Hierarchical core-shell heterostructures of ZnIn2S4 nanosheets on electrospun In2O3 nanofibers with highly enhanced photocatalytic activity

Z-Scheme Ag2S-Ag-In2O3 Heterostructure with Efficient Antibiotics Removal under Natural Sunlight

The widespread distribution of antibiotics in natural waters is a great threat to human health. Photocatalytic degradation is an environmentally friendly technology to remediate antibiotic-polluted waters, driven by endless solar energy. Herein, a Z-scheme Ag2S-Ag-In2O3 heterostructure photocatalyst is prepared to remove antibiotics under environmental conditions. Under natural sunlight (light intensity: ∼78 mW/cm2) irradiation, the optimal Ag2S-Ag-In2O3 (10-ASAIO) exhibits considerable performance for decomposing diverse antibiotics, including norfloxacin (NOR), tetracycline hydrochloride, sulfisoxazole, ciprofloxacin, chlortetracycline hydrochloride, and ofloxacin. The NOR photodegradation rate constant of 10-ASAIO reaches 0.025 min-1, which is 12.50, 5.00, and 6.25 times higher than that of In2O3 (0.002 min-1), Ag-In2O3 (0.005 min-1), and Ag2S-In2O3 (0.004 min-1), respectively. This performance of the 10-ASAIO photocatalyst for decomposing NOR under natural sunlight exceeds most of the previously reported photocatalysts under a xenon lamp. Particularly, due to the intermittency of natural sunlight, a light-emitting diode (LED) lamp (light intensity: 5.1 mW/cm2) is also used as a light source, and 72.20% of NOR can be degraded with irradiation for 12 h. The effects of many water characteristics (water bodies, coexisting inorganic anions, pH, and humic acid) on the degradation performance of 10-ASAIO have been investigated, which exhibits stable degradation efficiency in variable aquatic environments. A 10-ASAIO catalyst-coated frosted glass sheet is fabricated to settle the problem of recovery of powder photocatalysts, and the immobilized catalyst shows outstanding activity and stability to decompose NOR. The photocatalytic mechanism and pathway of degrading NOR over 10-ASAIO have also been systemically investigated and proposed. The ecotoxicity (phytotoxicity and biotoxicity) of the 10-ASAIO photocatalyst and treated NOR solution have been tested by their toxic effects on cabbage seeds and Staphylococcus aureus (S. aureus). This work provides a feasible photocatalytic system for environmental pollutant remediation under natural sunlight or an LED lamp.

Boosting hydrogen evolution performance of nanofiber membrane-based composite photocatalysts with multifunctional carbon dots

Recent progress in the co-spinning of nanofibers and semiconductor particles offers a promising strategy for the development of photocatalytic devices, solving aggregation and catalyst recovery challenges. However, composite photocatalysts based on nanofiber membranes often suffer from poor conductivity, low hydrophilicity, and easy recombination of photogenerated electron-hole pairs in the semiconductor components. Here, to tackle the aforementioned issues of ZnIn2S4/polyacrylonitrile (ZIS/PAN) nanofiber-based catalysts, we prepared a composite carbon dots/ZnIn2S4/polyacrylonitrile (CZP) nanofiber membrane by blending carbon dots (CDs) with ZIS/PAN using the electrospinning process. The hydrogen evolution performance of the CZP photocatalyst was significantly improved by CDs, which enhanced the hydrophilicity, increased the light absorption, facilitated the transfer of photogenerated electrons, and reduced the recombination of photogenerated electron-hole pairs. Notably, the optimal CZP photocatalyst achieved a hydrogen evolution rate of 2250 μmol g-1h-1, which is about 23 % higher than that of the nanofiber membrane without CDs and 4.55 times higher than that of ZIS particles. The present work successfully improved the CZP nanofiber membrane of photocatalytic hydrogen evolution performance, and the membrane may benefit further device development by eliminating the need for stirring and simplifying the recovery process.

Local polarization redistribution in ZnmIn2S3+m for the enhancing synergetic piezo-photocatalytic overall water splitting

Piezo-photocatalytic water (deuterium oxide) decomposition is a promising strategy for realizing renewable energy, but the manipulation of the polar center remains a big challenge. This study uses a simple low-temperature hydrothermal process to successfully manufacture ZnmIn2Sm+3 (m = 1-3) (ZnIn2S4, Zn2In2S5 and Zn3In2S6). Incorporating both experimental and theoretical analyses, the structural contraction and local polarization of the Zn-S bond in Zn2In2S5 enhance the piezoelectric response and surface charge accumulation, which facilitate charge transfer and reduce the activation energy of water. Remarkably, Zn2In2S5 exhibits excellent piezoelectric photocatalytic total water splitting performance (H2/O2: 4284.72/1967.00 μmol g-1h-1), which is 1.77 times that of photocatalytic performance. Moreover, a significant enhancement in D2O splitting performance can be obtained for the optimized Zn2In2S5. Our work offers valuable insights into the disclosure of local polarization in catalysts for enhancing piezo-photocatalytic overall water splitting.

ZnIn2S4 Nanosheets for Efficient NO2 Detection at Room Temperature: Insights into the Role of Sulfur Vacancies

Engineering atomic vacancies in metal sulfide semiconductors allows for the efficient tuning of their electronic and chemical properties. In this work, we synthesized hollow tubular structures constructed by bimetallic ZnIn2S4 using a metal-organic framework (MOF) as the template. We found that the sulfur vacancies in ZnIn2S4 enabled extremely fast NO2 detection with high response at room temperature (RT), and the material with high sulfur vacancy content delivers a 2 times higher response to 10 ppm NO2 than the device with low sulfur vacancy content. To unveil the crucial role played by sulfur vacancies, DFT calculations were conducted to reveal that sulfur vacancies greatly enhance the interaction and electron transfer between ZnIn2S4 and NO2. This study will provide hints for the engineering of bimetallic sulfide materials for low-power gas sensors at RT.

Synthesis and Electrocatalytic Applications of Layer-Structured Metal Chalcogenides Composites

Featured with the attractive properties such as large surface area, unique atomic layer thickness, excellent electronic conductivity, and superior catalytic activity, layered metal chalcogenides (LMCs) have received considerable research attention in electrocatalytic applications. In this review, the approaches developed to synthesize LMCs-based electrocatalysts are summarized. Recent progress in LMCs-based composites for electrochemical energy conversion applications including oxygen reduction reaction, carbon dioxide reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, overall water splitting, and nitrogen reduction reaction is reviewed, and the potential opportunities and practical obstacles for the development of LMCs-based composites as high-performing active substances for electrocatalytic applications are also discussed. This review may provide an inspiring guidance for developing high-performance LMCs for electrochemical energy conversion applications.

Designing Z-scheme In2O3 @ZnIn2S4 core-shell heterojunctions for enhanced photocatalytic multi-pollutant removal

In water bodies, the coexistence of and interaction between multiple pollutants complicate remediation. In this study, the In2O3 @ZnIn2S4 Z-scheme heterojunction with a stratified core-shell structure was constructed and used to remove multiple pollutants (tetracycline hydrochloride and Cr(VI)). The large number of active sites and the mechanism of photogenerated charge separation ensured the substantially enhanced catalytic activity of this photocatalyst, making it superior to In2O3 nanospheres and pure ZnIn2S4. The optimised In2O3 @ZnIn2S4 nano-flowers (In2O3 @ZnIn2S4 NFs) realised 99.8% removal of tetracycline hydrochloride and 100% removal of Cr(VI) within 60 min under visible-light. The material's high stability was demonstrated by five experiment cycles. Effects of organics, inorganics, and pH about the photocatalytic performance of the optimised In2O3 @ZnIn2S4 NFs when tetracycline hydrochloride and Cr(VI) coexist were also explored. Finally, the intermediates and degradation pathways were analysed, and the possible photocatalytic mechanism was also investigated by performing density functional theory calculations.

Turning trash to treasure: Innovative use of exhausted desiccant waste supported zinc indium sulphide for sustainable photocatalytic abatement of tetracycline

Employing an affordable and sustainable visible-light-driven system is crucial for organic pollutant abatement, in the field of photocatalysis. In the present investigation, a pioneering photocatalyst zinc indium sulphide, ZnIn2S4 (ZIS) supported on a silica gel matrix, SiO2 (SG) which is the leftover material after multiple rounds of dehumidification processes, was synthesized. The fabrication of the heterojunction facilitated enhancement in light absorption and charge separation efficiency. The photocatalytic performance was evaluated through the degradation of tetracycline (TC) under light irradiation. The nano-photocatalyst experienced detailed analysis using spectroscopic and microscopic methods. The ZIS/SG catalyst exhibited remarkable efficiency in degrading TC under visible light conditions, achieving a nearly 98-99% degradation. This performance surpassed the degradation rates of the original ZIS and SG catalysts by 3.6 and 4.45 times, respectively. Additionally, the catalyst was effectively used to control TC levels in real-time within pharmaceutical plant effluent, resulting in a degradation efficiency of 78.2%. With affordability, enhanced TC mineralization, and recyclability for up to six runs (efficiency ∼ 85%), the ZIS/SG photocatalyst exhibits desirable qualities of an ideal one. This innovative nano-photocatalyst introduces new possibilities for improving the process of photocatalytic decontamination of tenacious emerging pollutants by providing satisfactory reusability and stability.

rh-In2O3 Nanoparticles for Efficient Photocatalytic Degradation of Rifampin

Photodegradation, a widely accepted and promising technology, has gained significant attention for addressing the escalating concerns of environmental deterioration. In this article, rhombohedral corundum-type In2O3 nanocrystals were obtained from the transformation of InOOH via a simple calcining process. Under ultraviolet light irradiation, they showed higher photocatalytic activity in the decomposition of rifampin compared to that of the cubic phase In2O3 and P25-TiO2. Furthermore, the probable pathway and the feasible mechanism for the degradation of rifampin were also deeply explored and discussed.

Enhanced photocatalytic degradation performance of In2O3/g-C3N4 composites by coupling with H2O2

Environmental pollution by organic pollutants poses a great threat to the ecosystem and human development. Solar-powered catalytic oxidation technology can solve the existing energy and pollution crisis. Hence, in this work, cubic nano-In₂O₃ modified g-C₃N₄ composite was synthesized by in situ calcination, then it was coupled with hydrogen peroxide for the degradation of antibiotic under visible light. The results of SEM and XPS showed that In₂O₃ and g-C₃N₄ were closely combined. The catalytic oxidation efficiency of the antibiotic doxycycline was greatly improved when the as-prepared compound was coupled with hydrogen peroxide, and 88.2% of doxycycline was degraded within 80 min. By designing the active species inhibition test, it was found that a large number of hydroxyl radicals were generated in the system after adding hydrogen peroxide, which accelerated the degradation of the target. Hydrogen peroxide not only acts as a source of hydroxyl radical, but also as an active electron acceptor, which promotes the separation of photogenerated electron-hole pairs in the composite photocatalyst. Therefore, the double oxidation system formed by In₂O₃/g-C₃N₄ coupled with hydrogen peroxide can degrade the target at a higher rate. This work provided a research basis for the synthesis of In₂O₃ with regular morphology and simplified synthesis of In₂O₃/g-C₃N₄, and explored the practicability of the coupling method of double advanced oxidation for pollutant degradation.

Constructing Z-scheme 1D/2D heterojunction of ZnIn2S4 nanosheets decorated WO3 nanorods to enhance Cr(VI) photocatalytic reduction and rhodamine B degradation

Photocatalysis has been vastly employed as a feasible and efficient strategy for the removal of environmental pollutants. In this study, a well-designed core-shell heterojunction of WO3 decorated with ZnIn2S4 nanosheets were fabricated under mild in-situ conditions, and fabricated processes were systematically investigated with different fabrication durations. The coupling of WO3 and ZnIn2S4 (ZIS) resulted in a Z-scheme mechanism for charge carrier transfer, holding the respective redox capacity. The as-prepared 1D/2D WO3@ZIS heterostructure displayed the highest removal efficiency within 30 min for 25 mg L-1 Cr(VI), 89.3 and 29.7 times higher than pure WO3 and ZnIn2S4. 1D/2D WO3@ZIS remained excellently stable after 5 cycling experiments. Moreover, 40 mg L-1 RhB could be degraded within 50 min. The broad and short photogenerated electron transportation path is guaranteed by the 1D/2D and Z-scheme charge separation mechanism. It efficiently prevented photo-generated charge carriers from recombination, resulting in a longer carrier lifespan and better photocurrent responses than that of pure ones. This photocatalytic system showed promising results and also provides a framework for an efficient system for photocatalysis with potential for environmental application.

Construction of a dual-signal molecularly imprinted photoelectrochemical sensor based on bias potential control for selective sensing of tetracycline

The two signals validate each other to improve the accuracy and sensitivity of the MIP-PEC sensor.

Smartphone-Based Photoelectrochemical Immunoassay with Co9S8@ZnIn2S4 for Point-of-Care Diagnosis of Breast Cancer Biomarker

Photoelectrochemical immunoassays incorporating specific antigen-antibody recognition reactions with the photon-electron conversion capabilities of photocatalysts have been developed for biomarker detection, but most involve bulky and expensive equipment and are unsuitable for point-of-care testing. Herein, a portable smartphone-based photoelectrochemical immunoassay was innovatively designed for the on-site detection of breast cancer biomarkers (human epidermal growth factor receptor 2; HER2). The system consists of a split-type immunoassay mode, disposable screen-printed electrode covered with hierarchical Co9S8@ZnIn2S4 heterostructures, an integrated circuit board, and a Bluetooth smartphone equipped with a specially designed app. Using alkaline phosphatase (ALP) catalytic strategy to in situ generate ascorbic acid (AA) for electron-donating toward Co9S8@ZnIn2S4 heterostructures, an immunoreaction was successfully constructed for the HER2 detection in the real sample due to the positive correlation of the photocurrent signal to electron donor concentration. Differential charge density indicates that the formation of Co9S8@ZnIn2S4 heterojunction can facilitate the flow of charges in the interface and enhance the photocurrent of the composite. More importantly, the measured photocurrent signal can be wirelessly transmitted to the software and displayed on the smartphone screen to obtain the corresponding HER2 concentration value. The photocurrent values linearly with the logarithm of HER2 concentrations range spanned from 0.01 ng/mL to 10 ng/mL with a detection limit of 3.5 pg/mL. Impressively, the clinical serum specimen results obtained by the proposed method and the wireless sensing device are in good agreement with the enzyme-linked immunosorbent assay (ELISA).

In suit constructing S-scheme FeOOH/MgIn2S4 heterojunction with boosted interfacial charge separation and redox activity for efficiently eliminating antibiotic pollutant

Photocatalytic elimination of antibiotic pollutant is an appealing avenue in response to the water contamination, but it still suffers from sluggish charge detachment, limited redox capacity as well as poor visible light utilization. Herein, a particular S-scheme FeOOH/MgIn₂S₄ heterojunction with wide visible light absorption was triumphantly constructed by in-situ growth of MgIn₂S₄ nanoparticles onto the surface of FeOOH nanorods, and employed as a high-efficiency visible light driven photocatalyst for removing tetracycline (TC). Conspicuously, the as-obtained FeOOH(15 wt%)/MgIn₂S₄ elucidated the optimal TC removal rate of 0.01258 min^-1 after 100 min of visible light illumination, which was almost 33.1 and 6.6 times larger than those of neat FeOOH and MgIn₂S₄, separately. The exceptional degradation performance was principally put down to the establishment of S-scheme heterojunction between FeOOH and MgIn₂S₄, which could not merely accelerate the detachment of photogenerated carriers, but also retain the powerful reducing ability of photoinduced electrons for MgIn₂S₄ and high oxidizing capacity of photoexcited holes for FeOOH, strongly driving the generation of plentiful active species including holes, superoxide and hydroxyl radicals. Additionally, the possible degradation mechanism and pathways of TC were also speculated. This work offers a valuable perspective for constructing high-efficiency S-scheme heterojunction photocatalysts for eradicating antibiotics.

Thin In-Plane In2 O3 /ZnIn2 S4 Heterostructure Formed by Topological-Atom-Extraction: Optimal Distance and Charge Transfer for Effective CO2 Photoreduction

Exploitation of atomic-level principles to optimize the charge transfer on ultrathin 2D heterostructures is an emerging frontier in relieving the energy and environmental crisis. Herein, a facile "topological-atom-extraction" protocol is disclosed, i.e., selective extraction of Zn from ultrathin half-unit-cell ZnIn₂ S₄ (HZIS) can embed thin In₂ O₃ domain into 1.60 nm thick HZIS layer to create an atomically thin in-plane In₂ O₃ /HZIS heterostructure. Thanks to the optimal distance and capability of charge separation, the in-plane In₂ O₃ /HZIS heterostructure is among the best ZnIn₂ S₄ -based CO₂ reduction reaction (CRR) photocatalysts, and indeed demonstrates a significant increase (from 6.8- to 128-fold) in CO production rate compared with those of out-plane ZIS@In₂ O₃ and out-plane In₂ O₃ -HZIS_calcined heterostructures. Density Functional Theory simulation reveals that whereas the out-plane heterostructure has a much smaller ∆q of 0.2-0.25 e, the in-plane heterostructure with "zero distance contact" has an optimal ∆q of 1.05 e between In₂ O₃ and HZIS that induces remarkable charge redistribution on the in-plane heterojunction interface and creates local electric field confined within the ultrathin layer. The charge redistribution efficiently directs the charge-carrier separation in S-scheme photocatalytic system and endows long-lifetime carrier to CRR active HZIS. The findings demonstrate the strong versatility of engineering atomic-level heterojunctions for efficient catalysts design.

Preparation, Characterization and Application of Epitaxial Grown BiOBr (110) Film on ZnFe2O4 Surface with Enhanced Photocatalytic Fenton Oxidation Properties

A novel BiOBr photocatalyst was epitaxially grown in situ onto the surface of ZnFe₂O₄, a ferroelectric material with a strong polarization effect. The formatted BiOBr/ZnFe₂O₄ composite (BOB/ZFO) showed excellent photocatalytic degradation performance of tetracycline antibiotics (TCs). One of the composites with ZnFe₂O₄ content of 10% (BOB/ZFO-10) showed the best properties; the degradation efficiency of TCs upon visible light irradiation for 180 min was 99.2%, which was 3.58 times higher than that of pure phase BiOBr. The functions of ZnFe₂O₄ are assumed to be such that the addition of this ferroeletric material not only regulated the spontaneous polarization of BiOBr in the process of synthesis, but also resulted in the construction of Z-scheme heterostructures due to the appropriate staggered band structure of BiOBr and ZnFe₂O₄. In the presence of ferroelectric material ZnFe₂O₄, the local structure of BiOBr may be distorted accordingly, resulting in preferential growth of a (110) crystal facet of BiOBr and enhancement of spontaneous polarization, which promotes the efficient separation of photogenerated electron-hole pairs of ZnFe₂O₄ and BiOBr, and therefore enhances the redox capacity of the photocatalytic degradation of organic pollutants.

Self-powered photoelectrochemical aptasensor based on MIL-68(In) derived In2O3 hollow nanotubes and Ag doped ZnIn2S4 quantum dots for oxytetracycline detection

A self-powered photoelectrochemical (PEC) aptasensor was constructed based on MIL-68(In) derived indium oxide hollow nanotubes (In₂O₃ HNs) and Ag-doped ZnIn₂S₄ quantum dots (QDs) as sensing matrix for the ultrasensitive detection of oxytetracycline (OTC). The hollow tube structure of the designed photoelectric active platform provided abundant active sites and a larger specific surface area for the immobilization of target recognition unit. The coupling of Ag:ZnIn₂S₄ QDs and In₂O₃ HNs can accelerate the transmit and separation of photoinduced charge, and thus greatly increasing the intensity of photocurrent signal. Then, the well-constructed OTC-aptamer was anchored on the modified photoelectrode as an accurate capturing element, achieving the specific detection of analyte. Under optimal conditions, the photocurrent intensity of the PEC aptasensor decreases linearly, with a linear response range of 10^-4 -10 nmol/L, and a limit of detection (LOD) of 3.3 × 10^-5 nmol/L (S/N = 3). The developed self-powered aptasensor with excellent reproducibility, stability, and selectivity, provides a potential way to detect antibiotic residues in environmental media.

MOF-derived N-doped ZnO carbon skeleton@hierarchical Bi2MoO6 S-scheme heterojunction for photodegradation of SMX: Mechanism, pathways and DFT calculation

Semiconductor photocatalytic degradation of pollutants is considered to be one of the promising sustainable energy routes. Nevertheless, it is challenging for photocatalysts to have excellent visible light absorption and suppress photo-generated electron-hole recombination at the same time. Here, we prepared nitrogen-doped ZnO carbon skeleton by directly calcining the metal-organic framework. Then hierarchical Bi₂MoO₆ nanosheets are grown in situ on its surface to synthesize S-scheme heterojunction. This special 3D layered and oxygen vacancies work together to make photo-generated electrons and holes easier to separate and migrate. Therefore, the pseudo-first-order kinetic constant of N-doped ZnO carbon skeleton@Bi₂MoO₆ degradation of sulfamethoxazole reaches 0.022 min^-1, which is almost 10 times that of ZIF-8 derived ZnO and 27.5 times Bi₂MoO₆ under visible light irradiation. Meanwhile, the mechanism of driving charge transfer of S-scheme heterojunction, and the photocatalytic degradation pathway of sulfamethoxazole are also analyzed. This work will provide a new way to construct S-scheme heterojunction photocatalyst to degrade antibiotic pollutants.

Thin films composed of Zr-doped In2O3 grains rich in fracture surfaces and cracks for photoelectrochemical water oxidation

Zr-doped In₂O₃ thin films are prepared on FTO substrates by a two-step method: firstly, Zr-doped In(OH)₃ thin films are hydrothermally deposited, and then converted to Zr-doped In₂O₃ films by heat treatment. It is found that during the phase transition from Zr-doped In(OH)₃ to Zr-doped In₂O₃, the cuboid-like crystal grains will fragment, resulting in a large number of new surfaces and cracks. Zr doping can introduce shallow impurity levels in the band gap of In₂O₃, which will enhance the absorption of incident light. The substitution of trivalent In³⁺ ions by tetravalent Zr⁴⁺ ions provides additional donors for In₂O₃, which reduces the charge transfer resistance of the photoelectrochemical water oxidation and thus improves the charge transfer kinetics. These factors synergistically improve the photoelectrochemical water oxidation performance of Zr-doped In₂O₃. For example, at a potential of 1.5 V versus reversible hydrogen electrode, the photocurrent density of the Zr-doped In₂O₃ electrode during photoelectrochemical water splitting can be as high as about 3.5 times that of the undoped In₂O₃. Furthermore, Zr doping will also cause changes in the nucleation of some In(OH)₃ grains, resulting in the formation of a small number of rod-bundle-shaped grains.

Anchoring ZnIn2S4 nanosheets on ZSM-5 for boosting photocatalytic Cr(vi) reduction

ZSM-5@ZnIn2S4 is constructed for highly efficient photocatalytic Cr(vi) reduction.

Construction of three-dimensional MgIn2S4 nanoflowers/two-dimensional oxygen-doped g-C3N4 nanosheets direct Z-scheme heterojunctions for efficient Cr(VI) reduction: Insight into the role of superoxide radicals

Environmental crisis aroused from carcinogenic and mutagenic heavy metal Cr(VI)-containing wastewater has attracted great attention. Herein, a direct Z-scheme three-dimensional MgIn₂S₄ nanoflowers/two-dimensional oxygen-doped g-C₃N₄ nanosheets heterostructured composite photocatalysts were fabricated for Cr(VI) photoreduction. The crystalline structure, morphology, specific surface areas, chemical components, optical properties, as well as photoelectrochemical performance of the fabricated photocatalyst were systematically studied. All the hybrids photocatalysts exhibited superior Cr(VI) photoreduction performance than a single component. The optimal sample showed 2.0 and 343.7 times increasing than three-dimensional MgIn₂S₄ nanoflowers and two-dimensional oxygen-doped g-C₃N₄ nanosheets, respectively. The enhancement of the Cr(VI) photoreduction performance could be ascribed to the enhanced specific surface areas, the improved light absorption, and the Z-scheme charge carriers' separation and migration pathway. Moreover, the role of superoxide radicals was investigated. It is speculated that this research would present a new sight toward photocatalytic Cr(VI) reduction.

ZnIn2 S4 -Based Photocatalysts for Energy and Environmental Applications

As a fascinating visible-light-responsive photocatalyst, zinc indium sulfide (ZnIn₂ S₄ ) has attracted extensive interdisciplinary interest and is expected to become a new research hotspot in the near future, due to its nontoxicity, suitable band gap, high physicochemical stability and durability, ease of synthesis, and appealing catalytic activity. This review provides an overview on the recent advances in ZnIn₂ S₄ -based photocatalysts. First, the crystal structures and band structures of ZnIn₂ S₄ are briefly introduced. Then, various modulation strategies of ZnIn₂ S₄ are outlined for better photocatalytic performance, which includes morphology and structure engineering, vacancy engineering, doping engineering, hydrogenation engineering, and the construction of ZnIn₂ S₄ -based composites. Thereafter, the potential applications in the energy and environmental area of ZnIn₂ S₄ -based photocatalysts are summarized. Finally, some personal perspectives about the promises and prospects of this emerging material are provided.

3D hollow MXene@ZnIn2S4 heterojunction with rich zinc vacancies for highly efficient visible-light photocatalytic reduction

Well-designed heterojunction semicounductor coupled with high-conductive cocatalyst can obtain boosted photocatalytic activity. Herein, a novel three-dimensional (3D) hollow heterojunction was prepared by coating the indium zinc sulfide (ZnIn₂S₄) nanosheets with rich-zinc vacancies (V_Zn) on 3D hollow titanium carbide (Ti₃C₂). The obtained 3D hollow heterojunction (Ti₃C₂@ZnIn₂S₄) achieved effective optical collection and promoted the separation and transmission of photogenerated carriers as well as the surface reaction of spatial separation. In addition, time-resolved photoluminescence and steady-state photoluminescence spectra indicated that the existence of V_Zn and the introduction of hollow Ti₃C₂ spherical shell effectively inhibited the recombination of photogenerated carriers and accelerated their separation and transmission, thus further enhancing the photocatalytic activity. In addition, the introduction of 3D hollow Ti₃C₂ benefited a larger specific surface area for heavy metal adsorption. Due to the unique structural and compositional characteristics, the heterojunction showed high efficiency of Cr(VI) reduction under visible light. In particular, the optimal Ti₃C₂@ZnIn₂S₄ heterojunction (1%-Ti₃C₂@ZnIn₂S₄) achieved 100% removal of Cr(VI) within 25 min, with a reaction rate constant of 0.225, which was 8.5 times higher than that of the pristine ZnIn₂S₄. The superior reusability and structural stability further indicated the MXene-based novel photocatalyst is promising for application in environmental remediation.

Fabrication of size-controlled hierarchical ZnS@ZnIn2S4 heterostructured cages for enhanced gas-phase CO2 photoreduction

Designing and constructing advanced heterojunction architectures are desirable for boosting CO₂ photoreduction performance of semiconductor photocatalysts. Herein, we have prepared hierarchical ZnS@ZnIn₂S₄ core-shell cages with controlled particle sizes using sequential synthesis of Zeolitic imidazolate (ZIF-8) polyhedrons, ZnS cages, and ZnIn₂S₄ nanosheets on the ZnS polyhedron cages. ZIF-8 polyhedrons are firstly synthesized by a liquid-phase approach. The subsequent sulfidation of the ZIF-8 polyhedrons results in the formation of ZnS polyhedron cages, which act as substrates for fabricating ZnS@ZnIn₂S₄ core-shell cages by growing ZnIn₂S₄ nanosheets. The size of ZnS cages can be tuned to optimize CO₂ photoreduction performance of hierarchical ZnS@ZnIn₂S₄ core-shell cages. The synergy of the unique hierarchical core-shell cage-like structure and heterojunction composition endows the hybrid catalyst high incident light utilization, abundant active sites, and effective separation of photoexcited charge carriers. Benefiting from these advantages, the optimized hierarchical ZnS@ZnIn₂S₄ core-shell cages exhibit enhanced performance for CO₂ photoreduction with the CO yield of 87.43 μmol h^-1g^-1 and 84.3% selectivity, which are much superior to those of single ZnIn₂S₄ or ZnS. Upon Au decoration, the CO₂ photoreduction performance of ZnS@ZnIn₂S₄ core-shell cages is further enhanced because of the Schottky junctions and surface plasmon resonance effect.

Construction of Porous Tubular In2S3@In2O3 with Plasma Treatment-Derived Oxygen Vacancies for Efficient Photocatalytic H2O2 Production in Pure Water Via Two-Electron Reduction

Tubular In₂O₃ was fabricated by the annealing of In-MIL-68 and further treated by Ar plasma to yield oxygen vacancies (O_v) followed by the growth of In₂S₃ nanoflowers. Unexpectedly, the resulting porous In₂S₃@In₂O₃ composites were discovered to display a broad visible-light response and especially enhanced capacities for efficient photocatalytic production of H₂O₂ in pure water, with a rate of 4.59 μmol·g^-1·min^-1. An apparent quantum yield of 28.9% at 420 nm can also be expected without the use of noble metals or organic scavengers. Herein, the high light utilization might be profited from their porous tubular heterostructure for powerful "light captivity". Moreover, the Ar plasma-derived O_v sites on the composites might tune the H₂O₂ generation route from the single-electron reduction to the two-electron one toward the significantly enhanced photocatalysis, as validated by the Koutecky-Levich plots. This work demonstrates a new perspective of designing porous heterostructures with the advantages of high light harvest and plasma-derived O_v active sites. Importantly, it may provide a promising defect-induced strategy of two-electron reduction triggered by the plasma treatment for the efficient photocatalytic H₂O₂ production under visible light.

Which is Better for Nanomedicines: Nanocatalysts or Single-Atom Catalysts?

With the rapid advancements in nanotechnology and materials science, numerous nanomaterials have been used as catalysts for nanomedical applications. Their design and modification according to the microenvironment of diseases have been shown to achieve effective treatment. Chemists are in pursuit of nanocatalysts that are more efficient, controllable, and less toxic by developing innovative synthetic technologies and improving existing ones. Recently, single-atom catalysts (SACs) with excellent catalytic activity and high selectivity have attracted increasing attention because of their accurate design as nanomaterials at the atomic level, thereby highlighting their potential for nanomedical applications. In this review, the recent advances in nanocatalysts and SACs are briefly summarized according to their synthesis, characterizations, catalytic mechanisms, and nanomedical applications. The opportunities and future scope for their development and the issues and challenges for their application as nanomedicine are also discussed. As far as it is known, the review is the systematic comparison of nanocatalysts and SACs, especially in the field of nanomedicine, which has promoted the development of nanocatalytic medicine.

Structural design toward functional materials by electrospinning: A review

Electrospinning as one of the most versatile technologies have attracted a lot of scientists’ interests in past decades due to its great diversity of fabricating nanofibers featuring high aspect ratio, large specific surface area, flexibility, structural abundance, and surface functionality. Remarkable progress has been made in terms of the versatile structures of electrospun fibers and great functionalities to enable a broad spectrum of applications. In this article, the electrospun fibers with different structures and their applications are reviewed. First, several kinds of electrospun fibers with different structures are presented. Then the applications of various structural electrospun fibers in different fields, including catalysis, drug release, batteries, and supercapacitors, are reviewed. Finally, the application prospect and main challenges of electrospun fibers are discussed. We hope that this review will provide readers with a comprehensive understanding of the structural design and applications of electrospun fibers in different fields.