Composition Directed Generation of Reactive Oxygen Species in Irradiated Mixed Metal Sulfides Correlated with Their Photocatalytic Activities

Antimicrobial photodynamic inactivation pH-responsive films based on gelatin/chitosan incorporated with aloe-emodin

Using novel active food packaging has gradually become a daily necessity in terms of impeding microbial contamination. Here, an antimicrobial photodynamic inactivation (PDI) pH-responsive film is developed by incorporating aloe-emodin (AE) into a vehicle of gelatin/chitosan (GC). Besides enhancement in hydrophobicity, the well-dispersed crystals of AE in the GC matrix by hydrogen bonding can upgrade the film's mechanical strength and barrier. The matrix is capable of regulating the release of AE in response to acidic stimuli by a combination mechanism of diffusion and polymer relaxation. Being benefitted from the inherent bioactivity of AE and the PDI activity under visible light irradiation (i.e., 456 nm), the target film of GC-AE2 has excellent antibacterial effect towards Staphylococcus aureus and Escherichia coli, showing bacterial viability of 9.93 ± 1.33 % and 14.85 ± 1.16 %, respectively. Furthermore, the film can effectively thwart Botrytis cinerea infection in cherry tomatoes, demonstrating its potential in preventing the microbial spoilage of postharvest fruits.

Type I photodynamic antimicrobial therapy: Principles, progress, and future perspectives

The emergence of drug-resistant bacteria has significantly diminished the efficacy of existing antibiotics in the treatment of bacterial infections. Consequently, the need for finding a strategy capable of effectively combating bacterial infections has become increasingly urgent. Photodynamic therapy (PDT) is considered one of the most promising emerging antibacterial strategies due to its non-invasiveness, low adverse effect, and the fact that it does not lead to the development of drug resistance. However, bacteria at the infection sites often exist in the form of biofilm instead of the planktonic form, resulting in a hypoxic microenvironment. This phenomenon compromises the treatment outcome of oxygen-dependent type-II PDT. Compared to type-II PDT, type-I PDT is not constrained by the oxygen concentration in the infected tissues. Therefore, in the treatment of bacterial infections, type-I PDT exhibits significant advantages over type-II PDT. In this review, we first introduce the fundamental principles of type-I PDT in details, including its physicochemical properties and how it generates reactive oxygen species (ROS). Next, we explore several specific antimicrobial mechanisms utilized by type-I PDT and summarize the recent applications of type-I PDT in antimicrobial treatment. Finally, the limitations and future development directions of type-I photosensitizers are discussed. STATEMENT OF SIGNIFICANCE: The misuse and overuse of antibiotics have accelerated the development of bacterial resistance. To achieve the effective eradication of resistant bacteria, pathfinders have devised various treatment strategies. Among these strategies, type I photodynamic therapy has garnered considerable attention owing to its non-oxygen dependence. The utilization of non-oxygen-dependent photodynamic therapy not only enables the effective elimination of drug-resistant bacteria but also facilitates the successful eradication of hypoxic biofilms, which exhibits promising prospects for treating biofilm-associated infections. Based on the current research status, we anticipate that the novel type I photodynamic therapy agent can surmount the biofilm barrier, enabling efficient treatment of hypoxic biofilm infections.

Rational design of full-spectrum visible-light-responsive bimetallic sulfide Bi2S3/CoS2 composites for high-efficiency photocatalytic degradation of naproxen and bacterial inactivation

Photocatalytic water decontamination has emerged as a highly promising technology for efficient and rapid water treatment, harnessing sustainable solar energy as its driving force. In this study, we prepared visible-light active Bi2S3/CoS2 composites for the degradation of naproxen (NPX) and the inactivation of Escherichia coli (E. coli). The homogeneous dispersion of CoS2 was stably integrated with Bi2S3, resulting in a significant enhancement of the specific surface area, efficient utilization of visible light, and effective separation of photogenerated charge carriers. Consequently, this synergistic photocatalytic system greatly facilitated the successful degradation of NPX and the inactivation of E. coli under visible-light irradiation. Compared to the pure Bi2S3 and CoS2 catalysts, the Bi2S3/CoS2 (1:2) composites displayed significantly enhanced photodegradation activity, achieving 96.46% (k = 0.2847 min-1) degradation of NPX within 90 min and maintaining good recyclability with no significant decline after six successive cycles. Additionally, the photocatalytic inactivation of E. coli results indicated that Bi2S3/CoS2 composites exhibited excellent performance, leading to the inactivation of 7 log10 cfu mL-1 of bacterial cells after 150 min of visible-light exposure. Scanning Electron Microscopy (SEM) and K+ ions leakage tests demonstrated that the destruction of the E. coli cell membrane structure resulted in cell death. The outcomes of this work suggest that Bi2S3/CoS2 composites hold significant potential for treating water contaminated with antibiotic and microbial pollutants.

Photocatalytic Antimicrobials: Principles, Design Strategies, and Applications

Nowadays, the increasing emergence of antibiotic-resistant pathogenic microorganisms requires the search for alternative methods that do not cause drug resistance. Phototherapy strategies (PTs) based on the photoresponsive materials have become a new trend in the inactivation of pathogenic microorganisms due to their spatiotemporal controllability and negligible side effects. Among those phototherapy strategies, photocatalytic antimicrobial therapy (PCAT) has emerged as an effective and promising antimicrobial strategy in recent years. In the process of photocatalytic treatment, photocatalytic materials are excited by different wavelengths of lights to produce reactive oxygen species (ROS) or other toxic species for the killing of various pathogenic microbes, such as bacteria, viruses, fungi, parasites, and algae. Therefore, this review timely summarizes the latest progress in the PCAT field, with emphasis on the development of various photocatalytic antimicrobials (PCAMs), the underlying antimicrobial mechanisms, the design strategies, and the multiple practical antimicrobial applications in local infections therapy, personal protective equipment, water purification, antimicrobial coatings, wound dressings, food safety, antibacterial textiles, and air purification. Meanwhile, we also present the challenges and perspectives of widespread practical implementation of PCAT as antimicrobial therapeutics. We hope that as a result of this review, PCAT will flourish and become an effective weapon against pathogenic microorganisms and antibiotic resistance.

Recent advances in TiO2/ZnS-based binary and ternary photocatalysts for the degradation of organic pollutants

Semiconductor-mediated photocatalysis plays a pivotal role in the elimination of organic pollutants from water systems. Titanium dioxide (TiO₂) and zinc sulphide (ZnS) semiconductors are commonly utilized as photocatalysts in water purification due to their physical and chemical stability and also large band gap. The drawbacks of both semiconductors, nevertheless, prevent them from being used in real and large-scale treatments. Therefore, binary and ternary-based TiO₂/ZnS nanostructured materials may be a promising solution to improve the quantum efficiency, structural, and electrical features of pure TiO₂ and ZnS semiconductors for improved photoefficiency. This review aims to unravel the development of binary TiO₂/ZnS and the modification of ternary photocatalysts (TiO₂/ZnS-X, X = metal, non-metal, and dye sensitization) by various approaches. The engineered TiO₂/ZnS-based ternary nanostructured materials have exhibited exceptional performance to accelerate the degradation of organic pollutants in wastewater. These materials were fabricated by modifying TiO₂/ZnS binary composite and embedding co-catalysts like carbonaceous material, polymeric material, transition metal, metal oxide, and metal. The relationship between the properties of the resulting nanomaterials and their photocatalytic performances has been examined. This review has also placed a special focus on the synthetic routes applied to derive the binary and ternary TiO₂/ZnS composites. Another aim of this review is to scrutinize the factors that influence the performance of binary and ternary-based TiO₂/ZnS composites on the degradation of organic pollutants. Opportunities for further investigation have been also outlined, along with limitations and impediments based on the current findings.

An overview of nanomaterial-based novel disinfection technologies for harmful microorganisms: Mechanism, synthesis, devices and application

Harmful microorganism (e.g., new coronavirus) based infection is the most important security concern in life sciences and healthcare. This article aims to provide a state-of-the-art review on the development of advanced technology based on nanomaterial disinfection/sterilization techniques (NDST) for the first time including the nanomaterial types, disinfection techniques, bactericidal devices, sterilization products, and application scenarios (i.e., water, air, medical healthcare), with particular brief account of bactericidal behaviors referring to varied systems. In this emerging research area spanning the years from 1998 to 2021, total of ~200 publications selected for the type of review paper and research articles were reviewed. Four typical functional materials (namely type of metal/metal oxides, S-based, C-based, and N-based) with their development progresses in disinfection/sterilization are summarized with a list of synthesis and design. Among them, the widely used silver nanoparticles (AgNPs) are considered as the most effective bacterial agents in the type of nanomaterials at present and has been reported for inactivation of viruses, fungi, protozoa. Some methodologies against (1) disinfection by-products (DBPs) in traditional sterilization, (2) noble metal nanoparticles (NPs) agglomeration and release, (3) toxic metal leaching, (4) solar spectral response broadening, and (5) photogenerated e^-/h⁺ pairs recombination are reviewed and discussed in this field, namely (1) alternative techniques and nanomaterials, (2) supporter anchoring effect, (3) nonmetal functional nanomaterials, (4) element doping, and (5) heterojunction constructing. The feasible strategies in the perspective of NDST are proposed to involve (1) non-noble metal disinfectors, (2) multi-functional nanomaterials, (3) multi-component nanocomposite innovation, and (4) hybrid techniques for disinfection/sterilization system. It is promising to achieve 100% bactericidal efficiency for 10⁸ CFU/mL within a short time of less than 30 min.

Applications of electron spin resonance spectroscopy in photoinduced nanomaterial charge separation and reactive oxygen species generation

Nano-metals, nano-metal oxides, and carbon-based nanomaterials exhibit superior solar-to-chemical/photo-electron transfer properties and are potential candidates for environmental remediations and energy transfer. Recent research effort focuses on enhancing the efficiency of photoinduced electron-hole separation to improve energy transfer in catalytic reactions. Electron spin resonance (ESR) spectroscopy has been used to monitor the generation of electron/hole and reactive oxygen species (ROS) during nanomaterial-mediated photocatalysis. Using ESR coupled with spin trapping and spin labeling techniques, the underlying photocatalytic mechanism involved in the nanomaterial-mediated photocatalysis was investigated. In this review, we briefly introduced ESR principle and summarized recent advancements using ESR spectroscopy to characterize electron-hole separation and ROS production by different types of nanomaterials.

Photocatalytic Hydrogen Evolution Coupled with Production of Highly Value-Added Organic Chemicals by a Composite Photocatalyst CdIn2 S4 @MIL-53-SO3 Ni1/2

Photocatalytic water splitting coupled with the production of highly value-added organic chemicals is of significant importance, which represents a very promising pathway for transforming green solar energy into chemical energy. Herein, we report a composite photocatalyst CdIn₂ S₄ @MIL-53-SO₃ Ni_1/2 , which is highly efficient on prompting water splitting for the production of H₂ in the reduction half-reaction and selective oxidation of organic molecules for the production of highly value-added organic chemicals in the oxidation half-reaction under visible light irradiation. The superior photocatalytic properties of the composite photocatalyst CdIn₂ S₄ @MIL-53-SO₃ Ni_1/2 should be ascribed to coating suspended ion catalyst (SIC), consisting of redox-active Ni^II ions in the anionic pores of coordination network MIL-53-SO₃ ^- , on the surface of photoactive CdIn₂ S₄ , which endows photogenerated electron-hole pairs separate more efficiently for high rate production of H₂ and selective production of highly value-added organic products, demonstrating great potential for practical applications.

In situ construction of a direct Z-scheme CdIn2S4/TiO2 heterojunction for improving photocatalytic properties

Direct Z-scheme photocatalytic systems driven by visible light to eliminate organic pollutants in wastewater have become important scientific tools in the field of photocatalysis.

Theoretical Calculation of Hydrogen Generation and Delivery via Photocatalytic Water Splitting in Boron-Carbon-Nitride Nanotube/Metal Cluster Hybrid

Solar-driven water splitting is an appealing strategy to produce hydrogen energy. However, the non-negligible chance of reverse reactions due to a mixture of hydrogen molecules (H₂) with oxygen species poses challenges for safe H₂ collection and delivery, which hinders its applications. Using first-principles simulations, we propose a hybrid structure design where metal clusters of TM₄ (TM = Au/Pt) are encapsulated in boron-carbon-nitride nanotube (BCNNT) decorated with CuN₃ group. It can readily absorb ultraviolet-visible solar light to generate charge carriers. The energetic electrons and holes would be separately delivered to the reduction site of TM₄ and the oxidation site of the BCNNT layer. Then, protons generated by water dissociation at the BCNNT layer will penetrate through BCNNT and consequently meet electrons at the TM₄ site to be reduced into H₂. As a selective sieve, BCNNT prevents oxygen species from going inside and H₂ from crossing out so that H₂ can be completely isolated. Further, the sufficient space of the tubular cavity endows the transportation feasibility of the produced H₂ along the nanotube for collection. This proposed design combines photocatalytic hydrogen production and safe delivery, which may help in developing a practical solution for a photodriven hydrogen production.

Cadmium sulfide nanoparticles-assisted intimate coupling of microbial and photoelectrochemical processes: Mechanisms and environmental applications

Intimate coupling of microbial extracellular electron transfer (EET) and photoelectrochemical processes is an emerging research area with great potential to circumvent many disadvantages associated with traditional techniques that depend on independent microbial or photocatalysis treatment. Microbial EET processes involve microorganism oxidation of extracellular electron donors for respiration and synchronous reduction of extracellular electron acceptors to form an integrated respiratory chain. Coupled microbial EET-photoelectrochemical technologies greatly improve energy conversion efficiency providing both economic and environmental benefits. Among substitutes for semiconductor photocatalysts, cadmium sulfide nanoparticles (CdS NPs) possess several attractive properties. Specifically, CdS NPs have suitable electrical conductivity, large specific surface area, visible light-driven photocatalysis capability and robust biocompatibility, enabling them to promote hybrid microbial-photoelectrochemical processes. This review highlights recent advances in intimately coupled CdS NPs-microbial extracellular electron transfer systems and examines the mechanistic pathways involved in photoelectrochemical transformations. Finally, the prospects for emerging applications utilizing hybrid CdS NPs-based microbial-photoelectrochemical technologies are assessed. As such, this review provides a rigorous fundamental analysis of electron transport dynamics for hybrid CdS NPs-microbial photoelectrochemical processes and explores the applicability of engineered CdS NPs-biohybrids for future applications, such as in environmental remediation and clean-energy production.

The Effect of AgInS2, SnS, CuS2, Bi2S3 Quantum Dots on the Surface Properties and Photocatalytic Activity of QDs-Sensitized TiO2 Composite

The effect of type (AgInS2, SnS, CuS2, Bi2S3) and amount (5, 10, 15 wt%) of quantum dots (QDs) on the surface properties and photocatalytic activity of QDs-sensitized TiO2 composite, was investigated. AgInS2, SnS, CuS2, Bi2S3 QDs were obtained by hot-injection, sonochemical, microwave, and hot-injection method, respectively. To characterize of as-prepared samples high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis spectroscopy and photoluminescence (PL) emission spectroscopy were applied. The size of AgInS2, SnS, CuS2, Bi2S3 QDs were 12; 2–6; 2–3, and 1–2 nm, respectively. The QDs and QDs-sensitized TiO2 composites obtained have been tested in toluene degradation under LEDs light irradiation (λmax = 415 nm and λmax = 375 nm). For pristine QDs the efficiency of toluene degradation increased in the order of AgInS2 < Bi2S3 < CuS < SnS under 375 nm and AgInS2 < CuS < Bi2S3 < SnS under 415 nm. In the presence of TiO2/SnS QDs_15% composite, 91% of toluene was degraded after 1 h of irradiation, and this efficiency was about 12 higher than that for pristine QDs under 375 nm. Generally, building the TiO2/AgInS2 and TiO2/SnS exhibited higher photoactivity under 375 nm than the pristine TiO2 and QDs which suggests a synergistic effect between QDs and TiO2 matrix.

Rapid Removal of Azophloxine via Catalytic Degradation by a Novel Heterogeneous Catalyst under Visible Light

Azo dyes are the most widely used synthetic dyes in the printing and dyeing process. However, the discharge of untreated azo dyes poses a potential threat to aqueous ecosystems and human health. Herein, we fabricated a novel heterogeneous catalyst: activated-carbon-fiber-supported ferric alginate (FeAlg-ACF). Together with peroxymonosulfate (PMS) and visible light, this photocatalytic oxidation system was used to remove an azo dye—azophloxine. The results indicated that the proposed catalytic oxidation system can remove 100% of azophloxine within 24 min, while under the same system, the removal rates were only 92% and 84% when ferric alginate was replaced with ferric citrate and ferric oxalate, respectively, which showed the superiority of FeAlg-ACF. The degradation of azophloxine is achieved by the active radicals (SO4•− and •OH) released from PMS and persistent free radicals from activated carbon fiber. Moreover, due to ferric alginate’s highly intrinsic photosensitivity, visible radiation can further enhance the ligand-to-metal charge transfer (LMCT) processes. After 24 min of treatment, the total organic carbon of the azophloxine solution (50 μmol/L) decreased from 1.82 mg/L to 79.3 μg/L and the concentration of nitrate ions increased from 0.3 mg/L to 8.6 mg/L. That is, up to 93.5% of azophloxine molecules were completely degraded into inorganic compounds. Consequently, potential secondary contamination by intermediate organic products during catalytic degradation was prohibited. The azophloxine removal ratio was kept almost constant after seven cycles, indicating the recyclability and longevity of this system. Furthermore, the azophloxine removal was still promising at high concentrations of Cl−, HCO3−, and CO32−. Therefore, our proposed system is potentially effective at removing dye pollutants from seawater. It provides a feasible method for the development of efficient and environmentally friendly PMS activation technology combined with FeAlg-ACF, which has significant academic and application value.

Ternary Metal Chalcogenide Heterostructure (AgInS2-TiO2) Nanocomposites for Visible Light Photocatalytic Applications

Hybrid nanoarchitectures of AgInS2 and TiO2 photocatalysts were prepared by using a modified sol-gel method. The experimental results reveal that these nanocomposites display enhanced visible light absorption and effective charge carrier separation compared to their pristine parent samples (AgInS2 or TiO2). 0.5 wt % AgInS2 loading was found to be the optimum concentration for photocatalytic applications. More than 95% of doxycycline degradation was achieved within 180 min of solar light illumination. Similarly, the dopant concentrations at lower values (<2 wt %) exhibited 300 times higher H2 generation rate under visible light irradiation compared to AgInS2 and TiO2. The microbial strains (Escherichia coli and Staphylococcus aureus) exhibited a 99.999% reduction within half an hour of simulated solar light illumination. The computational investigation was employed to understand the structural, electronic, and the dielectric properties of AgInS2 and TiO2 composites. The improved photocatalytic results are explained as a result of the decreased rate of exciton recombination. The current investigation opens up new insights into the use of novel ternary heterostructure nanocomposites for improved visible light activity.

Application and mechanism of ferrihydrite in the EDDS improved heterogeneous photo-Fenton system: the role of different reactive species under different conditions

The application of carboxylic acid and natural iron oxide in heterogeneous AOP systems for the treatment of organic pollutants in water has attracted extensive attention.

Separation of charge carriers and generation of reactive oxygen species by TiO2 nanoparticles mixed with differently-coated gold nanorods under light irradiation

Combinations of semiconductor nanoparticles (NPs) with noble metal NPs enable an increase in the photoactivity of semiconductor NPs into the visible and near-infrared regions. The design rationale of the semiconductor-metal hybrid nanostructures for the optimization of charge carrier separation and reactive oxygen species (ROS) generation remains unclear. In this study, the interactions of Au nanorods (AuNRs) with TiO₂ NPs were modulated by controlling their surface charges. Positively charged AuNRs formed aggregates with the negatively charged TiO₂ NPs (AuNR@CTAB/TiO₂) upon mixing, suggesting that Schottky junctions may exist between Au and TiO₂. In contrast, negatively charged AuNRs (AuNR@PSS) remained spatially separated from the TiO₂ NPs in the mixed suspension (AuNR@PSS/TiO₂), owing to electrostatic repulsion. We used electron spin resonance (ESR) spectroscopy to detect the separation of charged carriers and ROS generation in these two mixtures under simulated sunlight irradiation. We also explored the role of dissolved oxygen in charge carrier separation and ROS generation by continuously introducing oxygen into the AuNR@CTAB/TiO₂ suspension under simulated sunlight irradiation. Moreover, the generation of ROS by the AuNR@CTAB/TiO₂ and AuNR@PSS/TiO₂ mixtures were also examined under 808 nm laser irradiation. Our results show that the photogenerated electrons of excited semiconductor NPs are readily transferred to noble metal NPs simply by collisions, but the transfer of photogenerated hot electrons from excited AuNRs to TiO₂ NPs is more stringent and requires the formation of Schottky junctions. In addition, the introduction of oxygen is an efficient way to enhance the photocatalytic activity of semiconductor NPs/noble metal NPs system combinations.

Exciton dissociation in an NIR-active triohybrid nanocrystal leading to efficient generation of reactive oxygen species

Lead sulfide (PbS) colloidal quantum dots (QDs) are emerging materials for fundamental studies because of their potential application in near infrared (NIR) light harvesting technologies. However, inefficient electron separation, facile charge recombination and defect state trapping of photoexcited carriers are reported as limitations of the PbS QDs to achieve efficient energy conversion. In the present study, we have synthesized a triohybrid by assembling a semiconductor titanium dioxide (TiO₂), an organic oxidizing molecule phenothiazine (PTZ) and PbS QDs. The triohybrid along with PbS_TiO₂ and PbS_PTZ hybrids has been characterized and the attachment of different components is verified by spectroscopic and microscopic techniques. The interfacial dynamics of the photoexcited carriers in the PbS_TiO₂ and PbS_PTZ hybrids have been investigated separately using steady state and time resolved photoluminescence (TRPL) measurements. The photoinduced electron transfer (PET) from the PbS QD to the conduction band (CB) of TiO₂ and photoinduced hole transfer (PHT) from the valence band (VB) of the QD to the highest occupied molecular orbital (HOMO) of PTZ have been observed and correlated mechanistically to the energy level alignments obtained from cyclic voltammetric (CV) analysis. The PTZ molecule is also found to act as a surface defect passivator of the PbS QD. Finally, simultaneous exciton dissociation and reduced back recombination phenomena have been correlated with a higher reactive oxygen species (ROS) generation activity of the triohybrid than the other two, under IR light irradiation. Thus, a detailed investigation of carrier dynamics and the mechanism of higher NIR light activity for a novel nanohybrid is explored and analyzed which could be beneficial for NIR catalysis or antibacterial activities.

A. Visible-light-induced degradation of rhodamine B by nanosized Ag2S–ZnS loaded on cellulose

Visible-light-active nanosized Ag₂S–ZnS loaded on cellulose photocatalysts are used for RhB dye degradation to a maximum extent in a short period of time and the catalysts can be reused many times.

Enhanced generation of reactive oxygen species and photocatalytic activity by Pt-based metallic nanostructures: the composition matters

The modification of semiconductor nanostructures with metallic nanocomponents can promote the separation of electron/hole from photoexited semiconductors by forming heterojunctions, thus exhibit enhanced photocatalytic activities and potential applications. In this study, Pt-based NPs, including Pt, PtCu, and PtCuCo are employed as model co-catalysts to comparatively study their capability to enhance the photocatalytic activity of TiO₂ nanosheets. It was found that each of Pt, PtCu, and PtCuCo can greatly enhance the photocatalytic activity of TiO₂ toward degradation of organic dyes. Using electron spin resonance spectroscopy, we demonstrated that deposition of Pt-based NPs resulted in more production of reactive oxygen species including hydroxyl radicals, superoxide, and singlet oxygen. The enhancing effects of Pt-based NPs on generation of ROS and photocatalytic activity showed same trend: PtCuCo > PtCu > Pt. The mechanism underlying the enhancement differences in Pt-based NPs may be mainly related to electronic structure change of Pt in alloying with Cu and Co. These results are valuable for designing hybrid nanomaterials with high photocatalytic efficiency for applications in water purification and antibacterial products.

One-pot synthesis of Schiff base compounds via photocatalytic reaction in the coupled system of aromatic alcohols and nitrobenzene using CdIn2S4 photocatalyst

The use of solar energy to drive organic reactions under mild conditions provides a sustainable pathway for green synthesis and has been one of the primary goals pursued by scientists. In this research, the cadmium indium sulfide (CdIn2S4) photocatalyst was prepared using a simple solvothermal method and was thoroughly characterized using X-ray powder diffraction, UV-visible absorption spectra, nitrogen adsorption-desorption isotherms, scanning electron microscopy, transmission electron microscopy and X-ray spectroscopy measurements. The photocatalytic performance of the CdIn2S4 photocatalyst was evaluated using photocatalytic synthesis of Schiff base compounds in a coupled system of aromatic alcohols and nitrobenzene under visible light irradiation. The yield of N-benzylideneaniline reached up to 32% in the coupled system of benzyl alcohol and nitrobenzene under visible light illumination for 8 h. Furthermore, the changes for the amounts of aromatic aldehydes and AL as intermediate products during the photocatalytic process were also investigated. Using isotopic tracing, a possible reaction mechanism for the photocatalytic synthesis of N-benzylideneaniline and the redox reactions in the coupled system of benzyl alcohol and nitrobenzene was proposed. It is hoped that this strategy can provide an effective pathway for the traditional organic synthesis and transformation using photocatalytic technology under mild conditions.

Hierarchical CdIn2S4 microspheres wrapped by mesoporous g-C3N4 ultrathin nanosheets with enhanced visible light driven photocatalytic reduction activity

In this investigation, a series of hierarchical CdIn₂S₄/g-C₃N₄ nanocomposites were firstly synthesized by a facile one-pot hydrothermal strategy, wherein the mesoporous g-C₃N₄ nanosheets were in-situ self-wrapped onto CdIn₂S₄ nanosheets. Systematic characterization by XRD, FT-IR, UV-vis DRS, SEM, TEM, HAAF-STEM, XPS, photoelectrochemical tests were employed to analyze the phase structure, chemical composition, morphology and photocatalytic mechanism. The application, including photo-redox reaction and photocatalytic water splitting, were used to estimate the photocatalytic activity of as-obtained CdIn₂S₄/g-C₃N₄ nanocomposites. The results indicate that CdIn₂S₄/g-C₃N₄ heterostructures exhibit more efficient improvement of the photocatalytic performances towards photo-reduction of 4-NA to corresponding 4-PDA and photocatalytic H₂ generation from water splitting than these counterparts as results of construction of intimate interfacial contact, which would promote the separation of photo-generated holes and electrons. Meanwhile, benefitting from the excellent surface wrap, the CdIn₂S₄/g-C₃N₄ nanocomposites possess notable enhanced photocatalytic stability. This research may provide a promising way to fabricate highly efficient photocatalysts with excellent stability and expand the application of CdIn₂S₄ in fine chemical engineering.

Transfer Charge and Energy of Ag@CdSe QDs-rGO Core-Shell Plasmonic Photocatalyst for Enhanced Visible Light Photocatalytic Activity

Plasmonic heteronanostructures in semiconductor type display extraordinary photocatalytic efficiency induced by the plasmonic energy that operates in the Ag@CdSe-rGO hybrid ternary composites. The obtained plasmonic photocatalysts in nanoscale were fabricated by using a one-step hydrothermal method, during which the in situ nucleation of Ag@CdSe core-shell nanoparticles and the reduction of GO to rGO occurred simultaneously. Three different roles of Ag core and the junction of synergistic properties arising from the introduced rGO jointly enhanced the optical properties of CdSe. Localized plasmon resonance (LPR) effects of plasmonic Ag contribute to the separation of photogenerated e(-)/h(+) pairs via the electrons and resonant energy transfer. Electrochemical investigations have further confirmed the enhanced separation of the photogenerated e(-)/h(+) pairs. From comparative photocatalytic experiments of Ag@CdSe-rGO and Ag/CdSe-rGO, the plasmonic effect of the Ag core in the Ag@CdSe-rGO nanostructure serves to prolong the charge separation under visible light beyond common attached trimers.