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Photoactive artificial nanocatalysts that mimic natural photoenergy systems can yield clean and renewable energy. However, their poor photoabsorption capability and disfavored photogenic electron–hole recombination hinder their production. Herein, we designed two nanocatalysts with various microstructures by combining the tailored self-assembly of the meso-tetra(p-hydroxyphenyl) porphine photosensitizer with the growth of titanium dioxide (TiO2). The porphyrin photoabsorption antenna efficiently extended the absorption range of TiO2 in the visible region, while anatase TiO2 promoted the efficient electron–hole separation of porphyrin. The photo-induced electrons were transferred to the surface of the Pt co-catalyst for the generation of hydrogen via water splitting, and the hole was utilized for the decomposition of methyl orange dye. The hybrid structure showed greatly increased photocatalytic performance compared to the core@shell structure due to massive active sites and increased photo-generated electron output. This controlled assembly regulation provides a new approach for the fabrication of advanced, structure-dependent photocatalysts. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) photocatalysts, characterized by exceptional photocatalytic activity, high photoelectric conversion efficiency, and economic viability, have found widespread application in recent years for azo dye degradation. However, inherent constraints, such as the material's limited visible light absorption stemming from its bandgap and the swift recombination of charge carriers, have impeded its broader application potential. Encouragingly, these barriers can be mitigated through the modification of TiO2. In this review, the common synthesis methods of TiO2 are reviewed, and the research progress of TiO2 modification technology at home and abroad is discussed in detail, including precious metal deposition, transition metal doping, rare earth metal doping, composite semiconductors, and composite polymers. These modification techniques effectively enhance the absorption capacity of TiO2 in the visible region and reduce the recombination rate of carriers and electrons, thus significantly improving its photocatalytic performance. Finally, this paper looks forward to the future development direction of TiO2 photocatalytic materials, including the exploration of new modified materials, in-depth mechanism research, and performance optimization in practical applications, to provide useful references for further research and application of TiO2 photocatalytic materials. [ABSTRACT FROM AUTHOR]

In this study, we prepared the SnO2/ZnFe2O4 (SZ) composite magnetic photocatalyst via a two-step hydrothermal method. Structural and performance analyses revealed that SZ-5 with a ZnFe2O4 mass ratio of 5% (SZ-5) exhibited optimal photocatalytic activity, achieving a 72.6% degradation rate of Rhodamine B (RhB) solution within 120 min. SZ-5 consisted of irregular nano blocks of SnO2 combined with spherical nanoparticles of ZnFe2O4, with a saturated magnetization intensity of 1.27 emu/g. Moreover, the specific surface area of SnO2 loaded with ZnFe2O4 increased, resulting in a decreased forbidden bandwidth and expanded light absorption range. The construction of a Z-type heterojunction structure between SnO2 and ZnFe2O4 facilitated the migration of photogenerated charges, reduced the recombination rate of electron-hole pairs, and enhanced electrical conductivity. During the photocatalytic reaction, RhB was degraded by·OH, O2−, and h+, in which O2− played a major role. [ABSTRACT FROM AUTHOR]

Crystalline cerium(III) phosphate (CePO4), cerium(IV) phosphates, and nanocrystalline ceria are considered to be promising components of sunscreen cosmetics. This paper reports on a study in which, for the first time, a quantitative comparative analysis was performed of the UV-shielding properties of CePO4, Ce(PO4)(HPO4)0.5(H2O)0.5, and CePO4/CeO2 composites. Both the sun protection factor and protection factor against UV-A radiation of the materials were determined. Ce(PO4)(HPO4)0.5(H2O)0.5 was shown to have a sun protection factor of 2.9, which is comparable with that of nanocrystalline ceria and three times higher than the sun protection factor of CePO4. Composites containing both cerium dioxide and CePO4 demonstrated higher sun protection factors (up to 1.8) than individual CePO4. When compared with the TiO2 Aeroxide P25 reference sample, cerium(III) and cerium(IV) phosphates demonstrated negligible photocatalytic activity. A cytotoxicity analysis performed using two mammalian cell lines, hMSc and NCTC L929, showed that CePO4, Ce(PO4)(HPO4)0.5(H2O)0.5, and nanocrystalline ceria were all non-toxic. The results of this comparative study indicate that cerium(IV) phosphate Ce(PO4)(HPO4)0.5(H2O)0.5 is more advantageous for use in sunscreens than either cerium(III) phosphate or CePO4/CeO2 composites, due to its improved UV-shielding properties and low photocatalytic activity. [ABSTRACT FROM AUTHOR]

Sonogashira coupling is one of the Nobel reactions discovered in 1975 to form a C–C bond using palladium and copper as co-catalysts. Incorporating alkyne functionalities either in macro or micro molecules by using this Sonogashira reaction has already proven its viability and relevance in the sphere of synthetic chemistry. While aiming for sustainable chemistry, in recent years, visible light photoredox catalysts have appeared as an advanced tool in this regard. In this review, we aim to portray a comprehensive summary of modern visible light photo redox catalyzed Sonogashira reaction, which will leave space for the readers to rethink alternative strategies to conduct the Sonogashira reaction. This review briefly describes the implementation of various metal-based nanomaterial photocatalysts, developing either copper or palladium-free photocatalytic methods, and organo-photolytic and bioinspired photocatalysts for the Sonogashira coupling reactions. Besides, this review also gives a concise overview of the mechanistic aspects and highlights selective examples for substrate scope. [ABSTRACT FROM AUTHOR]

Two series of hybrid inorganic–organic materials, prepared via interlayer organic modification of protonated Ruddlesden–Popper phases HLnTiO4 (Ln = La, Nd) with n-alkylamines and n-alkoxy groups of various lengths, have been systematically studied with respect to photocatalytic hydrogen evolution from aqueous methanol under near-ultraviolet irradiation for the first time. Photocatalytic measurements were organized in such a way as to control a wide range of parameters, including the hydrogen generation rate, quantum efficiency of the reaction, potential dark activity of the sample, its actual volume concentration in the suspension, pH of the medium and stability of the photocatalytic material under the operating conditions. The insertion of the organic modifiers into the interlayer space of the titanates allowed obtaining new, more efficient photocatalytic materials, being up to 68 and 29 times superior in the activity in comparison with the initial unmodified compounds HLnTiO4 and a reference photocatalyst TiO2 P25 Degussa, respectively. The hydrogen evolution rate over the samples correlates with the extent of their interlayer hydration, as in the case of the inorganic–organic derivatives of other layered perovskites reported earlier. However, the HLnTiO4-based samples demonstrate increased stability with regard to the photodegradation of the interlayer organic components as compared with related H2Ln2Ti3O10-based hybrid materials. [ABSTRACT FROM AUTHOR]

In this study, a carboxylated carbon nanotube-grafted Ag3PO4@AgIO4 (CNT-COO−/Ag3PO4@AgIO4) composite was synthesized through an in situ electrostatic deposition method. The synthesized composite was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and energy-dispersive X-ray spectroscopy (EDS). The electron transfer ability of the synthesized composite was studied using electrochemical impedance spectroscopy (EIS). The CNT-COO−/Ag3PO4@AgIO4 composite exhibited higher activity than CNT/Ag3PO4@AgIO4, Ag3PO4@AgIO4, and bare Ag3PO4. The material characterization and the detailed study of the various parameters thataffect the photocatalytic reaction revealed that the enhanced catalytic activity is related to the good interfacial interaction between CNT-COO and Ag3PO4. The energy band structure analysis is further considered as a reason for multi-electron reaction enhancement. The results and discussion in this study provide important information for the use of the functionalized CNT-COOH in the field of photocatalysis. Moreover, providinga new way to functionalize CNT viadifferent functional groups may lead to further development in the field of photocatalysis. This work could provide a new way to use natural sunlight to facilitate the practical application of photocatalysts toenvironmental issues. [ABSTRACT FROM AUTHOR]

The native forest of northwestern Argentina, as part of the Chaco region, is a rich and unexploited source of phytochemical compounds for medicinal/cosmetic applications. In the present study, fruit, leaf, branch, and bark organs of the native trees Sarcomphalus mistol (Mistol, M) and Schinopsis lorentzii (Quebracho Colorado santiagueño, QC) were harvested, and aqueous plant extracts (PE) were prepared. The spectroscopic (UV–Vis absorbance, diffuse reflectance, ATR-FTIR) and antioxidant (TEAC, Folin–Ciocalteu) properties of PE were characterized and used as TiO2 coating material to obtain a series of TiO2@PE nanocomposites. These materials showed almost null photocatalytic activity compared to aqueous suspensions of bare TiO2, displaying yellowish to brownish coloration and high long-term stability in both freshwater and seawater model solutions. The loss of photocatalytic activity in TiO2@PE was associated with the combination of the internal filter effect and the antioxidant/radical capacity exerted by the phytochemicals of the PE coating, with higher broadband photoprotection for the nanocomposites prepared with QC extracts. Thus, this study shows the potential capacity of the forest resources of the Chaco region of Argentina for the development of new cosmetic and/or sun protection formulations. [ABSTRACT FROM AUTHOR]

To date, remarkable progress has been achieved in the development of photocatalysts owing to their high activity, selectivity, and tunable light absorption in the visible light range. Recently, heterogeneous photocatalytic systems have emerged as potential candidates due to their beneficial attributes (e.g., high surface area, ease of functionalization and facile separation). Herein, we provide a concise overview of the rational design of heterogeneous photocatalysts by grafting photoactive complexes on heterogeneous support matrices via covalent grafting and their detailed characterization techniques, which have been followed by the landmark examples of their applications. Also, major challenges and opportunities in the forthcoming progress of these appealing areas are emphasised. [ABSTRACT FROM AUTHOR]

In order to synthesize the zinc-titanium (Zn-Ti) oxide nanocomposites using an atmospheric soft plasma jet, in this study mixtures of Zn and Ti precursors such as zinc nitrate and titanium butoxide were first prepared with different molar ratios; the mixed precursors then stirred at 700 rpm for two hours with atmospheric plasma, while maintaining a temperature of 25 °C. All the synthesized Zn-Ti oxide nanocomposites were post-heat-treated at 600 °C for six hours in an electrical furnace. The morphology, particle shape and size, crystal structure, oxidation state, and composition ratio were analyzed using FE-SEM, XRD, SEM-EDS, and Raman spectroscopy. BET was measured to calculate the specific surface area of the Zn-Ti oxide nanocomposites. Photocatalytic activity tests were performed for an application study, with 10 mL of 10 ppm methylene blue dye. UV-visible spectroscopy was performed on five different samples in order to analyze the changes of photocatalytic reactions. When the composition ratio of Zn/Ti was 2/1, maximum photocatalytic efficiency was obtained. We also carried out a theoretical kinetic study. [ABSTRACT FROM AUTHOR]

Photoreforming is a process that connects the redox capability of photocatalysts upon light illumination to simultaneously drive the reduction of protons into hydrogen and the oxidation of organic substrates. Over the past few decades, researchers have devoted substantial efforts to enhancing the photocatalytic activity of the catalyst in hydrogen production. Currently, the realization of the potential of photocatalysts for simultaneous hydrogen production with value-added organics has motivated the research field to use the photo-oxidation path. As a distinct benefit, the less energetically demanding organic reforming is highly favorable compared to the slow kinetics of oxygen evolution, negating the need for expensive and/or harmful hole scavengers. Photocatalyst modifications, such as secondary component deposition, doping, defect, phase and morphology engineering, have been the main strategies adopted to tune the photo-oxidation pathways and oxidation products. The effect of the reaction parameters, including temperature, pH, reactant concentration and promising reactor strategies, can further enhance selectivity toward desired outcomes. This review provides a critical overview of photocatalysts in hydrogen production, including chemical reactions occurring with semiconductors and co-catalysts. The use of various oxygenates as sacrificial agents for hydrogen production is outlined in view of the transition of fossil fuels to clean energy. This review mainly focuses on recent development in the photoreforming of carboxylic acids, produced from the primary source, lignocellulose, through pyrolysis. The photo-oxidation of different carboxylic acids, e.g., formic acid, acetic acid and lactic acid, over different photocatalysts for hydrogen production is reviewed. [ABSTRACT FROM AUTHOR]

Waste-derived materials obtained from the recovery and recycling of electronic waste (e-waste) such as batteries and printed circuit boards have attracted enormous attention from academia and industry in recent years, especially due to their eco-friendly nature and the massive increment in e-waste due to technological development. Several investigations in the literature have covered the advances achieved so far. Meanwhile, photocatalytic applications are especially of interest since they maintain mutual benefits and can be used for H2 production from solar water splitting based on semiconductor processing as a proper environmentally friendly technique for solar energy conversion. In addition, they can be utilized to degrade a variety of organic and non-organic contaminations. Nonetheless, to the best of the authors' knowledge, there has not been any comprehensive review that has specifically been focused on e-waste-derived photocatalytic materials. In this regard, the present work is dedicated to thoroughly discussing the related mechanisms, strategies, and methods, as well as the various possible photocatalysts synthesized from e-wastes with some critiques in this field. This brief overview can introduce modern technologies and promising possibilities for e-waste valorization, photocatalytic processes, and new photocatalytic degradation methods of eco-friendly nature. This paper discusses various e-waste-obtained photocatalytic materials, synthesis procedures, and applications, as well as several types of e-waste, derived materials such as TiO2, ZnO, indium tin oxide, and a variety of sulfide- and ferrite-based photocatalytic materials. [ABSTRACT FROM AUTHOR]

The current work deals with the fabrication of novel MoO3 nanostructured films with Ce and Cu co-doping through the spray pyrolysis route on a glass substrate maintained at 460 °C for the first time. The phase of developed films was approved by an X-ray diffraction study, and the crystallite size was determined between 82 and 92 nm. The optical transmission of the developed films was noticed to be reduced with doping and found between 45 and 90% for all films, and the absorption edge shifted to a higher wavelength with doping. The optical energy gap of the fabricated films was found to be reduced from 3.85 to 3.28 eV with doping. The developed films were used to degrade the harmful Eosin-Y dye under UV light. The system with 2% Ce and 1% Cu-doped MoO3 turned out to be the most effective catalyst for photodegradation of the dye in a period of 3H and almost degrade it. Hence, the MoO3 films prepared with 2% Ce and 1% Cu will be highly applicable as photocatalysts for the removal of hazardous dye from wastewater. [ABSTRACT FROM AUTHOR]

Aurivillius oxides ferroelectric layered materials are formed by bismuth oxide and pseu-do-perovskite layers. They have a good ionic conductivity, which is beneficial for various photo-catalyzed reactions. Here, we synthesized ultra-thin nanosheets of two different Aurivillius oxides, Bi2WO6 (BWO) and Bi2MoO6 (BMO), by using a hard-template process. All materials were characterized through XRD, TEM, FTIR, TGA/DSC, DLS/ELS, DRS, UV-Vis. Band gap material (Eg) and potential of the valence band (EVB) were calculated for BWO and BMO. In contrast to previous reports on the use of multi composite materials, a new procedure for photocatalytic efficient BMO nanosheets was developed. The procedure, with an additional step only, avoids the use of composite materials, improves crystal structure, and strongly reduces impurities. BWO and BMO were used as photocatalysts for the degradation of the water pollutant dye malachite green (MG). MG removal kinetics was fitted with Langmuir—Hinshelwood model obtaining a kinetic constant k = 7.81 × 10−2 min−1 for BWO and k = 9.27 × 10−2 min−1 for BMO. Photocatalytic dye degradation was highly effective, reaching 89% and 91% MG removal for BWO and BMO, respectively. A control experiment, carried out in the absence of light, allowed to quantify the contribution of adsorption to MG removal process. Adsorption contributed to MG removal by a 51% for BWO and only by a 19% for BMO, suggesting a different degradation mechanism for the two photocatalysts. The advanced MG degradation process due to BMO is likely caused by the high crystallinity of the material synthetized with the new procedure. Reuse tests demonstrated that both photocatalysts are highly active and stable reaching a MG removal up to 95% at the 10th reaction cycle. These results demonstrate that BMO nanosheets, synthesized with an easy additional step, achieved the best degradation performance, and can be successfully used for environmental remediation applications. [ABSTRACT FROM AUTHOR]

This review article gives an update on the metal‐free photocatalyzed and photocatalyzed‐free α‐C−H functionalizations of tertiary amines promoted by visible light. C−H activation is one of the easiest and step‐economic strategies to functionalize the α‐C−H bond of tertiary amines. Various important nitrogen heterocycles having biological significance can be synthesized using α‐C−H functionalization of tertiary amines. In addition to thermal reactions, many such reactions have been reported using visible light as it is abundant, renewable and green alternative for organic transformations. However, the high price of transition metal photocatalyst prevents its use. In contrast, organic photocatalysts are inexpensive, environment friendly and easy to handle. Therefore, visible‐light‐promoted metal‐free photoredox catalysis (or photocatalyst‐free reactions) is being used recently. Although several research articles have been published in this area, no review articles have been reported recently. Here, we have discussed the reactions from the year 2011 to till date with concise discussion about their plausible mechanisms. We believe that the content of this review will guide the readers to develop more such visible‐light‐promoted reactions using metal‐free photocatalysts or avoiding catalysts if possible. [ABSTRACT FROM AUTHOR]

A new photocatalytic ring expansion reaction that transforms γ‐lactams into 2‐pyridones is described. The reaction is radical‐triggered and was inspired by a late‐stage oxidation commonly observed in fungal metabolism. The reaction is particularly powerful because it can be included in a one pot process which converts readily accessible furans directly into 2‐pyridones through sequential photo‐induced reactions (energy transfer and electron transfer). The study also unveiled unprecedented reactivity for the mild and metal‐free photocatalyst eosin, wherein it is used to cleave a C−I bond activated only by an electron donor on the neighbouring carbon. [ABSTRACT FROM AUTHOR]

Reduction-and-oxidation (redox) reactions are one of the most utilized approaches for the synthesis of value-added compounds. With the growing awareness of green chemistry, researchers have searched for new and sustainable pathways for performing redox reactions. From this, a new field has gained tremendous attention, namely photoredox catalysis. Here, molecules can be easily oxidized or reduced with the use of one of Nature's biggest resources: visible light. This tutorial paper gives the basics of photoredox catalysis along with limited examples to encourage further research in this blooming research area. 1 Introduction 2 Redox Chemistry 3 Photochemistry 3.1 Laws of Photochemistry 3.2 Principles 3.3 Examples 4 Photoredox Catalysis 4.1 General Principles 4.2 Classification of Redox Processes 4.3 Other Mechanistic Considerations 4.4 Stern–Volmer Plots 4.5 Photophysical Properties 4.6 Redox Potentials 5 Photocatalysts 5.1 Metal-Based Photocatalysts 5.2 Organic Dyes 5.3 Semiconductors 6 Dual Catalysis 7 Conclusions [ABSTRACT FROM AUTHOR]

Photocatalytic air purification is widely regarded as a promising technology, but it calls for more efficient photocatalytic materials and systems. Here we report a strategy to introduce an in-situ water (self-wetting) layer on WO3 by coating hygroscopic periodic acid (PA) to dramatically enhance the photocatalytic removal of hydrophilic volatile organic compounds (VOCs) in air. In ambient air, water vapor is condensed on WO3 to make a unique tri-phasic (air/water/WO3) system. The in-situ formed water layer selectively concentrates hydrophilic VOCs. PA plays the multiple roles as a water-layer inducer, a surface-complexing ligand enhancing visible light absorption, and a strong electron acceptor. Under visible light, the photogenerated electrons are rapidly scavenged by periodate to produce more •OH. PA/WO3 exhibits excellent photocatalytic activity for acetaldehyde degradation with an apparent quantum efficiency of 64.3% at 460 nm, which is the highest value ever reported. Other hydrophilic VOCs like formaldehyde that are readily dissolved into the in-situ water layer on WO3 are also rapidly degraded, whereas hydrophobic VOCs remain intact during photocatalysis due to the "water barrier effect". PA/WO3 successfully demonstrated an excellent capacity for degrading hydrophilic VOCs selectively in wide-range concentrations (0.5−700 ppmv). Photocatalytic air purification is promising but it calls for more efficient photocatalytic materials and systems. Here, the authors report a strategy to introduce an in-situ water layer on WO3 by coating hygroscopic periodic acid that effectively remove hydrophilic volatile organic compounds. [ABSTRACT FROM AUTHOR]

In this research, a novel LaCdSe-GO-TiO2 (LCS-G-T) has been synthesized by utilizing a high powersonic method under controlled condition. From the structural morphology, it is apparent that the composite is a good example of size control and low-cost synthesis with an ultrasound and scavenger effect. The synthesized LaCdSe-GO-TiO2 (LCS-G-T) composite has given a good efficiency for photocatalytic water splitting for hydrogen evolution. The implementation of high ultrasonic power has increased, the surface area decreased the particle size, due to the collapse by micro-bubbles occurred and formation of crystal enhancement. Different characterizations have been carried out for "as-prepared" composites, such as X-ray diffraction (XRD) for checking the crystallinity, scanning electron microscopy (SEM) for structural morphology, energy-dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectra (DRS), and photoluminescence (PL) spectra, and a standard three-electrode system has been used in a cyclic voltammetry test. The LaCdSe-GO-TiO2 has exposed a good photocatalytic activity in the presence and absence of several scavengers. Moreover, the applied high powersonic for hydrogen production can significantly influence the photocatalytic activity of LaCdSe-G-T. The implemented high powersonic produces electric field bridge and helps the conversion of electron from photon. [ABSTRACT FROM AUTHOR]

A novel decatungstate incorporated MOF of {[Cu(NPY)2(H2O)]2(W10O32)}·2DMF·3H2O (CuW–NPY; NPY = 3-amino-4,4′-bipyridine) has been synthesized by a diffusion method, and structurally characterized by elemental analyses, IR spectrum, UV–Vis spectrum, diffuse reflectance spectrum, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. CuW–NPY represents a novel decatungstate-based MOF with 1D quadrilateral channels (9.1 Å × 5.6 Å) constructed from Cu–NPY square grids and [W10O32]4− polyoxoanions via strong intermolecular hydrogen bonds and electrostatic interactions. Interestingly, CuW–NPY exhibits remarkable photocatalytic activities for the oxidation of cyclohexane to cyclohexanol and cyclohexanone with O2 under visible-light irradiation. The successful synthesis of CuW–NPY not only enriches decatungstate-based hybrid materials, but also represents the advantages of the decatungstate incorporated MOF for the selective oxygenation of organic compounds by O2. [ABSTRACT FROM AUTHOR]

Cyanation of aryl iodides is still challenging work for chemical researchers because of harsh reaction conditions and toxic cyanide sources. Herein, we have developed a new protocol based on the combination of the catalyst Pd@CeO2, nontoxic cyanide source K4[Fe (CN)6]·3H2O, and driving force visible light irradiation. The reaction is operated at relatively moderate temperature (55°C) and exhibits good catalytic efficiency of product aryl nitriles (yields of 89.4%). Moreover, the catalyst Pd@CeO2 possesses good reusability with a slight loss of photocatalytic activity after five consecutive runs. The reaction system based on the above combination shows a wide range of functional group tolerance under the same conditions. Reaction conditions such as temperature, time, the component of catalyst, and solutions are optimized by studying cyanation of 1‐iodo‐4‐nitrobenzene as model reaction. According to these results, the possible mechanism of Pd@CeO2‐catalyzed cyanation of aryl iodides under visible light irradiation is proposed based on the influence of visible light on the catalyst and reactant compounds. In all, we provided an environmental and economic method for preparation of aryl nitriles from cyanation of aryl iodides based on the goal of green chemistry for sustainable development. [ABSTRACT FROM AUTHOR]

Perylene diimides (PDIs) are valuable organic chromophores that stand out for their outstanding optical and redox properties. Owing to these features, PDIs have emerged as prominent dyes capable of acting as photocatalysts for numerous relevant organic transformations. This Minireview highlights the recent advances in the application of PDIs in organic photocatalysis. The various mechanistic pathways of the photo‐reduction reaction of aryl halides, recently proposed in independent studies, are discussed with an eye to unsolved challenges and forward‐looking opportunities regarding the use of PDIs within this field. [ABSTRACT FROM AUTHOR]

The development of photocascades that rapidly transform simple and readily accessible furan substrates into polycyclic alkaloid frameworks or erythrina natural products is described. Each of the sequences developed makes use of photocatalyzed energy transfer processes, which generate singlet oxygen, to set up the substrates for the second photocatalyzed reaction, wherein electron transfer generates carbon‐centered radicals for the cyclizations that give the final complex frameworks. A chemical switch has been developed that can "switch off" one photocatalyst; thus, allowing a second photocatalyst to take over control of the sequence. As a corollary, this strategy represents the first time it has been possible to use multiple photocatalysts in photocascades, and, as such, it expands significantly the reactions that can be included in such cascades and the order in which they can be initiated. [ABSTRACT FROM AUTHOR]

In this investigation, a nanocomposite made of CuO/Fe2O3 mixed oxides was fabricated as a visible-light-responsive nanocomposite via a one-pot program. The photocatalytic efficacy of the manufactured material was checked via accomplishing the photocatalytic remediation of ciprofloxacin (CIP). Incorporation of 3 wt.% CuO to Fe2O3 was sufficient to bring about an efficient photocatalyst with declined bandgap energy. 0.9 gL–1 of the fabricated heterojunction was able to completely destroy CIP when irradiated by Vis light for 40 min. The appreciative photocatalytic enhancement of the accomplished heterojunction could be connected with the enrichment of the absorbed Vis light as well as the hindrance of the recombination amid photo-engendered charge carriers. This probe is a good application to develop heterojunction of excellent capability for the photocatalytic destruction of CIP beneath Vis light irradiation. [ABSTRACT FROM AUTHOR]

Lately, heterogeneous semiconductor materials have been explored as an emerging type of efficient photocatalyst for photoredox organic synthesis. Among these semiconductors, lead halide perovskite materials demonstrate unique properties towards excellent charge separation and charge transfer, extremely long charge carrier migration, high efficiency in visible light absorption, and long excited states lifetimes, etc. as proved in ground‐breaking solar cell applications, garnering necessary merits for an efficient catalytic system for photoredox organic reactions. Here, the latest progress in heterogeneous semiconductor materials towards this endeavor is examined, with particular emphasis on lead halide perovskite nanocrystals (NCs) in photocatalytic organic synthesis. [ABSTRACT FROM AUTHOR]

The design of heterogeneous photocatalysts for organic synthesis has attracted great attention for achieving enhanced catalytic performance under light illumination. However, the effects of photocatalytic processes on organic reactions are quite complicated. In this work, we construct a series of Pd‐oxide heterostructures and then evaluate their catalytic performances on cross‐coupling reactions. The investigation results reveal that the conduction type of the oxide supports critically influences the catalytic efficiency via charge density control of metallic sites. In general, an n‐type semiconductor enhances the catalytic performance while a p‐type reduces the catalytic activity in the presence of suitable illumination conditions. Further investigation on the Pd tetrahedron‐TiO2 nanosheet hybrid structure reveals that Heck reactions take place via a radical intermediate mechanism in the presence of light, leading to a significant increase in the catalytic performance. [ABSTRACT FROM AUTHOR]

This review focuses on the discussion of the latest progress and remaining challenges in selected metal-free photocatalysts for hydrogen production. The scope of this review is limited to the metal-free elemental photocatalysts (i.e. B, C, P, S, Si, Se etc.), binary photocatalysts (i.e. BC3, B4C, CxNy, h-BN etc.) and their heterojunction, ternary photocatalysts (i.e. BCN) and their heterojunction, and different types of organic photocatalysts (i.e. linear, covalent organic frameworks, microporous polymer, covalent triazine frameworks etc.) and their heterostructures. Following a succinct depiction of the latest progress in hydrogen evolution on these photocatalysts, discussion has been extended to the potential strategies that are deemed necessary to attain high quantum efficiency and high solar-to-hydrogen (STH) conversion efficiency. Issues with reproducibility and the disputes in reporting the hydrogen evolution rate have been also discussed with recommendations to overcome them. A few key factors are highlighted that may facilitate the scalability of the photocatalyst from microscale to macroscale production in meeting the targeted 10% STH. This review is concluded with additional perspectives regarding future research in fundamental materials aspects of high efficiency photocatalysts followed by six open questions that may need to be resolved by forming a global hydrogen taskforce in order to translate bench-top research into large-scale production of hydrogen. [ABSTRACT FROM AUTHOR]

CdS/g-C3N4 (CdS/CN) type II heterojunction photocatalyst was prepared by an improved successive ionic layer adsorption and reaction process. TEM results show that the CdS nanoparticles (CdS NPs) were successfully loaded on the surface of CN. The results of PL and PEC display that the construction of CdS/CN heterojunction benefits the transmission of the photogenerated carriers and effectively inhibits the photogenerated carrier recombination in photocatalytic process. The photodegradation experiments exhibit that the 3-CdS/CN photocatalyst possesses the highest photodegradation performance over the other samples. The yields of H2 and CH4, in the presence of the best CdS/CN photocatalyst (1-CdS/CN) are 50 and 13 times stronger, respectively, than in the case of the pure CN in the photoreduction process of CO2. The CN coupling effectively improves the photocatalytic performance of CdS-based photocatalyst and inhibits the hole-induced photocorrosion of CdS NPs. A possible type II heterojunction photocatalytic mechanism has been provided. [ABSTRACT FROM AUTHOR]

A study on C9‐imide acridinium photocatalysts with enhanced photoredox catalytic activity with respect to the well‐established C9‐mesityl acridinium salt is presented. The differences observed rely on the diverse accessibility of singlet charge‐transfer excited states, which have been proven by CASPT2/CASSCF calculations, fluorescence and quenching studies. [ABSTRACT FROM AUTHOR]

In this study, via a simple one‐step method, chiral copper sulfide quantum dots (d/l‐QDs) were prepared using d‐/l‐penicillamine (d‐/l‐Pen). The anisotropy factor of d/l‐QDs was as high as 0.01. The d/l‐QDs can be used as photocatalysts to cleave proteins. Notably, the l‐QDs displayed the highest catalytic performance under left‐circularly polarized light irradiation. Mechanistic investigations indicate the generation of hydroxyl radicals as the reactive species that cause the cutting of proteins. [ABSTRACT FROM AUTHOR]

The visible-light-promoted oxidant-free decarboxylative C–H adamantylation of azoles was accomplished under ambient reaction conditions. The novel acridinium photocatalyst and cobalt synergistic catalysis enabled the C–H adamantylation under oxidant-free reaction conditions. This C–H adamantylation strategy proved viable for a wide range of substituted azoles, including benzothiazole, benzoxazole, and benzimidazoles as well as caffeine derivatives, providing an expedient access to 2-adamantyl-substituted azoles. [ABSTRACT FROM AUTHOR]

Abstract: A newly designed class of acridinium‐based organophotocatalysts bearing an imide group at the C9‐position is presented. To achieve these unprecedented structures, a synthetic strategy based on a novel straightforward oxidative Ugi‐type reaction at the benzylic position of C9‐unsubstituted acridanes was developed. The introduction of the imide‐unit affords a notable photocatalytic activity enhancement, allowing efficient transformations in different oxidative and reductive visible‐light catalytic reactions. [ABSTRACT FROM AUTHOR]

Synthesis of new mixed anion compounds under visible light has been considered as an elegant strategy of photocatalyst development for efficient solar light harvesting applications. Through combined experimental and theoretical studies, we show that a new single layer Sillen-Aurivillius perovskite Bi4Ti0.5W0.5O8Cl is a good photocatalyst under visible light. This compound prepared by a solid-state reaction method has an energy gap of 2.36 eV and the visible-light-driven photocatalytic activities for degrading Rhodamine B are much better than Bi4NbO8Cl. We conclude from density functional theory calculations that its promising water-splitting application is due to its direct band gap and more stronger hybridization between Bi-6s and O-2p orbitals than Bi4NbO8Cl.Graphical Abstract: [ABSTRACT FROM AUTHOR]

We report the efficient visible-light-responsive photocatalysis of polyoxometalates (POMs) by engineering the lowest unoccupied molecular orbitals (LUMOs). By the introduction of vanadium atoms into the γ-Keggin-type phosphotungstate, a new V3d/W5d mixed LUMO appeared to afford a visible-light-responsive catalyst (I), which showed high photocatalytic activity for aerobic oxygenation of sulfides to sulfoxides. [ABSTRACT FROM AUTHOR]

A novel heterogeneous visible light active nanophotocatalyst was produced via modification of a nanocrystalline TiO2 surface with a cobalt(ii) complex of melamine dendrimer under ultrasonic agitation, and was characterized by different techniques such as FT-IR, XPS, EDS, ICP-AES, TGA, DRS, UV-Vis, TEM and SEM. A red-shift of the band-edge and a significant reduction of the band-gap (2.7 eV) were revealed by UV-DRS. The as-prepared dendritic nanophotocatalyst significantly promoted the aerobic synthesis of benzimidazole derivatives with biological and pharmaceutical interest by a one-pot three-step process from the photooxidation of alcohols to aldehydes followed by cyclocondensation with 1,2-phenylenediamine with good to excellent yield. This process has the potential to enable a more sustainable benzimidazole synthesis. The combination of photocatalytic and catalytic reactions presented here may help to develop a new strategy towards the development of photocatalysis-based organic synthesis. [ABSTRACT FROM AUTHOR]

Abstract: A mild and selective C(sp3)−H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C−H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (−)‐ambroxide, pregnenolone acetate, (+)‐sclareolide, and artemisinin, exemplifies the utility of this new method. [ABSTRACT FROM AUTHOR]

Polyoxometalates arise as significant catalysts in the field of organic chemistry due to their diverse properties and functions. Recent progress based on experimental evidence and density functional theory (DFT) calculations provides valuable information to demystify the chemistry of decatungstate anion, W10O324−. Particularly, functionalization of aldehydes by homolytic C–H bond cleavage can be efficiently achieved when it is catalyzed by this polyoxometalate. Two reaction mechanisms have been formulated to account for the role of W10O324− in organic chemical reactions: the single electron transfer and the hydrogen atom transfer (HAT) mechanisms. In this contribution, the HAT pathway for the acylation of dimethyl maleate is experimentally and quantum-chemically explored in detail. Results based on DFT calculations under the unrestricted formalism suggest that the acylation occurs in a barrierless process upon the formation of the lowest-in-energy triplet excited state of W10O324−. These outcomes agree well with the experimental evidence since the acylated adduct was produced at a 90% yield; in this regard, side reactions like radical couplings and decarbonylation resulted in less competitiveness. The current work may therefore help in the comprehension of the mechanistic details leading to the synthesis of organic compounds photocatalyzed by polyoxometalates, even under solar radiation. [ABSTRACT FROM AUTHOR]

The photocatalyzed addition of several hydrogen donors (ethers, aldehydes, alkanes, amides) onto vinylpyridines was achieved. This approach provided access to alkylpyridines, which are important building blocks for the preparation of compounds with biological activity. The strategy was very simple and straightforward because it required only a small amount of a cheap decatungstate salt as photocatalyst. As an added advantage, the reaction could be performed under sunlight irradiation as well as under flow conditions. [ABSTRACT FROM AUTHOR]

A facile sunlight-induced derivatization of heteroaromatics via photocatalyzed C–H functionalization in amides, ethers, alkanes and aldehydes is described. Tetrabutylammonium decatungstate (TBADT) was used as the photocatalyst and allowed to carry out the process under mild conditions. [ABSTRACT FROM AUTHOR]

Various human activities like mining and extraction of mineral oils have been used for the modernization of society and well-beings. However, the by-products such as petrochemical wastes generated from such industries are carcinogenic and toxic, which had increased environmental pollution and risks to human health several folds. Various methods such as physical, chemical and biological methods have been used to degrade these pollutants from wastewater. Advance oxidation processes (AOPs) are evolving techniques for efficient sequestration of chemically stable and less biodegradable organic pollutants. In the present review, photocatalytic degradation of petrochemical wastes containing monoaromatic and poly-aromatic hydrocarbons has been studied using various heterogeneous photocatalysts (such as TiO, ZnO and CdS. The present article seeks to offer a scientific and technical overview of the current trend in the use of the photocatalyst for remediation and degradation of petrochemical waste depending upon the recent advances in photodegradation of petrochemical research using bibliometric analysis. We further outlined the effect of various heterogeneous catalysts and their ecotoxicity, various degradation pathways of petrochemical wastes, the key regulatory parameters and the reactors used. A critical analysis of the available literature revealed that TiO is widely reported in the degradation processes along with other semiconductors/nanomaterials in visible and UV light irradiation. Further, various degradation studies have been carried out at laboratory scale in the presence of UV light. However, further elaborative research is needed for successful application of the laboratory scale techniques to pilot-scale operation and to develop environmental friendly catalysts which support the sustainable treatment technology with the 'zero concept' of industrial wastewater. Nevertheless, there is a need to develop more effective methods which consume less energy and are more efficient in pilot scale for the demineralization of pollutant. [ABSTRACT FROM AUTHOR]

The efficient photosensitizing of decatungstate-based MOF with 1D channels was achieved via in situ synthesis under solvothermal conditions for light driven acceleration of β- or γ-site C–H alkylation of aliphatic nitriles. The high catalytic efficiency, excellent size selectivity, high stability and good recyclability of the photocatalyst offer an environmentally-friendly route for widening the scope of accessible nitriles in both laboratory and industry. [ABSTRACT FROM AUTHOR]

Four phosphorescent platinum(II) Schiff base complexes are screened for application in visible-light-induced cross-dehydrogenative coupling (CDC) reactions. Preliminary studies show that, among the four platinum(II) complexes, Pt3 is an efficient catalyst for CDC reactions with oxygen as an oxidant. Light irradiation ( λ>420 nm) on a mixture of the PtII complex, tertiary amine, and a variety of nucleophiles (nitroalkanes, ketones, or indoles) under aerobic conditions gives α-functionalized tertiary amines in good to excellent yields. The photoluminescence quenching experiment reveals that the CDC reaction is initiated by photoinduced electron transfer from N-phenyltetrahydroisoquinoline to the PtII complex. Further, electron spin resonance (ESR) measurements clearly indicate the formation of superoxide radical anions (O2.−) rather than singlet oxygen (1O2) during the photocatalytic reaction. [ABSTRACT FROM AUTHOR]

A versatile heterogeneous photocatalysis protocol was developed by using ruthenium bipyridyl tethered porous organosilica (Ru-POS). The versatility of the Ru-POS catalyst in organo-photocatalysis was explored by (i) oxidative aromatization of Hantzsch ester, (ii) reductive dehalogenation of alkyl halides, and (iii) functional group interconversion (FGI) of alcohols to alkyl halides. [ABSTRACT FROM AUTHOR]

A fast and efficient visible-light metal-free hydroacylation of dialkyl azodicarboxylates is described. Among a variety of activated ketones, phenyl glyoxylic acid and its ethyl ester were identified as suitable photoorganocatalysts. A range of aliphatic and aromatic aldehydes were employed, thus leading to products in high to excellent yields. [ABSTRACT FROM AUTHOR]

Photocatalytic organic syntheses are often limited by their low system efficiency and product selectivity. We demonstrate herein that intermolecular hydrogen transfer from isopropanol to acetone can be achieved efficiently on the surfaces of NaTaO3 photocatalysts, on which 2-hydroxyisopropyl radicals are produced selectively from both oxidation and reduction half-reactions and then coupled to form 2,3-dimethyl-2,3-butanediol. Such a process effectively increases the total reaction efficiency. We also found that the two half-reactions occur at different crystal facets and display a remarkably promotive interaction, which dramatically speeds up the reactions by one order of magnitude and significantly restrains side reactions. The sodium ions on the NaTaO3 surfaces play an important role in the promotive effect, likely facilitating the proton transfer between the oxidation and reduction sites. These factors make the production rate of 2,3-dimethyl-2,3-butanediol reach a very high level (10.87 mmol g−1 h−1), emphasizing the potential of photocatalytic hydrogenation and dehydrogenation in improving system efficiency of photocatalytic organic syntheses. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysis has become a comprehensively studied area of research during the past three decades due to its practical interest in applications including water-air depollution, cancer therapy, sterilization, artificial photosynthesis (CO2 photoreduction), anti-fogging surfaces, heat transfer and heat dissipation, anticorrosion, lithography, photochromism, solar chemicals production and many others. The utilization of solar irradiation to supply energy or to initiate chemical reactions is already an established idea. Excited electron-hole pairs are generated upon light irradiation of a wide-band gap semiconductor which can be applied to solar cells to generate electricity or in chemical processes to create/degrade specific compounds. While the field of heterogeneous photocatalysis for pollutant abatement and mineralisation of contaminants has been extensively investigated, a new research avenue related to the selective valorisation of residues has recently emerged as a promising alternative to utilise solar light for the production of valuable chemicals and fuels. This tutorial review will focus on the potential and applications of solid photonanocatalysts for the selective transformation of biomass-derived substrates. [ABSTRACT FROM AUTHOR]

Unaktivierte Alkyl ‐ und Arylbromide gehen eine reduktive radikalische Cyclisierung in Gegenwart eines dimeren Phosphan ‐ Gold ‐ Komplexes als Photokatalysator ein (siehe Schema; X=C(CO2Et)2, NR, O). Sonnenlicht kann als Energiequelle für diese einfache und effiziente Radikalreaktion genutzt werden, wodurch sich potenziell gefährliche und toxische chemische Reagentien wie Organostannane und chemische Initiatoren vermeiden lassen. [ABSTRACT FROM AUTHOR]

ZnO micro/nanocrystals with controlled oxygen defects are successfully prepared through annealing precursors obtained via a simple solvothermal method. The size and surface defects of the as-synthesized ZnO micro/nanocrystals increase with the solvent volume ratio of water/ethanol increasing; the BET surface areas of the corresponding samples decrease during these processes; photoluminescence reveals that the type and concentration of surface defects (oxygen vacancy and interstitial oxygen) are quite different for the samples prepared via different solvent volume ratio of water/ethanol. In addition, it is found that the photocatalytic activity of the synthesized ZnO nanocrystals is mainly dependent on the concentration of surface defects. The sample with more surface defects exhibits higher photocatalytic activity toward the degradation of methylene blue (MB). The possible photocatalytic mechanism is discussed in detail. [ABSTRACT FROM AUTHOR]

Truxene-acridine-1,8-dione derivatives ( Tr_AD) are proposed as new photoinitiators of polymerization under very soft irradiation (by a household halogen lamp), as well as laser-diode exposure at 405 nm. They exhibit a strong absorption around 380 nm. The Tr_AD/diphenyl iodonium salt/9-vinylcarbazole combination is able to promote the ring-opening polymerization of an epoxide, whereas the Tr_AD/alkyl halide/amine system is very efficient in initiating the radical photopolymerization of an acrylate. Excellent polymerization profiles are obtained. Acrylate/epoxide blends are also easily polymerized. These Tr_ADs in the three-component systems behave as photocatalysts according to oxidative cycles. The mechanisms are discussed for the different multicomponent initiating systems. [ABSTRACT FROM AUTHOR]

Photocatalytic oxidation of iron(ii) complexes by dioxygen occurred using the organic photocatalysts, 9-mesityl-10-methylacridinium ions (Acr+-Mes) and 2-phenyl-4-(1-naphthyl) quinolinium ions (QuPh+-NA), in the presence of triflic acid in acetonitrile under visible light irradiation. The electron-transfer state of Acr+-Mes produced upon photoexcitation oxidized the iron(ii) complexes, whereas it reduced dioxygen with protons to produce iron(iii) complexes and H2O2. [ABSTRACT FROM AUTHOR]