabricate the multilayered TMC@(BPEI/MoS2 QDs)n heterostructures with controllable interfaces. Photocatalytic hydrogen generation performances of such ternary heterostructures under visible light irradiation were evaluated, which unravels that the BPEI layer not only behaves as "molecule glue" to enable the electrostatic LbL assembly with MoS2 QDs in an alternate stacking fashion on the TMC frameworks but also acts as a unidirectional hole-transfer channel. More significantly, transition-metal ions (Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) coordinated on the outmost BPEI layer are able to function as interfacial electron transfer mediators for accelerating the interfacial cascade electron transport efficiency. These simultaneously constructed dual high-speed electron and hole-transfer channels are beneficial for boosting the charge separation and enhancing the photocatalytic hydrogen evolution performances.

Encapsulation of colloidal semiconductor quantum dots into metal-organic frameworks for enhanced antibacterial activity through interfacial electron transfer

Significantly activated persulfate by novel carbon quantum dots-modified N-BiOCl for complete degradation of bisphenol-A under visible light irradiation

Precise interface modulation cascade enables unidirectional charge transport

Steering bi-directional charge transfer via non-conjugated insulating polymer

Transition-metal chalcogenide quantum dots (TMCs QDs) exhibit emerging potential in the field of solar energy conversion due to large absorption coefficients for light harvesting, quantum size effect, and abundant active sites. However, fine-tuning the photoinduced charge carrier over TMCs QDs to manipulate the directional charge-transfer pathway remains challenging, considering their ultrashort charge lifetime and slow charge-transfer kinetics. To this end, herein, MoSx/PDDA/TMCs QDs heterostructures were exquisitely designed by a simple and green electrostatic self-assembly strategy under ambient conditions, wherein tailor-made negatively charged TMCs QDs stabilized by mercaptoacetic acid (MAA) were precisely self-assembled on the positively charged polydiallyl dimethylammonium chloride (PDDA)-modified MoSx nanoflowers (NFs), forming a well-defined three-dimensional heterostructured nanoarchitecture. As an electron trapping agent, an MoSx NFs cocatalyst benefits the unidirectional electron transfer from TMCs QDs to the ideal active centers on the MoSx NFs surface by tunneling the ultrathin insulating polymer interim layer, thereby boosting the charge separation efficiency and endowing self-assembled MoSx/PDDA/TMCs QDs heterostructures with considerably increased photocatalytic hydrogen evolution activity (1.96 mmol·g-1·h-1) and admirable stability under visible light irradiation. Our work will provide new insights into smart regulation of directional charge transfer over TMCs QDs-based photosystems for solar energy conversion.

Enhanced photocatalytic activity of ternary Ag3PO4/GO/g-C3N4 photocatalysts for Rhodamine B degradation under visible light radiation

Three-dimensional crosslinked structure assembled by novel elemental iodine doped Nb2O5 ultrathin nanosheets for exceptional visible-light photocatalytic performance

Nitrogen self-doped g-C3N4 nanosheets with tunable band structures for enhanced photocatalytic tetracycline degradation

Temperature-responsive polymer-tethered Zr-porphyrin MOFs encapsulated carbon dot nanohybrids with boosted visible-light photodegradation for organic contaminants in water

Pharmaceuticals, newly recognized classes of environmental pollutants, are becoming increasingly problematic contaminants of either surface water or ground water around industrial and residential communities. Pharmaceuticals are constantly released into aquatic environments, mainly due to their widespread consumption and complicated removal in wastewater treatment plants. Heterogeneous photocatalysis appear to be one of the most destructive advanced oxidation processes (AOPs) for organic contaminants and are possible to obtain complete mineralization of organic pollutants into eco-friendly end products under visible and solar light irradiation. In this study, flower-like In2S3 hierarchical nanostructures were successfully prepared via a facile solution-phase route, using thioacetamide as both sulfur source and capping agent. X-ray diffractometry (XRD) of the flowers revealed that the cubic structure of In2S3; morphological studies examined by scanning electron microscopy (SEM) showed the synthesized In2S3 nanostructure was flower-like hierarchitecture assembled from nanoscale flakes. X-ray photoelectron spectroscopy (XPS) analysis confirmed the stoichiometry of In2S3 nanoflowers. Furthermore, the photocatalytic activity studies revealed that the prepared indium(III) sulfide(In2S3) nanoflowers exhibit an excellent photocatalytic performance, degrading rapidly the aqueous pharmaceutical solution of Lisinopril under visible light irradiation. These results suggest that In2S3 nanoflowers will be a promising candidate of photocatalyst working in thevisible light range.

Ag2S nanoparticle promoted charge separation and transfer in g-C3N4 nanosheets for efficient photo and electro chemical performance

The burgeoning field of conjugated microporous polymers (CMPs) has generated widespread interest due to their potential as photocatalysts for hydrogen production from water. Nevertheless, their photocatalytic performance is sometimes hindered by inadequate charge separation and transfer, coupled with rapid charge recombination. Herein, a strategy to enhance photocatalytic performance via the customization of π‐bridges through the modulation of heteroatoms in a series of donor‐π‐acceptor (D‐π‐A) CMPs is proposed. This affords optimized energy levels and improved charge separation and transfer, thus boosting photocatalytic efficiency. Among various heteroatom substitutions, S‐doped CMP (10 mg) demonstrates the highest photocatalytic hydrogen evolution rate of 203 µmol h−1 (AQY450nm = 7.4%) under visible light irradiation. Subsequent experimental analysis reveals its superior photocatalytic performance can be largely related to its minimized exciton binding energy, facilitated charge transfer efficiency, and impeded charge recombination among these heteroatom‐doped D‐π‐A CMPs. This research paves the way for the rational design and modification of organic semiconductors for advanced solar‐driven photocatalysis by promoting charge separation and transfer.