Light-sensitive Properties Research Articles

Visible light sensitive photocatalytic properties of Bi2WO6/Ag2CO3 heterojunction combined with reduced graphene oxide for the removal of organic dyes

Herein, an efficient Bi2WO6/Ag2CO3/rGO (BW/AC/rGO) heterojunction photocatalyst with different loadings of reduced graphene oxide (rGO) was synthesized by the simple hydrothermal process. The incorporated rGO serves as a redox mediator for promoting the transfer of electrons and improves the reunion time of photogenerated charge carriers. The structural analysis confirms the heterojunction formation and the optical analysis affirms the modulated bandgap and prolonged lifetime (309 ns) of charges favorable for visible light-sensitive photocatalysis. The photocatalytic studies reveal that the prepared BW/AC/rGO photocatalyst with 40 % loading of rGO exhibited a higher degradation efficiency of 97 % at 230 min in degrading rhodamine B dye. The recyclability test reveals that the photocatalyst is consistent in degrading with good photostability after four consecutive cycles. The radical trapping experiments proved that electrons and hydroxyl radicals play a crucial role in enhancing photocatalytic activity. These findings suggest that the heterojunction-designed BW/AC/rGO photocatalyst is a potential candidate for environmental remediation.

Solar light driven photochromic membranes with viologen additives in PVDF/PVP matrix

This study explores the synthesis and characterization of photochromic Polyvinylidenefluoride/Polyvinylpyrrolidone (PVDF/PVP)-based membranes, prepared through an in situ thiol-ene click reaction by incorporating viologen derivatives with different counter ions. Viologens are well-known for their light-sensitive properties and ability to change color, making them useful in various optoelectronic applications. The membranes developed in this study exhibit significant improvements in their interactions with light as a result of improved morphology and enhanced ionic conductivity (≈4 × 10−4 S cm–1) with higher porosity (Ra: 11.26–33.76 nm) compared to conventionally prepared membranes. These membranes show the ability to block almost all ultraviolet (UV) and a 90% of visible light after irradiation. Thanks to these properties, the membranes undergo visible color changes when exposed to sunlight, making them suitable for photochromic and thermochromic applications. The findings of this study could contribute to the development of innovative coating materials that enhance energy efficiency, potentially being applied to buildings, automotive windows, and other surfaces.

Electrochemical synthesis of Mn–Ni–S on titania nanotubes as new dual-function electrodes for photo-assisted asymmetric supercapacitors

Photo-assisted energy storage systems, by which solar energy can be both converted and stored, have been of interest in the past few years. Novel energy conversion and storage technology is offered by photo-supercapacitors through the combination of an energy collecting unit and a supercapacitor. This dual-application system effectively generates and stores power in a single device, which makes it appropriate for various purposes. In this work, the electrochemical anodization-electrodeposition has been employed to fabricate manganese-nickel sulfide (Mn–Ni–S) nanostructures on titania nanotubes (TNs) and used them as photoelectrodes in photo-supercapacitors. The high surface area and improved properties make TNs considerably important for energy production and storage. Photoelectrochemical analysis was carried out in a three-electrode system under a xenon (Xe) lamp irradiation using the film prepared as the photoelectrode. The highest photocurrent and photovoltage were shown by MnNiS-3/TN electrode, indicating its superior photosensitivity. Upon illumination under a 0.7 mA/cm2 current density, the area-specific capacitance of MnNiS-3/TN electrode increased from 388.3 to 723.3 mF/cm2, which is 2.0, 3.6, and 12.8 times higher than the corresponding values for NiS/TN, MnS/TN, and bare TN electrodes under similar conditions, respectively. This indicates the considerable enhancement of the capacitance of this electrode induced by light. The desirable light-sensitive properties of MnNiS/TN make it capable of simultaneous solar energy harvesting and storage. Light sensitivity makes it possible to charge MnNiS/TN optically. More importantly, upon light irradiation, the capacity can be increased from 374.7 to 630.2 mF/cm2 (current density 0.5 mA/cm2) compared to the corresponding value in the dark. Using MnNiS-3/TN as the best photoelectrode and MnS/FTO, NiS/FTO, MnNiS-1/FTO, MnNiS-2/FTO, and MnNiS-3/FTO as the counter electrodes, photo-charged through light illumination on their surfaces, five asymmetric solid-state photo-supercapacitors (ASSPS) were prepared. MnNiS-3/TN//MnNiS-3/FTO device showed the largest CV curve area, which indicated its highest areal capacitance. High capacitance gain under irradiation (155.7% at 2.0 mA/cm2) and outstanding capacitance maintenance (97.9% over 10000 cycles) were shown by this ASSPS. Furthermore, a great energy density of 4855.4 mWh/cm2 was shown by the MnNiS-3/TN//MnNiS-3/FTO device under light irradiation. This research introduces a novel approach to the development of powerful solar energy conversion/storage devices.

Conversion between digital and analog resistive switching behaviors and logic display application of photoresponsive ZnO nanorods-based memristor

Memristors have shown great application prospects in next-generation non-volatile memory (NVMs) and brain-inspired computing systems, but various application prospects have different requirements for device performance. Currently, it is difficult to precisely regulate the conversion of memristive effects between analog and digital due to the complex resistive switching mechanism. In this work, size-controlled ZnO nanorods was achieved by adjusting the concentration of the surfactant polyethyleneimine (PEI), and further research was conducted for the memristive effect of the as-prepared memristors based on ZnO nanorods with different sizes. The results showed that PEI accelerates the protonation process, leading to the increase of OH– ions, which further leads to the transition of the memristive effect of the as-prepared device from digital to analog as the PEI concentration increases. Moreover, the optical controlled logic display function was achieved in the memristor based on the light-sensitive properties of the ZnO nanorods. Therefore, this work lays the foundation that the memristor with analog and digital memristive effect can control and enrich the application prospects of memristor.

An Au25 nanocluster/MoS2 vdWaals heterojunction phototransistor for chromamorphic visual-afterimage emulation.

Color vision relies on three cone photoreceptors that are sensitive to different wavelengths of light. The interaction of three incident light wavelengths over time creates a fascinating color coupling perception, termed chromamorphic computing. However, the realization of this fascinating characteristic in semiconductor devices remains a great challenge. Herein, a mixed-dimensional optoelectronic transistor based on a novel metal nanocluster Au25(SC12H25)18 and two-dimensional MoS2 van der Waals (vdWaals) heterojunction is proposed for chromamorphic visual-afterimage emulation with red-green-blue three-color spatiotemporal coupling perception. This distinguished molecular-like electronic level of Au25 nanoclusters allows the transistor to have visible light-sensitive properties, endowing it with the ability to perceive color information. Moreover, the chromamorphic functions are realized using a color spatiotemporal coupling approach. By utilizing the photogating effect of light stimulus, the device exhibits visual experience-dependent plasticity in accordance with the Bienenstock-Cooper-Munro (BCM) learning rule. Most importantly, for the first time, intriguing visual afterimages could be implemented using a color sensitization approach based on a close relationship between visual persistence and negative afterimages. These results represent an important step towards a new generation of intelligent visual color perception systems for human-computer interaction, bionic robots, etc.

Stress and light sensitive dual-mechanical property of acylhydrazone crystal

Long acicular crystals derived from 4-bromobenzhydrazide and 9-anthraldehyde exhibit both stress-induced mechanical bending and blue-light-induced photomechanical bending.

A Perspective on the Potential of Opsins as an Integral Mechanism of Photobiomodulation: It's Not Just the Eyes.

Objective: To investigate the potential relationship between opsins and photobiomodulation. Background: Opsins and other photoreceptors occur in all phyla and are important in light-activated signaling and organism homeostasis. In addition to the visual opsin systems of the retina (OPN1 and OPN2), there are several non-visual opsins found throughout the body tissues, including encephalopsin/panopsin (OPN3), melanopsin (OPN4), and neuropsin (OPN5), as well as other structures that have light-sensitive properties, such as enzymes, ion channels, particularly those located in cell membranes, lysosomes, and neuronal structures such as the nodes of Ranvier. The influence of these structures on exposure to light, including self-generated light within the body (autofluorescence), on circadian oscillators, and circadian and ultradian rhythms have become increasingly reported. The visual and non-visual phototransduction cascade originating from opsins and other structures has potential significant mechanistic effects on tissues and health. Methods: A PubMed and Google Scholar search was made using the search terms "photobiomodulation", "light", "neuron", "opsins", "neuropsin", "melanopsin", "encephalopsin", "rhodopsin", and "chromophore". Results: This review was examined the influence of neuropsin (also known as kallikrein 8), encephalopsin, and melanopsin specifically on ion channel function, and more broadly on the central and peripheral nervous systems. The relationship between opsins 3, 4, and 5 and photobiomodulation mechanisms was evaluated, along with a proposed role of photobiomodulation through opsins and light-sensitive organelles as potential alleviators of symptoms and accelerators of beneficial regenerative processes. The potential clinical implications of this in musculoskeletal conditions, wounds, and in the symptomatic management of neurodegenerative disease was also examined. Conclusions: Systematic research into the pleotropic therapeutic role of photobiomodulation, mediated through its action on opsins and other light-sensitive organelles may assist in the future execution of safe, low-risk precision medicine for a variety of chronic and complex disease conditions, and for health maintenance in aging.

Epitaxial Growth of 2D Ultrathin Metastable γ-Bi2 O3 Flakes for High Performance Ultraviolet Photodetection.

Ultraviolet detection is of great significance due to its wide applications in the missile tracking, flame detecting, pollution monitoring, and so on. The nonlayered semiconductor γ-Bi2 O3 is a promising candidate toward high-performance UV detection due to the wide bandgap, excellent light sensitivity, environmental stability, nontoxic and elemental abundance properties. However, controllable preparation of ultrathin 2D γ-Bi2 O3 flakes remains a challenge, owing to its nonlayered structure, metastable nature, and other competing phases. Moreover, the UV photodetectors based on 2D γ-Bi2 O3 flake have not been implemented yet. Here, ultrathin (down to 4.8nm) 2D γ-Bi2 O3 flakes with high crystal quality are obtained via a van der Waals epitaxy method. The as-synthesized single-crystalline γ-Bi2 O3 flakes show a body-centered cubic structure and grown along (111) lattice plane as revealed by experimental observations. More importantly, photodetectors based on the as-synthesized 2D γ-Bi2 O3 flakes exhibit promising UV detection ability, including a responsivity of 64.5 A W-1 , a detectivity of 1.3 × 1013 Jones, and an ultrafast response speed (τrise ≈ 290 µs and τdecay ≈ 870 µs) at 365nm, suggesting its great potential for various optoelectronic applications.

Adsorption and photocatalytic removal of Rhodamine B from wastewater using carbon-based materials

The removal of Rhodamine B dyes (RhB) from wastewater, using the conventional water treatment techniques, usually involves some challenging processes. This is challenging because RhB is a highly soluble and persistent dye found in wastewater. Although some efficient physiochemical techniques have been reported, the limitations associated with these technologies, such as the production of secondary wastes in the chemical precipitation process, cannot be overlooked. Photocatalysis, on the other hand, could transform the dye molecules to less toxic or non-toxic final products without the generation of secondary wastes. Therefore, the combined use of photocatalysis and adsorption processes for the removal of RhB from water has been found to be highly efficient. However, the development of materials that possess efficient adsorption and photocatalytic properties remains a major challenge since most of the known materials have a low adsorption capacity and may not be photostable. Carbon-based materials have been used as an efficient material for the removal of RhB from wastewater due to their high adsorption capacity and light-sensitive properties. In this report, the properties, synthesis and use of the carbon-based materials for the removal of RhB from wastewater are discussed in detail. Different factors that affect the removal of RhB dyes from wastewater and the mechanism of photocatalysis and adsorption isotherms are critically reviewed. Furthermore, limitations of carbon-based materials as both adsorbents and photocatalysts are presented, and the possible methods for overcoming these limitations are also investigated.

Stimuli-responsive Ca-alginate-based photothermal system with enhanced foliar adhesion for controlled pesticide release

For minimizing volatilization and leaching of pesticides, and enhancing their residence time on crop surfaces, we synthesized and characterized a novel intelligent pesticide delivery system. Therein, imidacloprid (IMI) was adsorbed by polydopamine modified kaolin (PK) with high adsorption property through hydrogen bonds. Ca-alginate was used as a structural matrix of the system and a protective shell to hinder the pesticide burst release from PK, and endowed the system with unique pH-sensitive property for IMI release. The amino silicone oil (ASO) coating could bind with the waxy layer of crop leaves by the theory of “similarity-intermiscibility”, which increased the adhesion of composite on crop leaves. Moreover, by the excellent light-sensitive property of detonation nanodiamond (DND) and temperature-responsive performance of poly(N-isopropylacrylamide) (PNIPAm), the release of IMI from the functional system could be adjusted by sunlight. Besides, the composite displayed high control efficacy. This novel composite can promote the targeting ability and utilization efficiency of pesticides, thus having a huge potential application prospect in agriculture.

Improvement of light stability of DHR123 radio fluorogenic nano clay gel dosimeter by incorporating a new dispersant

A tissue-equivalent three-dimensional dosimeter is being developed to verify dose distributions for radiotherapy. Recently, we have reported a nanocomposite fluorescent gel (NC-RFG) dosimeter that enables readout by the fluorometry, which is more sensitive than absorption method in principle. However, irradiating by an excitation light for a dose information readout also produces fluorescent dyes and is not negligible in the low-dose irradiation range under 1 Gy. In this study, we investigate new additives to improve the NC-RFG’s light stability. We successfully suppressed the light-sensitive property of the NC-RFG to at least 10% of normal conditions by adding either N-vinylpyrrolidone or pyridine as a new dispersant that is presumed to break up aggregation of rhodamine 123 (RD123) and dihydrorhodamine 123 (DHR123) to stop photoexcited RD123 from oxidizing the adjacent DHR123. We also provide a detailed study of sensitivity characteristics such as dose rate dependence for fluorescent gel dosimeters.

Design of DOX-GNRs-PNIPAM@PEG-PLA Micelle With Temperature and Light Dual-Function for Potent Melanoma Therapy.

Objective: The aim of this study was to construct light and temperature dual-sensitive micellar carriers loaded with doxorubicin (DOX) and gold nanorods (DOX-GNRs-PNIPAM@PEG-PLA, DAPP) for melanoma therapy.Methods: The DAPP self-assembled using fine-tuned physicochemical properties in water. The DAPP structure, temperature- and photo-sensitivity, drug-release, in-vitro serum stability, and cytotoxicity against melanoma B16F10 cells were evaluated in detail. The corresponding in-vitro and in-vivo therapeutic mechanisms were then evaluated using a B16F10-melanoma bearing BALB/c nude mouse model (B16F10).Results: The light and temperature sensitive micellar drug-delivery system assembled from block copolymer and gold nanorods exhibited a narrow particle size and size distribution, good biocompatibility, well-designed photo-temperature conversion, controlled drug release, and high serum stability. Compared with the free DOX- and PBS-treated groups, the cell endocytosis-mediated cytotoxicity and intra-tumor accumulation of DAPP was markedly enhanced by the NIR-light exposure and induced potent in-vivo tumor inhibitory activity.Conclusion: The design of DAPP, a dual-functional micellar drug-delivery system with temperature- and light-sensitive properties, offers a new strategy for skin-cancer therapy with a potent therapeutic index.

The application of Zeolitic imidazolate frameworks (ZIFs) and their derivatives based materials for photocatalytic hydrogen evolution and pollutants treatment

• The application of ZIF/ZIF derivative based composite photocatalysts was reviewed. • Special attention has been paid to the catalytic mechanism. • The synergistic effects between the components are discussed. • The challenges and opportunities in this interesting field are presented. To solve the problem of the global energy shortage and the widespread pollution of the environment, semiconductor photocatalytic technology has been widely studied. Zeolitic imidazolate frameworks, a sub-family of metal-organic frameworks, have emerged as potential candidates for photocatalysis due to their intrinsic porous characteristics, abundant functionalities, rapid electron transfer ability, and exceptional thermal and chemical stabilities. Besides, a thermal treatment of zeolitic imidazolate frameworks can result to functional materials that have the similar structure characteristic, but superior light sensitivity and charge transfer properties. Moreover, the photocatalytic activity of zaeolitic imidazolate frameworks and their derivatives can be largely improved by combining photoactive semiconductors/ molecules which serve as light harvesting centers/electronic mediators. This paper presents a first review of the application of zaeolitic imidazolate frameworks and their derivatives -based materials for visible-light-induced photocatalytic hydrogen evolution and pollutants treatment. The representative studies are carefully summarized and discussed. Special emphasis is given to the synergistic effects between the components in the composite catalyst for enhanced photocatalysis. At the end of this review, the current achievements together with major challenges in the field are discussed and the next possible development directions are proposed.

Light sensitivity and electrical properties of two-dimensional nanoleaf CuO/ITO thin films

Leaf-like copper oxide (CuO)/ITO thin film was prepared by chemical bath deposition technique. Two-dimensional nature of the heterojunction thin film is due to the result of interface between ITO and CuO thin film. The structure, surface morphology, chemical composition, and optical properties of the thin film have been studied using XRD, FESEM, EDX, UV–Vis spectrophotometry. The vibration spectrum of the thin film was studied using FTIR spectrometer and the thin film was subjected to the Hall effect measurement. I–V measurements were performed under the illumination of a tungsten halogen lamp and measured parameters such as open circuit voltage, short circuit current density and fill factor. The electrical conductivity, current density-voltage characteristic, and conversion efficiency (3.097%) of CuO/ITO nanoleaves are high compared to the CuO film and may apply numerous applications in solar cell devices.

Depth-dependent soil mixing persists across climate zones

Soil mixing over long (>102 y) timescales enhances nutrient fluxes that support soil ecology, contributes to dispersion of sediment and contaminated material, and modulates fluxes of carbon through Earth's largest terrestrial carbon reservoir. Despite its foundational importance, we lack robust understanding of the rates and patterns of soil mixing, largely due to a lack of long-timescale data. Here we demonstrate that luminescence, a light-sensitive property of minerals used for geologic dating, can be used as a long-timescale sediment tracer in soils to reveal the structure of soil mixing. We develop a probabilistic model of transport and mixing of tracer particles and associated luminescence in soils and compare with a global compilation of luminescence versus depth in various locations. The model-data comparison reveals that soil mixing rate varies over the soil depth, with this depth dependency persisting across climate and ecological zones. The depth dependency is consistent with a model in which mixing intensity decreases linearly or exponentially with depth, although our data do not resolve between these cases. Our findings support the long-suspected idea that depth-dependent mixing is a spatially and temporally persistent feature of soils. Evidence for a climate control on the patterns and intensities of soil mixing with depth remains elusive and requires the further study of soil mixing processes.

Noninvasive optical activation of Flp recombinase for genetic manipulation in deep mouse brain regions

Spatiotemporal control of gene expression or labeling is a valuable strategy for identifying functions of genes within complex neural circuits. Here, we develop a highly light-sensitive and efficient photoactivatable Flp recombinase (PA-Flp) that is suitable for genetic manipulation in vivo. The highly light-sensitive property of PA-Flp is ideal for activation in deep mouse brain regions by illumination with a noninvasive light-emitting diode. In addition, PA-Flp can be extended to the Cre-lox system through a viral vector as Flp-dependent Cre expression platform, thereby activating both Flp and Cre. Finally, we demonstrate that PA-Flp–dependent, Cre-mediated Cav3.1 silencing in the medial septum increases object-exploration behavior in mice. Thus, PA-Flp is a noninvasive, highly efficient, and easy-to-use optogenetic module that offers a side-effect-free and expandable genetic manipulation tool for neuroscience research.

Development of an image biosensor based on an optogenetically engineered cell for visual prostheses.

Visual prostheses provide blind patients with artificial vision via electrical stimulation of surviving visual cells resulting in partial restoration of vision in many patients. However, high-resolution visual perception, long-term biocompatibility and safety remain the significant challenges of existing visual prostheses. Here, we present a novel method to develop a new visual prosthesis using living cells as integrated electronics and implantable microelectrodes. The living cells modified with channelrhodopsin-2 showed excellent light-sensitive properties and encoded image information with cellular deformations triggered by light stimulation. The photoresponsive properties of the cells were determined using a single pixel imaging system, which indicated that the cells can act as a good light-sensitive biosensor. Additionally, the imaging feasibility of the cells was further validated through successful and clear imaging of several object scenes using the same system. This work represents a step toward the design and use of living cells as an image biosensor for the development of a new generation of high-resolution visual prostheses.

Enhanced visible light photocatalytic activity of BiFeO3-ZnO p-n heterojunction for CO2 reduction

The visible light photocatalytic ability of bismuth ferrite-zinc oxide composites with different molar ratios was investigated for conversion of CO2 in the gas phase. The catalysts were successfully synthesized by hydrothermal method, and characterized by XRD, EDS, FESEM, UV–vis, and PL analyses. Also, the gaseous products were identified by FTIR technique. The FESEM illustrated the well crystalline particles of ZnO and BiFeO3. The UV–vis and PL analyses revealed that by increasing BiFeO3 content, the composites showed higher optical response in visible region and higher efficiency of charge separation, respectively. Compared with the pure ZnO and BiFeO3, which had poor performances under visible light irradiation, the as-synthesized photocatalysts showed the enhanced visible light photocatalytic activity for CO2 reduction. The highest photocatalytic conversion of CO2, 21%, was achieved by the as-synthesized photocatalyst with molar ratio of 1:1 under visible light. The enhanced visible light photocatalytic activity of BiFeO3-ZnO was assigned to the synergistic effect of p-n heterojunction and visible light sensitive property of perovskite structure of BiFeO3.

Triple-Responsive Block Copolymer Micelles with Synergistic pH and Temperature Response

Multifunctional, stimuli-responsive block copolymers have been prepared via the sequential atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and the in-house synthesized 1′-(2-methacryloxyethyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline) (SPMA) monomer. Two PDMAEMA-b-PSPMA diblock copolymers, containing 3 and 14 mol % SPMA, were synthesized. The amphiphilic nature of the PDMAEMA-b-PSPMA diblock copolymers led to the formation of well-defined spherical micelles, comprising a hydrophobic PSPMA core and a hydrophilic PDMAEMA shell, in water. The combination of the pH- and temperature-responsive character of PDMAEMA with the pH-, temperature-, and light-sensitive properties of the PSPMA block has resulted in a complex responsive behavior of the copolymer micelles in aqueous solution, when applying three different external stimuli (i.e., light irradiation, pH, and temperature). More importantly, the synergistic response of the block copolymer micelles ...

Fabrication ofsolar cell usingextracted biomolecules from tea leaves and hybrid perovskites

In today’s world where energy plays an important role in everyone’s life, major stress is given to cultivate alternative source of energy rather than the conventional one. One of the most promising out comings of un-conventional source of energy is the dye sensitized solar cell (DSSC). The low cost fabrication of DSSC indicating the economic viability. In this present research work we have extracted tea catechins from green tea through several steps which fall into several categories: material treatments, extraction of tea constituents from tea leaves, concentration of the extracted constituents, separation and isolation of tea catechins from other impurities, and finally drying of catechins. Characterization of the material was carried out using XRD, SEM, UV, FTIR tools. The uniform distributed single phase nanoparticles were found using structural characterization tools with no impurities. Optical property shows good light sensitive behavior. Apart from the medicinal and other applications of tea catechins we were aimed to use catechins as energy harvesting material with the combination of Hybrid Perovskites. For this purpose this biomolecules has been deposited over the (TiO2-CH3NH3PbI3) thin film for fabrication of solar cell. A good light sensitive electrical property showed that this biomolecules has good application in solar cell for their free radical scavenging ability.