Visible Light Applications Research Articles

Visible-light-induced decarboxylative cyclization.

The application of visible light as an energy source provides a new avenue in organic transformation due to its mildness, efficiency and selectivity. In fact, recent years have witnessed remarkable advances in photoinduced decarboxylative coupling reactions involving carboxylic acids and their derivatives. Under appropriate photoredox conditions they undergo single electron transfer (SET), resulting in reactive radicals which can assemble with suitable reaction partners. Many types of carboxylic acid derivatives, such as amino acids, N-hydroxy phthalimide (NHPI) esters, α-keto acids, aliphatic/aromatic carboxylic acids, and [bis(difluoroacetoxy)iodo]benzene, can couple with a wide variety of substrates to build structurally complex molecules. The present review summarizes the last five years of progress (2020-2024) in the decarboxylative cyclization of carboxylic acids for constructing carbo-/heterocycles under visible-light irradiation. Annulation could be attained via organophotocatalysis (4CzIPN, g-C3N4, Eosin Y, methylene blue, etc.), metallaphotocatalysis or photocatalyst-free approaches. With an emphasis on the mechanistic rationales and scope of the reactions, this review focuses on recent trends in this emerging area.

Enhancing degradation of novel brominated flame retardants by sulfate modified C3N4: Synergistic effect of photocatalytic oxidation and reduction processes

Novel brominated flame retardants (NBFRs) pose serious risks to aquatic organisms and human health due to their persistence and toxicity. Herein, sulfate ions (SO42-) decorated C3N4 (SO42-@CN) photocatalyst material was synthesized for the rapid degradation of NBFRs by a synergistic effect of photocatalytic oxidation and reduction reactions. Compared with bare C3N4, the SO42-@CN exhibited efficient photocatalytic NBFRs removal performance. The degradation rates constant of hexabromobenzene and pentabromotoluene by SO42-@CN were 0.177 and 0.0906 min-1, respectively, which were 2.9 and 6.7 times higher than that by C3N4. It was confirmed that SO42-@CN could generate more active substances (such as sulfate radicals, and hydroxyl radicals) and promote the oxidation of NBFRs. Meanwhile, SO42- accelerated the separation of photogenerated electron-holes by promoting the formation of hydrogenated structures, allowing more photogenerated electrons to participate in the debromination reduction process. This work provides a new insight for the practical application of visible light driven photocatalytic technology in NBFRs residues degradation.

A review of gallium phosphide nanophotonics towards omnipotent nonlinear devices.

Gallium phosphide (GaP) has been increasingly prioritized, fueled by the enormous demands in visible light applications such as biomedical and quantum technologies. GaP has garnered tremendous attention in nanophotonics thanks to its high refractive index, indirect bandgap width of 2.26 eV, lattice perfectly matched with silicon, and omnipotent and competitive nonlinear optical properties. Herein, we review the progress and application of GaP in nanoscale devices over the past two decades. The material properties of bulk GaP are first listed, followed by a summary of the methodologies for fabricating nanoscale devices and related integration techniques. Then, we digest the operational mechanisms across different GaP-based devices on their optical linear responses. Following this, we categorize the GaP nonlinear optical effects into multiple aspects including second-harmonic generation, four-wave mixing, Kerr optical frequency combs, etc. Ultimately, we present a perspective on GaP nanophotonics in the context of coexisting and competing modes of various nonlinear effects. We believe that a comprehensive overview of unique GaP will propel these nanophotonic devices toward a mature state, underpinning foundational understanding and leveraging practical innovations.

Photo- and Electrochemical Organic Transformations Involving Radical Pathway: A Retrospection of Our Green-Chemistry-Inspired Synthetic Endeavours

AbstractThis account summarises our recent efforts (2020 to mid-2024) in designing and developing a handful of promising organic transformations for accessing several diversely functionalized biologically relevant organic scaffolds by following the green-chemistry principles with a particular focus on the application of low-energy visible light and electrochemistry. Mechanistic studies of each of these reactions established the involvement of a radical pathway.1 Introduction2 Green-Inspired Organic Transformations2.1 Visible-Light-Driven Organic Synthesis2.1.1 Synthesis of Functionalized Dihydrofuro[3,2-c]chromenones2.1.2 Synthesis of Functionalized 2-(Aryl/alkylamino)-3-(aryl/alkylselanyl)naphthalene-1,4-diones and 2-(Arylamino)-3-(arylthio)naphthalene-1,4-diones2.1.3 Synthesis of Functionalized 6-(Arylthio/arylseleno)benzo[a]phenazin-5-ols2.1.4 Synthesis of Functionalized 3-(Alkyl/benzylthio)-4-hydroxy-2H-chromen-2-ones2.1.5 Synthesis of Functionalized 2-Hydroxy-3-oxo-2,3-dihydrobenzofuran-2-carboxamides and 2-Hydroxy-3-oxo-2,3-dihydrobenzofuran-2-carboxylates2.1.6 Synthesis of Functionalized 2-Hydroxyphenylated α-Ketoamides2.2 Electrochemical Organic Synthesis2.2.1 Synthesis of 3-Selenylated/Sulfenylated Derivatives of 2-Amino-1,4-naphthoquinones2.2.2 Synthesis of Functionalized 6-(Arylthio/Arylseleno)benzo[a]phenazin-5-ols2.2.3 Synthesis of Functionalized Alkyl 2-Hydroxy-3-oxo-2,3-dihydrobenzofuran-2-carboxylates3 Conclusions

Modulate the work function of MXene in MXene/InGaN heterojunction for visible light photodetector

MXene/InGaN heterojunction photodetectors with simple structure and superior optoelectronic performance are considered a viable option for optical communication. However, the integration of MXene with InGaN faces the problem of a relatively low Schottky barrier, leading to electron backflow, which hinders the separation of carriers and limits the photoresponse of photodetectors. Herein, high-performance MXene/InGaN heterojunction photodetectors were fabricated, and the work function of Ti3C2TX was modulated to explore its effect on the performance of the photodetectors. The ascorbic acid treatment increased the work function of MXene from 4.20 to 4.34 eV, enhancing the Schottky barrier height of the heterojunction from 0.56 to 0.70 eV. The devices exhibit excellent photoresponse performances, such as a responsivity of 0.133 A W−1 and a specific detectivity of 2.81 × 1011 Jones at −1 V bias, as well as a short rise/decay time of 37.49/110 μs at 0 V bias. Additionally, the photodetectors achieve high stability that can maintain over 95% of the initial value after 3 months. This work indicates the potential for utilizing tunable MXene work function to construct high-performance optoelectronic devices for visible light applications.

Numerical analysis of on-chip acousto-optic modulators for visible wavelengths.

On-chip acousto-optic modulators that operate at an optical wavelength of 780nm and a microwave frequency of 6.835GHz are proposed. The modulators are based on a lithium-niobate-on-sapphire platform and efficiently excite surface acoustic waves and exhibit strong interactions with tightly confined optical modes in waveguides. In particular, a high-efficiency phase modulator and single-sideband mode converter are designed. We found that for both microwave and optical wavelengths below 1µm, the interactions at the cross-sections of photonic waveguides are sensitive to the waveguide width and are significantly different from those in previous studies. Our designed devices have small footprints and high efficiencies, making them suitable for controlling rubidium atoms and realizing hybrid photonic-atomic chips. Furthermore, our devices have the potential to extend the acousto-optic modulators to other visible wavelengths for other atom transitions and for visible light applications, including imaging and sensing.

Removal of organic amino derivatives from wastewater by using fluorescent nitrogen-doped GQDs under visible light and fluorescence application under ultra violet light

Photocatalysis is one of the most popular organic waste degradation treatments because it can result in the total decomposition of organic pollutants under visible light illumination. Here, we present a metal-free visible-light active catalyst for the effective decomposition of organic aromatic amino derivatives Methylene blue (MB) and Rhodamine B (RB) as model-contaminated dye molecules. Through a one-pot hydrothermal process, blue colour emissive nitrogen-doped graphene quantum dots (N-GQDs) were synthesized from urea and malic acid. The physicochemical characteristic techniques were used to analyze the surface morphology, elemental analysis, surface functional groups, absorption, emission, and band gap of prepared N-GQDs. The effective light absorption properties, transfer of electrons, separation of photoinduced charge carriers, and excellent stability with a band gap of 2.69 eV of synthesized N-GQDs have enabled the degradation of Rh B and MB up to 90 % and 86 % respectively, within 120 min of visible light irradiation. Based on extensive active species trapping experiments, a probable photocatalytic dye degradation mechanism is proposed. These N-GQDs can also be used to make fluorescent ink for imaging and security purposes.

Practice of green chemistry strategies in synthetic organic chemistry: a glimpse of our sincere efforts in green chemistry research.

This feature article summarises our recent contributions (2019-2023) in designing and developing a handful of promising organic transformations for accessing several diversely functionalised biologically relevant organic scaffolds, following the green chemistry principles, particularly focusing on the application of low-energy visible light, electrochemistry, ball-milling, ultrasound, and catalyst- and additive-free synthetic strategies.

Interfacial Charge Transfer Effects of MoS2/α-Fe2O3 Nano-Heterojunction and Efficient Photocatalytic Hydrogen Evolution under Visible-Light Irradiation.

Researchers have made efforts to develop high-productivity photocatalysts for photocatalytic hydrogen production to reduce the problem of a lack of energy. Bulk semiconductor photocatalysts mainly endure particular limitations, such as low visible light application, a quick recombination rate of electron-hole pairs, and poor photocatalytic efficiency. The major challenge is to improve solar-light-driven heterostructure photocatalysts that are highly active and stable under the photocatalytic system. In this study, the proposed nano-heterojunction exhibits a great capacity for hydrogen production (871.2 μmol g-1 h-1), which is over 8.1-fold and 12.3-fold higher than that of the bare MoS2 and bare α-Fe2O3 samples, respectively. It is demonstrated that the MoS2/α-Fe2O3 heterojunction gives rise to an enhanced visible light response and accelerated photoinduced charge carrier separation. This work provides an improved visible light absorption efficiency and a narrowed energy band gap, and presents a "highway" for electron-hole pairs to promote transfer and inhibit the combination of photoinduced charge carriers for the utilization of nano-heterojunction photocatalysts in the field of hydrogen production.

Nitrogen and carbon encapsulated heterophasic bismuth vanadate nanostructures: Synthesis and application in visible light driven textile dye degradation

Nitrogen and carbon encapsulated heterophasic bismuth vanadate nanostructures: Synthesis and application in visible light driven textile dye degradation

Diaryl-hemiindigos as visible light, pH, and heat responsive four-state switches and application in photochromic transparent polymers

Photoswitches are indispensable tools for responsive chemical nanosystems and are used today in almost all areas of the natural sciences. Hemiindigo (HI) derivatives have recently been introduced as potent photoswitches, but their full applicability has been hampered by the limited possibilities of their functionalization and structural modification. Here we report on a short and easy to diversify synthesis yielding diaryl-HIs bearing one additional aromatic residue at the central double bond. The resulting chromophores offer an advantageous property profile combining red-light responsiveness, high thermal bistability, strong isomer accumulations in both switching directions, strong photochromism, tunable acid responsiveness, and acid gating. With this progress, a broader structural realm becomes accessible for HI photoswitches, which can now be synthetically tailored for advanced future applications, e.g., in research on molecular machines and switches, in studies of photoisomerization mechanisms, or in the generation of smart and addressable materials. To showcase the potential of these distinct light-responsive molecular tools, we demonstrate four-state switching, chemical fueling, and reversible inscription into transparent polymers using green and red light as well as acid/base stimuli, in addition to a comprehensive photochemical study of all compounds.

Facile Synthesis of CdO–ZnO Nanocomposites for Photocatalytic Application in Visible Light

Facile Synthesis of CdO–ZnO Nanocomposites for Photocatalytic Application in Visible Light

Design and construction of a double Z-scheme CdS@g-C3N4/Bi2MoO6 ternary nanocomposite: Photocatalytic degradation in visible light, adsorption and electrochemical applications

Improved photocatalytic performances can be achieved by synthesizing double heterojunction nanocomposites with suitable conduction band (CB) and valence band (VB) edge potentials. In the current study, a hydrothermal approach was used to successfully synthesize a Z-scheme CdS@g-C3N4/Bi2MoO6 (CdS@GB) ternary nanocomposite with varied CdS contents. The photocatalytic efficiency of the as-synthesized materials was determined by studying the degradation of Rhodamine B (RhB) and Acetaminophen (ACM) pollutants. The experimental results revealed that 15 wt% CdS@GB (15CdS@GB) ternary composite showed the highest photocatalytic performance indicating 98.8 and 83% degradation of RhB and ACM in 35 and 140 min of irradiation, respectively. The stability of the ternary composite was also relatively high even after four consecutive cycles of photodegradation. The main reactive species involved in photodegradation processes was O2•- as revealed by the quenching experiments. The nitro blue tetrazolium (NBT) experiment further confirmed it, which showed the high production of O2•- in the reaction mixture. The synthesized ternary composites were used to study the dark adsorption of RhB, and the results confirmed the applicability of the Langmuir isotherm model. The electrochemical properties of the synthesized materials were investigated using electrochemical impedance spectroscopy (EIS) and cyclovoltammetry (CV). The results showed that 15CdS@GB has the lowest charge-transfer resistance and highest specific capacitance. Based on the findings, a double Z-scheme mechanism route was designed and presented to explain the photodegradation of the target pollutants.

Designing the heterostructured FeWO4/FeS2 nanocomposites for an enhanced photocatalytic organic dye degradation

The present study, reports a facile approach for the synthesis of FeWO4/FeS2 nanocomposites were demonstrated through hydrothermal method. The surface morphology, crystalline structure, chemical composition, optical properties of the prepared samples was analysed by different various technique. The result observed analysis indicates that, the formation of heterojunction by 2:1wt% of FeWO4/FeS2 nanohybrid has the lowest recombination rate of electron-hole pairs and the least electron transfer resistance. Due to its the broad absorption spectral range and preferable energy band gap, the (2:1) FeWO4/FeS2 nanohybrid photocatalyst exhibits an excellent ability to remove MB dye when exposed to UV–Vis. Light irradiation. Its photocatalytic activity of (2:1) FeWO4/FeS2 nanohybrid is higher than other as prepared samples due to its synergistic effects, enhanced light absorption and high charge carrier separation. Radical trapping experimental result implies that the photo-generated free electrons and hydroxyl radials are essential to degrade the MB dye. Furthermore, a possible future mechanism for FeWO4/FeS2 nanocomposites photocatalytic activity was discussed. Moreover, the recyclability analysis demonstrated that the FeWO4/FeS2 nanocomposites can be recycled multiple times. The enhanced photocatalytic activity of 2:1 FeWO4/FeS2 nanocomposites is promising for the further application of visible light driven photocatalyst in wastewater treatment.

Calculation of Irradiance from Illuminance for Artificial Light Photovoltaics Applications

Many indoor sensors are powered by artificial-light-harvesting photovoltaic (PV) cells. The performance evaluation and application of PV devices require irradiance measurement to determine input power. Standard solar irradiance meters provide measurements calibrated to sunlight spectra and do not have the low-light-level capability needed for indoor applications. Light meters, specifically designed for human visible artificial light applications, measure illuminance. This article describes a low-cost method to calculate irradiance from illuminance measurement of artificial light sources. An application example is provided.

Antimicrobial 405nm violet-blue light treatment of ex vivo human platelets leads to mitochondrial metabolic reprogramming and potential alteration of Phospho-proteome.

Continued efforts to reduce the risk of transfusion-transmitted infections (TTIs) through blood and blood components led to the development of ultraviolet (UV) light irradiation technologies known as pathogen reduction technologies (PRT) to enhance blood safety. While these PRTs demonstrate germicidal efficiency, it is generally accepted that these photoinactivation techniques have limitations as they employ treatment conditions shown to compromise the quality of the blood components. During ex vivo storage, platelets having mitochondria for energy production suffer most from the consequences of UV irradiation. Recently, application of visible violet-blue light in the 400-470nm wavelength range has been identified as a relatively more compatible alternative to UV light. Hence, in this report, we evaluated 405nm light-treated platelets to assess alterations in energy utilization by measuring different mitochondrial bioenergetic parameters, glycolytic flux, and reactive oxygen species (ROS). Furthermore, we employed untargeted data-independent acquisition mass spectrometry to characterize platelet proteomic differences in protein regulation after the light treatment. Overall, our analyses demonstrate that ex vivo treatment of human platelets with antimicrobial 405nm violet-blue light leads to mitochondrial metabolic reprogramming to survive the treatment, and alters a fraction of platelet proteome.

A Broad Spectral Photodetector Using Organic Bisindolo Quinoxaline on ZnO Nanorods

Inorganic/organic hybrids of ZnO nanorods (NRs)/bisindolo quinoxaline (BIQ) were fabricated for broadband photosensing applications. Multiple material characterizations revealed the BIQ was self-assembled in a regular form of rod-like domain and an irregular form of amorphous aggregation that were distributed on the ZnO NRs. Optical measurements showed that BIQ can absorb visible light with a wavelength up to 630 nm and effectively generate photoelectrons. Moreover, clustering of BIQ can be observed via the 3D optical microscopy. ZnO/BIQ hybrids were promising for future UV and visible light environmental monitoring applications.

Crystal strain engineering of AgBr/TiO2 for visible-light photocatalysis: Balancing light absorption and charge carrier kinetics

Addition of noble metals and/or their halides certainly improves the visible-light photocatalytic activity of TiO2, but whether this improvement is due to better photoabsorption capacity of the noble metal or enhanced photoelectrical properties of TiO2 itself, is still a subject of debate. Furthermore, the optimized load of noble metal halides at which best photocatalytic activity in TiO2 occurs hasn’t been explained in the literature consistently. Herein, we investigate the change in intrinsic lattice strain of TiO2 at different AgBr loadings which imparts selective optoelectronic properties turning AgBr/TiO2 system into a visible-light photocatalyst. XRD analysis reveals that beyond a maximum strain developed at an optimum AgBr loading level, the grain boundary interface can no longer withstand the increased strain at Ti—Ti, and Ti—O bonds and a chain of thermodynamically governed crystalline phase transformation within TiO2 begins. Faster dye degradation kinetics corroborate the hypothesis that the catalyst possessing maximum lattice strain shows superior photocatalytic properties. Photoelectrochemical studies was used to quantify the rate of charge transfer (kct) and rate of recombination (kr) of photogenerated electrons and holes. These studies revealed that although higher AgBr concentration may increase charge transfer through plasmon resonance but ultimately kr controls the total charge carrier flux that determines the photocatalytic efficicency of TiO2. Our work highlights methods in which the optimum loading of AgBr can be determined and presents fundamental insight into the role of lattice strain in balancing optical and electrical properties of TiO2 for constructing high-performance photocatalysts suitable for visible light application.

Photo-electrocatalytic based removal of acetaminophen: Application of visible light driven heterojunction based BiVO4/BiOI photoanode

The presence of organic micro-pollutants (OMPs) in wastewater treatment effluents is becoming a major threat to the water safety for aquatic and human health. Photo-electrocatalytic based advanced oxidation process (AOP) is one of the emerging and effective techniques to degrade OMPs through oxidative mechanism. This study investigated the application of heterojunction based BiVO4/BiOI photoanode for acetaminophen (40 μg L−1) removal in demineralized water. Photoanodes were fabricated by electrodeposition of BiVO4 and BiOI photocatalytic layers. Optical (UV–vis diffusive reflectance spectroscopy), structural (XRD, SEM, EDX) and opto-electronic (IPCE) characterization confirmed the successful formation of heterojunction for enhanced charge separation efficiency. The heterojunction photoanode showed incident photon to current conversion efficiency of 16% (λmax = 390 nm) at an external voltage of 1 V under AM 1.5 standard illumination. The application of the BiVO4/BiOI photoanode in the removal of acetaminophen at 1 V (external bias) vs Ag/AgCl under simulated sunlight showed 87% removal efficiency within the first 120 min compared to 66% removal efficiency of the BiVO4 photoanode. Similarly, combining BiVO4 and BiOI exhibited 57% increase in first order removal rate coefficient compared to BiVO4. The photoanodes also showed moderate stability and reusability by showing 26% decrease in overall degradation efficiency after three cycles of each 5 h experiment. The results obtained in this study can be considered as a stepping stone towards the effective removal of acetaminophen as an OMP present in wastewater.

Reactive ion beam smoothing of rapidly solidified aluminum (RSA) 501 surfaces for potential visible and ultraviolet light applications

Optical elements made of aluminum with surface roughness in the sub-nanometer range are required for applications in the visible (VIS) and ultraviolet (UV) spectral range. Rapidly solidified aluminum (RSA) 501 is an interesting candidate to produce sufficiently smooth surfaces for these applications in an ultra-precision (UP) fly-cutting process. However, the polycrystalline grain structure and precipitates contained in the material limit the achievable surface roughness. In this research, a reactive ion beam finishing process of RSA 501 is investigated employing an electron cyclotron resonance (ECR)-driven ion source using CF4 and N2 gasses. Emphasis is placed on understanding the etching mechanisms that influence the topographic evolution to provide the basis for future production processes using the material for UV optics. Material composition characterization is applied to analyze the interaction between the reactive ion species and the RSA material. Surface modification transferring the native oxide top layer to an in situ forming and developing aluminum fluoride or -nitride etch front layer is found to prevent grain orientation-dependent etching. The effect of the ion incidence angle on the etch rates of precipitates and bulk material can be used to reduce the height of precipitates protruding from the surface after the UP-machining process. A surface roughness value of Sq = 0.9 nm ± 0.1 nm (areal root mean square height) is achieved in the micro-roughness range when etching at 40° and 80° angle of incidence using collimated ion beams with CF4 process gas.