Q-sized cadmium sulfide: synthesis, characterization, and efficiency of photoinitiation of polymerization of several vinylic monomers

Structurally and surficially activated TiO2 nanomaterials for photochemical reactions

Renewable fuels and environmental remediation are of paramount importance in today's world due to escalating concerns about climate change, pollution, and the finite nature of fossil fuels. Transitioning to sustainable energy sources and addressing environmental pollution has become an urgent necessity. Photocatalysis, particularly harnessing solar energy to drive chemical reactions for environmental remediation and clean fuel production, holds significant promise among emerging technologies. As a benchmark semiconductor in photocatalysis, TiO2 photocatalyst offers an excellent solution for environmental remediation and serves as a key tool in energy conversion and chemical synthesis. Despite its status as the default photocatalyst, TiO2 suffers from drawbacks such as a high recombination rate of charge carriers, low electrical conductivity, and limited absorption in the visible light spectrum. This review provides an in-depth exploration of the fundamental principles of photocatalytic reactions and presents recent advancements in the development of TiO2 photocatalysts. It specifically focuses on strategic approaches aimed at enhancing the performance of TiO2 photocatalysts, including improving visible light absorption for efficient solar energy harvesting, enhancing charge separation and transportation efficiency, and ensuring stability for robust photocatalysis. Additionally, the review delves into the application of photodegradation and photocatalysis, particularly in critical processes such as water splitting, carbon dioxide reduction, nitrogen fixation, hydrogen peroxide generation, and alcohol oxidation. It also highlights the novel use of TiO2 in plastic polymerization and degradation, showcasing its potential for converting plastic waste into valuable chemicals and fuels, thereby offering sustainable waste management solutions. By addressing these essential areas, the review offers valuable insights into the potential of TiO2 photocatalysis for addressing pressing environmental and energy challenges. Furthermore, the review encompasses the application of TiO2 photochromic systems, expanding its scope to include other innovative research and applications. Finally, it addresses the underlying challenges and provides perspectives on the future development of TiO2 photocatalysts. Through addressing these issues and implementing innovative strategies, TiO2 photocatalysis can continue to evolve and play a pivotal role in sustainable energy and environmental applications.

Ag-In-Zn-S alloyed nanocrystals as photocatalysts of controlled light-mediated radical polymerization

We report on the first case of the use of nonstoichiometric ternary (Ag-In-Zn-S) semiconductor nanocrystals as photoinitiators and photocatalysts of methyl methacrylate (MMA) polymerization. Two types of nanocrystals were tested, differing in their composition and characterized by red (λmax = 731 nm) and green (λmax = 528 nm) photoluminescence, respectively. Exploiting their reducing properties and capability of free radical generation we demonstrate that under ultraviolet (UV) radiation they effectively photoinitiate radical polymerization of MMA whereas under visible light (blue or green) they act as photocatalysts of living radical polymerization.

One-Step Photochemical Preparation of CdS/Poly(MMA-co-MAA) Composite with Enhanced Photocatalytic Activity

This paper presents a one-step photochemical method for the preparation of CdS/Poly(MMA-co-MAA) composite photocatalyst, based on the concept of simultaneous photocatalytic polymerization of organic monomers during UV-light induced formation of CdS. The preparation is carried out in an aqueous solution of Na2S2O3, CdSO4, methyl methacrylate (MMA) and methacrylic acid (MAA), under a UV lamp. The continuously formed CdS particles with photocatalytic activity act the role of initiator to directly initiate the copolymerization of MMA and MAA, resulting in the in situ formation of the composite and full contact of the CdS particles with the oxygen-containing groups in the polymer. Taking the photocatalytic degradation of methylene blue as a case study, the composite exhibited significantly higher activity under simulated solar light compared to the pure CdS. By analysis on various data, the enhanced photocatalytic activity is attributed to the enhanced visible light absorption, and especially the high electron-hole separation efficiency caused by the electrostatic interaction between photogenerated holes and carbonyl oxygen atoms with negatively charged features. Furthermore, the composite displays excellent sunlight activity and recyclability, suggesting its potential for practical applications. Such a one-step construction strategy relying only on photo-energy is green, low-cost and promising in obtaining high-performance semiconductor/polymer composite photocatalysts.

ZnO Quantum Photoinitiators as an All-in-One Solution for Multifunctional Photopolymer Nanocomposites

Nanocomposites are constructed from a matrix material combined with dispersed nanosized filler particles. Such a combination yields a powerful ability to tailor the desired mechanical, optical, electrical, thermodynamic, and antimicrobial material properties. Colloidal semiconductor nanocrystals (SCNCs) are exciting potential fillers, as they display size-, shape-, and composition-controlled properties and are easily embedded in diverse matrices. Here we present their role as quantum photoinitiators (QPIs) in acrylate-based polymer, where they act as a catalytic radical initiator and endow the system with mechanical, photocatalytic, and antimicrobial properties. By utilizing ZnO nanorods (NRs) as QPIs, we were able to increase the tensile strength and elongation at break of poly(ethylene glycol) diacrylate (PEGDA) hydrogels by up to 85%, unlike the use of the same ZnO NRs acting merely as fillers. Simultaneously, we endowed the PEGDA hydrogels with post-polymerization photocatalytic and antimicrobial activities and showed their ability to decompose methylene blue and significantly eradicate antibiotic-resistant bacteria and viral pathogens. Moreover, we demonstrate two fabrication showcase methods, traditional molding and digital light processing printing, that can yield hydrogels with complex architectures. These results position SCNC-based systems as promising candidates to act as all-in-one photoinitiators and fillers in nanocomposites for diverse biomedical applications, where specific and purpose-oriented characteristics are required.

Metal organic framework-derived transition metal-doped CoSx nanocage for enhanced visible light-assisted methanol electrocatalytic oxidation

Designing noble metal-free anode catalysts for visible light-assisted direct methanol fuel cells still remains a significant challenge. In this study, combining the photocatalytic and electrocatalytic properties of CoSx, a visible light-assisted methanol electrocatalytic oxidation strategy was provided. Doping engineering was employed to adjust the electronic structure of CoSx and improve their photoassisted methanol electrocatalytic oxidation activity. Using ZIF-67 as precursor, transition metal-doped CoSx (M-CoSx, M = Zn, Cu, Ni, and Cd) nanocage was synthesized by cation exchange and L-cysteine-controlled etching. Cd doping not only widens the light adsorption to the visible region but also enhances the separation efficiency of photogenerated electron-hole pairs. The electrochemical and photochemical results indicated that the strong oxidative photogenerated hole, OH˙, and O2˙- are beneficial for methanol electrocatalytic oxidation. The synergistic electrocatalytic and photocatalytic effect will be a practical strategy for improving the methanol electrocatalytic oxidation activity of noble metal-free semiconductor catalysts.

Effect of the TiO2 Colloidal Size Distribution on the Degradation of Methylene Blue

TiO₂ is the most commonly used photocatalyst in water treatment. The particle size of TiO₂ is an important factor that significantly influences its activity during photocatalytic degradation. In the presence of liquid, the properties of nanopowders composed of exactly the same product clearly differ according to their aggregation size. In this study, TiO₂ nanoparticles with a controlled size were fabricated by focused ultrasound dispersion. The high energy generated by this system was used to control the size of TiO₂ particles in the suspension. The constant high energy released by cavitation enabled the dispersion of the particles without a surfactant. The activities of the prepared TiO₂ photocatalysts for methylene blue (MB) degradation were then compared. The dye degradation effect of the photocatalyst was as high as 61.7% after 10 min when the size of the powder was controlled in the solution, but it was only as high as 41.0% when the aggregation size was not controlled. Furthermore, when the TiO₂ concentration exceeded a certain level, the photocatalytic activity of TiO₂ decreased. Controlling the size of the aggregated photocatalyst particles is, therefore, essential in water-treatment technologies utilizing TiO₂ photocatalytic properties, and adjusting the TiO₂ concentration is an important economic factor in this photocatalytic technology. This study contributes to the development of processes for degrading dyes, such as MB, released from wastewater into aquatic environments.

Synthesis Metal-Organic Framework (MOFs) Cr-PTC-HIna Modulated Isonicotinic Acid for Methylene Blue Photocatalytic Degradation

A novel responsive visible light Cr-based MOF, Cr-PTC-HIna, was synthesized using the solvothermal method. Cr-PTC-HIna peaks were observed at 2θ = 9.04°, 12.71°, 14.88°, 25,48°, 27.72°, 28.97°, and 43.60° with a crystal size of 21 nm. Band gap energy achieved from the Cr-PTC HIna was 2.05 eV. Scanning Electron Microscope (SEM) analysis obtained a 3D structural morphology of MOFs Cr-PTC-HIna with a cylindrical tube shape and a particle size of 251.45 nm. Cr-PTC-HIna gave the optimum methylene blue degradation at pH of 7 under 250 watts mercury lamp irradiation for 180 minutes with degradation capacity of 95.40 mg/g. Electron holes and hydroxyl radicals were found as the dominant species contributing to methylene blue degradation. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Red Phosphorus: An Up-and-Coming Photocatalyst on the Horizon for Sustainable Energy Development and Environmental Remediation

Photocatalysis is a perennial solution that promises to resolve deep-rooted challenges related to environmental pollution and energy deficit through harvesting the inexhaustible and renewable solar energy. To date, a cornucopia of photocatalytic materials has been investigated with the research wave presently steered by the development of novel, affordable, and effective metal-free semiconductors with fascinating physicochemical and semiconducting characteristics. Coincidentally, the recently emerged red phosphorus (RP) semiconductor finds itself fitting perfectly into this category ascribed to its earth abundant, low-cost, and metal-free nature. More notably, the renowned red allotrope of the phosphorus family is spectacularly bestowed with strengthened optical absorption features, propitious electronic band configuration, and ease of functionalization and modification as well as high stability. Comprehensively detailing RP's roles and implications in photocatalysis, this review article will first include information on different RP allotropes and their chemical structures, followed by the meticulous scrutiny of their physicochemical and semiconducting properties such as electronic band structure, optical absorption features, and charge carrier dynamics. Besides that, state-of-the-art synthesis strategies for developing various RP allotropes and RP-based photocatalytic systems will also be outlined. In addition, modification or functionalization of RP with other semiconductors for promoting effective photocatalytic applications will be discussed to assess its versatility and feasibility as a high-performing photocatalytic system. Lastly, the challenges facing RP photocatalysts and future research directions will be included to propel the feasible development of RP-based systems with considerably augmented photocatalytic efficiency. This review article aspires to facilitate the rational development of multifunctional RP-based photocatalytic systems by widening the cognizance of rational engineering as well as to fine-tune the electronic, optical, and charge carrier properties of RP.

Computational approach to (ZnS)_{i} nanoclusters in ionic liquids

Unique and attractive properties have been predicted for II-VI-type semiconductor nanoclusters within the field of nanotechnology. However, the low reaction kinetics within the usual solvents gives only thermodynamic control during their production process, making the obtention of different metastable polymorphs extremely difficult. The use of ionic liquids as solvents has been proposed to overcome this problem. Identifying how these nanoclusters are solvated within ionic liquids is fundamental if this strategy is to be pursued. While computational chemistry tools are best suited for this task, the complexity and size of the system requires a careful design of the simulation protocol, which is put forward in this work. Taking as reference the (ZnS)_{12} nanocluster and the [EMIM][EtSO_{4}] ionic liquid, we characterize the interactions between the nanoparticle and first solvation shell by density functional theory calculations, considering most of the solvent implicitly. The DFT results are consistent through different theory levels showing a strong interaction between the Zn atoms of the nanocluster and the [EtSO_{4}^{-}] anion of the ionic liquid. A more realistic representation of the system is obtained by classical MD calculations, for which various classical force fields were considered and several atomic interactions parameterized. This new set of parameters correctly describes the interaction of different (ZnS) nanoclusters, supporting its transferability. The resulting MD simulation shows the formation of a structured ionic liquid solvation shell around the nanocluster with no exchange of ions for at least 5 ns, in agreement with the strong interactions observed in the density functional theory calculations.

Light-Mediated Polymerization Induced by Semiconducting Nanomaterials: State-of-the-Art and Future Perspectives

Direct capture of solar energy for chemical transformation via photocatalysis proves to be a cost-effective and energy-saving approach to construct organic compounds. With the recent growth in photosynthesis, photopolymerization has been established as a robust strategy for the production of specialty polymers with complex structures, precise molecular weight, and narrow dispersity. A key challenge in photopolymerization is the scarcity of effective photomediators (photoinitiators, photocatalysts, etc.) that can provide polymerization with high yield and well-defined polymer products. Current efforts on developing photomediators have mainly focused on organic dyes and metal complexes. On the other hand, nanomaterials (NMs), particularly semiconducting nanomaterials (SNMs), are suitable candidates for photochemical reactions due to their unique optical and electrical properties, such as high absorption coefficients, large charge diffusion lengths, and broad absorption spectra. This review provides a comprehensive insight into SNMs' photomediated polymerizations and highlights the roles SNMs play in photopolymerizations, types of polymerizations, applications in producing advanced materials, and the future directions.

Quantum Photoinitiators: Toward Emerging Photocuring Applications

Semiconductor nanocrystals are promising photocatalysts for a wide range of applications, ranging from alternative fuel generation to biomedical and environmental applications. This stems from their diverse properties, including flexible spectral tunability, stability, and photocatalytic efficiencies. Their functionality depends on the complex influence of multiple parameters, including their composition, dimensions, architecture, surface coating, and environmental conditions. A particularly promising direction for rapid adoption of these nanoparticles as photocatalysts is their ability to act as photoinitiators (PIs) for radical polymerization. Previous studies served to demonstrate the proof of concept for the use of quantum confined semiconductor nanocrystals as photoinitiators, coining the term Quantum PIs, and provided insights for their photocatalytic mechanism of action. However, these early reports suffered from low efficiencies while requiring purging with inert gases, use of additives, and irradiation by high light intensities with very long excitation durations, which limited their potential for real-life applications. The progress in nanocrystal syntheses and surface engineering has opened the way to the introduction of the next generation of Quantum PIs. Herein, we introduce the research area of nanocrystal photocatalysts, review their studies as Quantum PIs for radical polymerization, from suspension polymerization to novel printing, as well as in a new family of polymerization techniques, of reversible deactivation radical polymerization, and provide a forward-looking view for the challenges and prospects of this field.

Thiol ligand capped quantum dot as an efficient and oxygen tolerance photoinitiator for aqueous phase radical polymerization and 3D printing under visible light

We report here a rapid visible-light-induced radical polymerization in aqueous media photoinitiated by only ppm level thiol ligand capped cadmium selenide quantum dots. The photoinitiation system could be readily employed for photo 3D printing.

Heterogeneous photocatalytic reversible deactivation radical polymerization

Photocatalytic reversible deactivation radical polymerization (RDRP) permits the use of sustainable solar light for spatiotemporal regulation of radical polymerization under mild conditions.

Role of External Field in Polymerization: Mechanism and Kinetics

The past decades have witnessed an increasing interest in developing advanced polymerization techniques subjected to external fields. Various physical modulations, such as temperature, light, electricity, magnetic field, ultrasound, and microwave irradiation, are noninvasive means, having superb but distinct abilities to regulate polymerizations in terms of process intensification and spatial and temporal controls. Gas as an emerging regulator plays a distinctive role in controlling polymerization and resembles a physical regulator in some cases. This review provides a systematic overview of seven types of external-field-regulated polymerizations, ranging from chain-growth to step-growth polymerization. A detailed account of the relevant mechanism and kinetics is provided to better understand the role of each external field in polymerization. In addition, given the crucial role of modeling and simulation in mechanisms and kinetics investigation, an overview of model construction and typical numerical methods used in this field as well as highlights of the interaction between experiment and simulation toward kinetics in the existing systems are given. At the end, limitations and future perspectives for this field are critically discussed. This state-of-the-art research progress not only provides the fundamental principles underlying external-field-regulated polymerizations but also stimulates new development of advanced polymerization methods.

Recent advances in metal sulfides: from controlled fabrication to electrocatalytic, photocatalytic and photoelectrochemical water splitting and beyond

This review describes an in-depth overview and knowledge on the variety of synthetic strategies for forming metal sulfides and their potential use to achieve effective hydrogen generation and beyond.

Improving photocatalytic free radical polymerization with hydrochloric acid

Improving photocatalytic free radical polymerization of vinyl acetate with hydrochloric acid.

Surfactant assisted self-assembly of Ag+ containing nanocrystals and their facet dependent photocatalytic activity

This work demonstrates a general route for synthesis of nanocatalysts containing silver ions using surfactants.

Strategies to synthesize various nanostructures of silver and their applications - a review

Due to their various beneficial application-based properties, such as behavior, structure, and size, the synthesis of silver nanoparticles (Ag-NPs) with different structures has become an interesting yet common task for researchers to produce nanostructures for applications in various fields. This is because silver nanoparticles have interesting and unique properties, such as optical and catalytic, resulting from their different structures and sizes. These properties extend the use of nanostructures in various fields of research, especially in medicine, pharmacy, electronics, etc. Also, variations in their parameters affect the structures and sizes of Ag-NPs. This review provides an overview/brief presentation of various methodologies used to synthesize different application-based silver nanoparticles and lists areas where these nanoparticles are suitable for use according to their specific structures and sizes.

Semiconductor Quantum Dots as Photocatalysts for Controlled Light-Mediated Radical Polymerization

Light-mediated radical polymerization has benefited from the rapid development of photoredox catalysts and offers many exceptional advantages over traditional thermal polymerizations. Nevertheless, the majority of the work relies on molecular photoredox catalysts or expensive transition metals. We exploited the capability of semiconductor quantum dots (QD) as a new type of catalyst for the radical polymerization that can harness natural sunlight. Polymerizations of (meth)acrylates, styrene, and construction of block copolymers were demonstrated, together with temporal control of the polymerization by the light source. Photoluminescence experiments revealed that the reduction of alkyl bromide initiator by photoexcited QD is the key to this light-mediated radical polymerization.

Photocatalysis in organic and polymer synthesis

This review, with over 600 references, summarizes the recent applications of photoredox catalysis for organic transformation and polymer synthesis. Photoredox catalysts are metallo- or organo-compounds capable of absorbing visible light, resulting in an excited state species. This excited state species can donate or accept an electron from other substrates to mediate redox reactions at ambient temperature with high atom efficiency. These catalysts have been successfully implemented for the discovery of novel organic reactions and synthesis of added-value chemicals with an excellent control of selectivity and stereo-regularity. More recently, such catalysts have been implemented by polymer chemists to post-modify polymers in high yields, as well as to effectively catalyze reversible deactivation radical polymerizations and living polymerizations. These catalysts create new approaches for advanced organic transformation and polymer synthesis. The objective of this review is to give an overview of this emerging field to organic and polymer chemists as well as materials scientists.

The fabrication of CdS/CoFe2O4/rGO photocatalysts to improve the photocatalytic degradation performance under visible light

A magnetic photocatalyst, CdS/CoFe₂O₄/rGO, has been successfully prepared via a simple hydrothermal method. The photocatalytic activity of the as-obtained composite photocatalyst was evaluated using the degradation of tetracycline.

Electronic Processes within Quantum Dot-Molecule Complexes

The subject of this review is the colloidal quantum dot (QD) and specifically the interaction of the QD with proximate molecules. It covers various functions of these molecules, including (i) ligands for the QDs, coupled electronically or vibrationally to localized surface states or to the delocalized states of the QD core, (ii) energy or electron donors or acceptors for the QDs, and (iii) structural components of QD assemblies that dictate QD-QD or QD-molecule interactions. Research on interactions of ligands with colloidal QDs has revealed that ligands determine not only the excited state dynamics of the QD but also, in some cases, its ground state electronic structure. Specifically, the article discusses (i) measurement of the electronic structure of colloidal QDs and the influence of their surface chemistry, in particular, dipolar ligands and exciton-delocalizing ligands, on their electronic energies; (ii) the role of molecules in interfacial electron and energy transfer processes involving QDs, including electron-to-vibrational energy transfer and the use of the ligand shell of a QD as a semipermeable membrane that gates its redox activity; and (iii) a particular application of colloidal QDs, photoredox catalysis, which exploits the combination of the electronic structure of the QD core and the chemistry at its surface to use the energy of the QD excited state to drive chemical reactions.

CdS-graphene Nanocomposite for Efficient Visible-light-driven Photocatalytic and Photoelectrochemical Applications

This paper reports cadmium sulphide nanoparticles-(CdS NPs)-graphene nanocomposite (CdS-Graphene), prepared by a simple method, in which CdS NPs were anchored/decorated successfully onto graphene sheets. The as-synthesized nanocomposite was characterized using standard characterization techniques. A combination of CdS NPs with the optimal amount of two-dimensional graphene sheets had a profound influence on the properties of the resulting hybrid nanocomposite, such as enhanced optical, photocatalytic, and photo-electronic properties. The photocatalytic degradation ability of the CdS-Graphene nanocomposite was evaluated by degrading different types of dyes in the dark and under visible light irradiation. Furthermore, the photoelectrode performance of the nanocomposite was evaluated by different electrochemical techniques. The results showed that the CdS-Graphene nanocomposite can serve as an efficient visible-light-driven photocatalyst as well as photoelectrochemical performance for optoelectronic applications. The significantly enhanced photocatalytic and photoelectrochemical performance of the CdS-Graphene nanocomposite was attributed to the synergistic effects of the enhanced light absorption behaviour and high electron conductivity of the CdS NPs and graphene sheets, which facilitates charge separation and lengthens the lifetime of photogenerated electron-hole pairs by reducing the recombination rate. The as-synthesized narrow band gap CdS-Graphene nanocomposite can be used for wide range of visible light-induced photocatalytic and photoelectrochemical based applications.

Photocatalytic Conversion of Nitrobenzene to Aniline through Sequential Proton-Coupled One-Electron Transfers from a Cadmium Sulfide Quantum Dot

This paper describes the use of cadmium sulfide quantum dots (CdS QDs) as visible-light photocatalysts for the reduction of nitrobenzene to aniline through six sequential photoinduced, proton-coupled electron transfers. At pH 3.6-4.3, the internal quantum yield of photons-to-reducing electrons is 37.1% over 54 h of illumination, with no apparent decrease in catalyst activity. Monitoring of the QD exciton by transient absorption reveals that, for each step in the catalytic cycle, the sacrificial reductant, 3-mercaptopropionic acid, scavenges the excitonic hole in ∼5 ps to form QD(•-); electron transfer to nitrobenzene or the intermediates nitrosobenzene and phenylhydroxylamine then occurs on the nanosecond time scale. The rate constants for the single-electron transfer reactions are correlated with the driving forces for the corresponding proton-coupled electron transfers. This result suggests, but does not prove, that electron transfer, not proton transfer, is rate-limiting for these reactions. Nuclear magnetic resonance analysis of the QD-molecule systems shows that the photoproduct aniline, left unprotonated, serves as a poison for the QD catalyst by adsorbing to its surface. Performing the reaction at an acidic pH not only encourages aniline to desorb but also increases the probability of protonated intermediates; the latter effect probably ensures that recruitment of protons is not rate-limiting.

Photocatalytic Surface-Initiated Polymerization on TiO2 toward Well-Defined Composite Nanostructures

We demonstrate the use of TiO2 nanospheres as the photoinitiator for photocatalytic surface-initiated polymerization for the synthesis of various inorganic/polymer nanocomposites with well-defined structures. The excitation of TiO2 by UV-light irradiation produces electrons and holes which drive the free radical polymerization near its surface, producing core/shell composite nanospheres with eccentric or concentric structures that can be tuned by controlling the surface compatibility between the polymer and the TiO2. When highly porous TiO2 nanospheres were employed as the photoinitiator, polymerization could disintegrate the mesoporous framework and give rise to nanocomposites with multiple TiO2 nanoparticles evenly distributed in the polymer spheres. Thanks to the well-developed sol-gel chemistry of titania, this synthesis is well-extendable to the coating of the polymers on many other substrates of interest such as silica and ZnS by simply premodifying their surface with a thin layer of titania. In addition, this strategy could be easily applied to coating of different types of polymers such as polystyrene, poly(methyl methacrylate), and poly(N-isopropylacrylamide). We expect this photocatalytic surface-initiated polymerization process could provide a platform for the synthesis of various inorganic/polymer hybrid nanocomposites for many interesting applications.

Photoinduced Electron Transfer Reactions for Macromolecular Syntheses

Photochemical reactions, particularly those involving photoinduced electron transfer processes, establish a substantial contribution to the modern synthetic chemistry, and the polymer community has been increasingly interested in exploiting and developing novel photochemical strategies. These reactions are efficiently utilized in almost every aspect of macromolecular architecture synthesis, involving initiation, control of the reaction kinetics and molecular structures, functionalization, and decoration, etc. Merging with polymerization techniques, photochemistry has opened up new intriguing and powerful avenues for macromolecular synthesis. Construction of various polymers with incredibly complex structures and specific control over the chain topology, as well as providing the opportunity to manipulate the reaction course through spatiotemporal control, are one of the unique abilities of such photochemical reactions. This review paper provides a comprehensive account of the fundamentals and applications of photoinduced electron transfer reactions in polymer synthesis. Besides traditional photopolymerization methods, namely free radical and cationic polymerizations, step-growth polymerizations involving electron transfer processes are included. In addition, controlled radical polymerization and "Click Chemistry" methods have significantly evolved over the last few decades allowing access to narrow molecular weight distributions, efficient regulation of the molecular weight and the monomer sequence and incredibly complex architectures, and polymer modifications and surface patterning are covered. Potential applications including synthesis of block and graft copolymers, polymer-metal nanocomposites, various hybrid materials and bioconjugates, and sequence defined polymers through photoinduced electron transfer reactions are also investigated in detail.

A metal sulfide photocatalyst composed of ubiquitous elements for solar hydrogen production

A visible-light-sensitive tin sulfide photocatalyst was designed based on a ubiquitous element strategy and density functional theory (DFT) calculations.

Synthesis and testing of ZnO nanoparticles for photo-initiation: experimental observation of two different non-migration initiators for bulk polymerization

The migration and transport of polymerization initiators are problematic for commercially used polymerization procedures. For example, UV printing of packaging generates products with potentially harmful components that come in contact with food. Enlarging the size of the initiator is the only way to prevent contamination, e.g., by gas phase transport. In this manuscript, the synthesis and advanced and full analyses of novel nanoparticle-based types of non-migration, fragmenting and non-fragmenting photo-initiators will be presented in detail. This study introduces non-fragmenting/"Norrish type II" and fragmenting/"Norrish type I" ZnO nanoparticle-based initiators and compares them with two commercial products, a "Norrish type I" initiator and a "Norrish type II" initiator. Therefore, inter alia, the recently developed analysis involves examining the solidification by UV-vis and the double bond content by Raman. Irradiation is performed using absolute and spectrally calibrated xenon flash lights. A novel procedure for absolute and spectral calibration of such light sources is also presented. The non-optimized "Norrish type II" particle-based initiator is already many times faster than benzophenone, which is a molecular initiator of the same non-fragmenting type. This experimentally observed difference in reactive particle-based systems without co-initiators is unexpected. Co-initiators are normally an additional molecular species, which leads to migration problems. The discovery of significant initiation potential resulting in a very well-dispersed organic-inorganic hybrid material suggests a new field of research opportunities at the interface of physical chemistry, polymer chemistry and engineering science, with enormous value for human health.

Green Synthesis of Silver Nanoparticle Using Banana (Musa) Sap

Green synthesis of silver nanoparticles using banana sap as a solvent, reducing agent and capping agent is reported in this work. Banana sap has also been used as a binder to incorporate silver nanoparticles into cotton fabric. UV-Visible spectroscopy was used to monitor the quantitative formation of silver nanoparticles. Silver nanoparticle coated fabric showed high antimicrobial activity against gram negative bacteria such asPseudomonas aureginosaandEscherichia coli, and gram positive bacteria such asBacillus subtilisandStaphylococcus aureus.KeywordsGreen synthesis, Silver nanoparticles, banana sap, antimicrobial activity

Method to analyse energy and intensity dependent photo-curing of acrylic esters in bulk

The photo-polymerizations induced by three different model resins, containing well-known commercial initiators, are monitored by an in situ Raman UV-vis system and analysed in detail.

Magnetic iron oxide nanoparticles as long wavelength photoinitiators for free radical polymerization

Iron oxide nanoparticles (Fe₃O₄ NPs) capped with lauric acid agents were synthesized and their photocatalytic activity was investigated in free radical photopolymerization of vinyl monomers.