Visible Light Energy Research Articles

Light-Assisted Catalysis and the Dynamic Nature of Surface Species in the Reverse Water Gas Shift Reaction over Cu/γ-Al2O3.

The reverse water gas shift (RWGS) reaction converts CO2 and H2 into CO and water. We investigated Cu/γ-Al2O3 catalysts in both thermally driven and light-assisted RWGS reactions using visible light. When driven by combined visible light and thermal energy, the CO2 conversion rates were lower than in the dark. Light-assisted reactions showed an increase in the apparent activation energy from 68 to 87 kJ/mol, indicating that light disrupts the energetically favorable pathway active in the dark. A linear correlation between irradiance and decreasing reaction rate suggests a photon-driven phenomenon. In situ diffuse reflectance infrared Fourier transform spectroscopy and TD-DFT analyses revealed that catalyst illumination causes significant, partly irreversible surface dehydroxylation, highlighting the importance of OH groups in the most favorable RWGS pathway. This study offers a novel approach to manipulate surface species and control activity in the RWGS reaction.

Simultaneous enhancement of visible light absorption and energy storage performances of W5+ implanted WO3-x thin film electrodes

Herein, we report the implantation of oxygen vacancy dopants in electro-coated WO3 thin film electrodes for enhanced energy and environmental applications. The implantation method involved partial de-oxidation in sodium borohydride to introduce oxygen vacancies into the WO3 electrodes. The doped WO3-x demonstrated a significantly lowered average band energy of 2.11 eV, indicating its ability to absorb over 75 % of the visible light spectrum. Moreover, a thin film asymmetric supercapacitor assembled with WO3-x negatrode demonstrated an improved areal capacitance of 1.15 mFcm−2 and energy density of 0.33 μWhcm−2 while consuming power at 17.50 μWcm−2 when cycled at 25 μAcm−2. Our solution-processed technique allows for controllable vacancy implantation and binder-free coating of WO3-x on various substrates. It significantly reduces the processing time and requires low energy consumption, making it a practical and efficient method for enhancing the overall photo-conversion and energy storage performances of WO3-based electrodes.

Low thickness effect on the properties of Mn-doped ZnO thin films synthesized by sol-gel spin coating technique

In this study, 7% manganese-doped zinc oxide (MZO) thin films with varying low thicknesses were synthesized using the spin coating method. The structural, optical, and morphological properties of MZO films with different film thickness, were systematically investigated. The crystallite structure, superficial morphology, and optical characteristics were analyzed using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and ultraviolet–visible spectroscopy (UV-Vis). Structural analysis confirmed that all films exhibit a hexagonal wurtzite phase with a pronounced peak along the c-axis, and slight variation in low thickness significantly affected the structural parameters. The surface morphology demonstrated good uniformity, characterized by rounded grain shapes in the plane, while surface roughness was found to be increased with increasing film thickness. Optical analysis revealed that as the number of coatings increased, both transmittance and band gap energy decreased, accompanied by a redshift in the absorption edge across all samples. This behavior is attributed to light scattering, as well as an increase in the refractive index and dielectric function with visible light energy, influenced by the number of layers and corresponding crystallite size.

Evaluating Electronic Properties of Self‐Assembled Indium Phosphide Nanomaterials as High‐Efficient Solar Cell

ABSTRACTGeometries and electronic properties associated with relative stabilities and energy gaps of porous (InP)12n (n = 1–12) nanoclusters (NCs) (nanowires and nanosheets) are systemically studied by density functional method. The relative stabilities of (InP)12n NCs through the calculated fragmentation energies and cluster‐binding energies are determined and discussed. Interestingly, the calculated energy gaps of (InP)12n nanowires and nanosheets are localized at regions of visible light energy ranges. (InP)12n are relatively wide‐band semiconductor solar energy nanomaterial. The calculated density of states reveals large‐sized porous (InP)12n nanosheets and nanowires with narrow pore size distribution and slight thickness and a large surface area manifest ultrahigh specific capacitance of trapping solar light energies and high light‐to‐electricity conversion efficiencies in solar energy absorption or conversion or photovoltaicsm. Particularly, (InP)12n NCs maintain their elemental properties of individual (InP)12 clusters in the energy gaps of (InP)12n (n > 4). NCs are almost independent of variable sizes. Specifically, the size‐dependent charge transfers of In atoms in (InP)12n NCs exhibit that ionic and covalent bonding exist in (InP)12n NCs and can stabilize (InP)12n NCs. Comparison with experiment results available is made.

Development of flexible and mesoporous CdS/ZnS/PVDF nanocomposites with remarkable organic dye degradation performance under natural sunlight

The engineering of polymer-based nanocomposites is a highly promising strategy for improving both the efficiency and stability of catalysts used in wastewater treatment. In this work, we explore the efficacy of flexible CdS/ZnS/PVDF nanocomposite films towards degradation of Malachite Green dye under low energy visible light and ambient sunlight. Films with varying weight percentage of CdS/ZnS nanofillers (0 %, 5 %, 10 %, 15 %, 20 %) were successfully prepared by solution casting method and the physiochemical properties were characterized using various techniques such as XRD, SEM, AFM, EDX, BET, UV–Vis DRS and FTIR. Pore diameter of 5.5 nm was observed, indicating that CdS/ZnS is mesoporous in nature. Under the optimum photocatalytic condition of 15 ppm dye concentration and pH 9, 15 wt% CdS/ZnS/PVDF showed the maximum photodegradation efficiency of 93.5 % in 30 min. The sample exhibited excellent reusability for five consecutive runs of the experiments which show a degradation percentage of 92.1 % in the fifth run and the scavenging study established that superoxide radicals play the major role in the photodegradation process. The experiments under natural sunlight on three separate days showed a remarkable photodegradation performance of 89 %, 93.4 % and 93.6 % highlighting the potential of CdS/ZnS/PVDF nanocomposites for sustainable wastewater treatment under natural sunlight.

Visible light-activated dye-sensitized TiO2 antibacterial film: A novel strategy for enhancing food safety and quality

Antibacterial packaging holds promise in addressing food spoilage by inactivating bacteria, but current antimicrobial packaging solutions face challenges like depletion of antibacterials and concerns of antibiotic abuse. In response to these limitations of existing packaging materials, we developed a novel antibacterial packaging film by incorporating titanium dioxide (TiO2)- tetra(4-carboxyphenyl) porphyrin (TcPP) conjugates into cellulose nanofibrils (CNF) films. Unlike conventional antimicrobial packaging, this film harnesses visible light energy to excite electrons from TcPP to TiO2, generating reactive oxygen species (ROS) that inactivate bacteria without relying on antibiotics. Results demonstrated that the film reduced 4.5, 4.6, 4.1, and 4.7-log Escherichia coli, Pseudomonas fluorescens, Leuconostoc lactis, and Listeria innocua, respectively, in phosphate-buffered saline within 72h under 6000 lux light (3.13mW/cm2). The antimicrobial efficacy decreased as the light intensity decreased. Notably, it retains significant antimicrobial properties even under an extremely low light intensity of 600 lux (0.60mW/cm2). The analysis also revealed that singlet oxygen and hydrogen peroxide are the major generated ROS from the film under light exposure. When applied to cucumbers, the film reduced E. coli by 3.5 logs after 48-hour light exposure. The designed photocatalytic antibacterial film represents a major advancement in sustainable food preservation, reducing food waste by extending the shelf life of fresh produce.

Broad spectrum catalysis using Ca3Sn2S7 Ruddlesden-Popper perovskite under multi-stimulus

Advanced oxidation processes emerged as effective alternatives to traditional approaches. The efficacy of these methods significantly depends on the intrinsic properties of a catalyst material. Semiconductor materials with robust photo absorption alongside inherent polarization emerged as subjects of great interest. In this study, we synthesized two-dimensional Ca3Sn2S7 nanosheets oriented as Ruddlesden-Popper type perovskite structure. The optimal compositions of these nanosheets exhibit excellent physical and optical characteristics while varying Sn ratios significantly impact the properties. Impressively, these compositions boast a wide optical window that spans from the visible to the far infrared region, featuring a narrow bandgap of approximately 0.6 eV. Band potentials in a positive regime make it highly favorable for the oxidation process. The electrochemical analysis further validates high mobility with low resistance in both compositions. The catalytic efficiency of the synthesized nanosheets is evaluated using rhodamine-B. Three energy sources, i.e., visible light, laser, and ultrasound vibrations, decomposed 96 %, 90 %, and 78 %, respectively, in 30 min. Remarkably accelerated degradation rates are achieved under each stimulus, owing to the presence of oxidative optical bands, large surface area, and potential internal polarization within the nanosheets. Preliminary findings strongly indicate the immense potential of this compound in catalytic and photovoltaic applications.

Synthesis, characterization and correlation studies on the Ni–Zn–Mn ferrite as a photocatalyst

Samples of Ni0.3Zn0.7−xMnxFe2O4 (x = 0, 0.15, 0.25, 0.35, 0.45, 0.55) nanoparticles (NPs) were synthesized by auto-combustion flash method. These ferrites were used as catalysts for photodegradation of methylene blue (MB) dye utilizing visible light energy. Structural analysis was carried out using the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, while nanoparticle dimensions were elucidated through transmission electron microscopy (TEM). The magnetic and optical behaviours were unveiled via vibrating sample magnetometer and UV–VIS spectroscopy, respectively. The XRD outcomes established the presence of a cubic spinel-type structure for the studied ferrite samples. The FTIR spectra unveiled two absorption characteristic bands of the spinel ferrite. TEM images revealed nanoscale dimensions of ferrite NPs with the range from 21.1 to 51.8 nm. The optical features exhibited an indirect band gap energy spanning from 4.25 to 4.36 eV. Magnetization behaviour displayed a sinusoidal trend corresponding to varying Mn concentrations. The ferrite NPs catalyst (10 mg) yield photodegradation efficiency ranged from 22.8 to 33.9% for 100 ml MB dye solution after 120 min of light irradiation. The effects of dye concentration and catalyst dose on the degradation efficiency were examined using the Ni0.3Zn0.35Mn0.35Fe2O4 catalyst with highest degradation (= 33.9%). On the other hand, the dependence of the degradation efficiency on the structure, morphological, magnetic and optical properties of the photocatalyst was investigated. The findings of this study underscore the potential of the prepared ferrite nanoparticles for advanced applications in environmental restoration.Graphical abstract

(Invited) Changes in Electric Double-Layer Structures Under Localized Surface Plasmon Excitation

For the visible light energy conversion, the localized surface plasmon resonance (LSPR), which is the collective oscillations of free electrons, should be promising. With the excitation of LSPR, the highly localized electric field generates in the vicinity of metal nanostructures. It is interesting that various unique photo-response properties, such as chemical reactions or molecular excitations, can be observed due to the enhancement of light-matter interaction.[1] To understand and control such mediated chemical reactions or electrochemical reactions, the precise understanding about the electrified interfaces of plasmonic nanostructures should be required.Especially in the electrochemical system, the electric double layer is formed due to the difference in electrochemical potential between the metal interface and solution. The study of the surface potential is important for the design of chemical reactions because the surface potential at the liquid-solid interface is dependent on the physical properties of the systems. The zeta potential which is the potential of the slipping surface near the Stern layer of the diffusion layer could provide such information. From this point of view, in this study, we investigated the electric double-layer structures through the examination of the zeta potential under LSPR excitation condition. To obtain the zeta potential, we have performed the streaming potential method using Au nanoisland structures under visible light illuminations to excite the LSPR. It was interesting that the zeta potential was drastically changes under the visible light illumination conditions. This zeta potential change indicates the changes in the electric double layer structures through the excitation of LSPR. Through the investigations of incident wavelength dependence or the substrate dependences, the effects for the LSPR excitations on the electric double layer structure have been revealed. The present work would provide the fundamental knowledge about the effect on the LSPR excitation at solid-liquid interfaces.[1] H. Minamimoto et al., Acc. Chem. Res., 2022, 55(6), 809.

Correlations between X-rays, visible light and drive-beam energy loss observed in plasma wakefield acceleration experiments at FACET-II

This study documents several correlations observed during the first run of the plasma wakefield acceleration experiment E300 conducted at FACET-II, using a single drive electron bunch. The established correlations include those between the measured maximum energy loss of the drive electron beam and the integrated betatron X-ray signal, the calculated total beam energy deposited in the plasma and the integrated X-ray signal, among three visible light emission measuring cameras and between the visible plasma light and X-ray signal. The integrated X-ray signal correlates almost linearly with both the maximum energy loss of the drive beam and the energy deposited into the plasma, demonstrating its usability as a measure of energy transfer from the drive beam to the plasma. Visible plasma light is found to be a useful indicator of the presence of a wake at three locations that overall are two metres apart. Despite the complex dynamics and vastly different time scales, the X-ray radiation from the drive bunch and visible light emission from the plasma may prove to be effective non-invasive diagnostics for monitoring the energy transfer from the beam to the plasma in future high-repetition-rate experiments.

Rose bengal photocatalyzed expeditious multicomponent synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones/thiones under visible light irradiation

AbstractThe combination of visible light, a renewable and green energy source, and rose bengal, a non‐toxic organic dye as a photoredox catalyst, is an easy and efficient method for synthesizing 3,4‐dihydropyrimidin‐2(1H)‐ones/thiones in EtOH at ambient temperature in very short reaction time. The present work offers simple operation, easy workup, rapid conversion, and excellent product yields, while accommodating a wide range of substrates. Rose bengal‐based photocatalytic approach permits foremost sustainability, which delivers economic and environmental rewards.

Hydrostatic pressure effects on Francium-based halide perovskites FrMI3 (M = Ca, Sr): A pathway to enhanced optoelectronic performance

This study delves into the realm of ab-initio modeling to investigate the potential of Francium (Fr)-based halide perovskite materials as a Lead (Pb)-free alternative. The structural, electronic, bonding, optical, elastic, and mechanical properties of FrMI3 (M = Ca, Sr) are investigated under various hydrostatic stresses, ranging from 0 to 30 GPa, to enhance our understanding of their potential applications in optoelectronic fields. The assessment of structural and thermodynamic stability involved the examination of various factors including Goldschmidt’s tolerance factor, formation energies, and lattice dynamical properties. When subjected to hydrostatic pressure, the lattice parameter undergoes a reduction for FrCaI3 from 6.233 (5.862) to 5.118 (5.105) Å, and for FrSrI3 from 6.480 (6.027) to 5.327 (5.217) Å, utilizing GGA-PBE (hybrid HSE06) potential. Employing the hybrid HSE06 functional refines the accuracy of the band gap, and the values decrease from 3.853 to 2.787 eV for FrCaI3 and from 3.839 to 2.343 eV for FrSrI3 when pressure is applied. The wider band gaps of these materials allow for a broader range of optoelectronic implementations. As the pressure increases, the band gap narrows due to its transition from the ultraviolet to the visible light energy area. This narrowing enhances conductivity, making it a strong contender for tandem photovoltaics and microelectronics. Furthermore, the existence of ionic and covalent bonds between Fr-I and Ca/Sr-I, respectively, is validated through the calculation of bond lengths. Applying pressure improves the optical responses, showcasing its utility in various semiconductor technologies within the visual range and extending its application beyond the restricted use in the UV domain. Similarly, hydrostatic pressure has a significant impact on mechanical characteristics without compromising stability.

QM, molecular docking and molecular dynamics investigation on acidic phospholipase A2 2 protein and acidic phospholipase A2 3 protein with silane dimethyl

Phytochemicals and non-nutritive plant substances can protect humans from various diseases by possessing anti-inflammatory or anti-disease properties. The Andrographis Paniculata species has been the primary focus of extensive pharmacological and phytochemical research. QM concepts are being applied scientifically in chemical and biological problems, with molecular docking and molecular dynamics techniques being crucial in-silico drug development. Absorptions in Andrographis Paniculata come from charge transfer due to visible light's energy emissions, with GCMS– results indicating its chemical components possess antibacterial properties. The PES concept aids in the intuitive understanding of mathematical concepts, while RDG recreates the complete distribution of electronic pairings, including interatomic bonding regions, lone pairs, and cores. Molecular dynamics is crucial for protein-ligand docking due to its accurate binding free energy calculations and profound understanding of the dynamic nature of protein-ligand interactions.

Biocompatible PANI-Encapsulated Chemically Modified Nano-TiO2 Particles for Visible-Light Photocatalytic Applications.

Polyaniline (PANI) constitutes a very propitious conductive polymer utilized in several biomedical, as well as environmental applications, including tissue engineering, catalysis, and photocatalysis, due to its unique properties. In this study, nano-PANI/N-TiO2 and nano-PANI/Ag-TiO2 photocatalytic composites were fabricated via aniline's oxidative polymerization, while the Ag-and N-chemically modified TiO2 nanopowders were synthesized through the sol-gel approach. All produced materials were fully characterized. Through micro-Raman and FT-IR analysis, the co-existence of PANI and chemically modified TiO2 particles was confirmed, while via XRD analysis the composites' average crystallite size was determined as ≈20 nm. The semi-crystal structure of polyaniline exhibits higher photocatalytic efficiency compared to that of other less crystalline forms. The spherical-shaped developed materials are innovative, stable (zeta potential in the range from -26 to -37 mV), and cost-effective, characterized by enhanced photocatalytic efficiency under visible light (energy band gaps ≈ 2 eV), and synthesized with relatively simple methods, with the possibility of recycling and reusing them in potential future applications in industry, in wastewater treatment as well as in biomedicine. Thus, the PANI-encapsulated Ag and N chemically modified TiO2 nanocomposites exhibit high degradation efficiency towards Rhodamine B dye upon visible-light irradiation, presenting simultaneously high biocompatibility in different normal cell lines.

Flexible and wearable battery-free backscatter wireless communication system for colour imaging

Wireless imaging, equipped with ultralow power wireless communications and energy harvesting (EH) capabilities, have emerged as battery-free and sustainable solutions. However, the challenge of implementing wireless colour imaging in wearable applications remains, primarily due to high power demands and the need to balance energy harvesting efficiency with device compactness. To address these issues, we propose a flexible and wearable battery-free backscatter wireless communication system specially designed for colour imaging. The system features a hybrid RF-solar EH array that efficiently harvests energy from both ambient RF and visible light energy, ensuring continuous operation in diverse environments. Moreover, flexible materials allow the working system to conform to the human body, ensuring comfort, user-friendliness, and safety. Furthermore, a compact design utilizing a shared-aperture antenna array for simultaneous wireless information and power transfer (SWIPT), coupled with an optically transparent stacked structure. This design not only optimizes space but also maintains the performance of both communication and EH processes. The proposed flexible and wearable systems for colour imaging would have potentially applications in environmental monitoring, object detection, and law enforcement recording. This approach demonstrates a sustainable and practical solution for the next generation of wearable, power-demanding devices.

Visible-light-responsive mesoporous PtO/2D YVO4 composite material for fostered photocatalytic hydrogen generation

Hydrogen (H2) is a significant alternative energy supply due to its outstanding and potentially useful properties, promoting sustainable development. Photocatalytic H2 generation from H2O employing inexhaustible and naturally abundant solar power on semiconducting photocatalysts is a promising and sustainable approach. Yet, particle aggregation/agglomeration, insufficient solar-light absorbance capacity, and quick photo-excited charge carriers’ recombination are the main deficiencies in most current photocatalytic systems. This investigation intends to fabricate mesoporous YVO4 nanosheets through a facile hydrothermal process, employing polyvinyl alcohol polymer as a structural directing agent to prevent agglomeration. Moreover, for the first time, varied tiny contents of platinum oxide (PtO) ranging from 0.3 to 1.2 wt%, were decorated on YVO4, constructing p-n PtO-YVO4 heterojunctions. The fabricated catalysts were characterized via advanced instruments and applied to H2 production using visible light energy. It was found that the physicochemical characteristics of the designed catalysts revealed the influence of loading PtO on the surface, structure, light absorbance features, charge separation, and efficacy. The loading of 0.9 wt% PtO on YVO4 has barely lowered the surface area (SA) from 187 to 176 m2/g. In contrast, the visible wavelength uptake is notably extended owing to the substantial energy bandgap narrowing from 3.40 to 2.11 eV. The visible-light-evolved hydrogen on 0.9 wt% PtO-YVO4 amounted to 34.76 mmol g−1. Moreover, this novel sample demonstrated a 99.88% recycling capacity after five cycles. This efficacious photocatalytic H2 generation is due to extensive light sensitivity and the rapid charge separation and migration between PtO and YVO4 following the p-n heterojunction mechanism.

Visible light-enhancing antibacterial ability of gold ions for its application of the prevention and treatment of dentin caries

To develop new antimicrobial strategy or agents has always been an eternal topic for the researchers. In this study, we have found that the visible light can enhance the antibacterial action of gold ions because of the photo-reduction and thus the visible light energy can be used to kill bacteria. The electron accepting ability of Au ions exposed to the visible light can strengthen, so their damage capability for the organic compounds from bacteria simultaneously enhances. The products of light-triggering Au ions, Au nanoparticles (Au NPs), also can bind protein and other bacterial cell wall components to further enhance the antibacterial ability. With the aid of the penetrating capacity of Au ions and light, light can also enhance the antibacterial action of Au ion in the biofilm and dentinal tubules and their products have the ability to crosslink the collagens to protect them from the degradation of collagenase. The toxicity of Au ions limits its application in clinic treatment, but the toxicity can decrease significantly after Au ions kills bacteria and the light can further reduce the toxicity as well. High concentration of Au ions and long-exposure light for dentin-pulp complex also are safe in vivo. Hence, light-enhancing the antibacterial treatment of Au ions has the potential to be used in the prevention and cure of the caries.

Investigation of high-pressure effect on the physical properties of FrNBr3 (N[dbnd]Ca, Sr) non-toxic halide perovskites

Utilizing ab-initio modeling, this study analyzes the possibility of replacing Lead with Francium halide perovskite for use in potential photovoltaic or optoelectronic device applications. Density functional theory is employed to estimate the structural, electronic, bonding, optical, anisotropic elastic, and mechanical characteristics of FrNBr3 (NCa, Sr) at various hydrostatic stresses scaling from 0 to 80 GPa. The calculation of the tolerance factor validates the structural stability. At 0 GPa pressure, the computed lattice constants for FrCaBr3 and FrSrBr3 are 5.78 Å (5.38 Å) and 6.03 Å (5.62 Å), respectively, using GGA (HSE03) approximation potential. FrNBr3 (NCa, Sr) perovskites show increased band gap values using the HSE03 method. Notably, these HSE03-derived values align with the trends observed in the GGA-PBE scheme, under both normal and hydrostatic pressure conditions. As pressure increases, both the lattice constant and unit cell volume decrease significantly. The estimated direct band gaps demonstrate the semiconducting nature of the compounds under ambient pressure. However, when pressure increases, the band gap narrows, increasing conductivity, and makes it as one of the great contenders of microelectronics as well as tandem photovoltaics due to its shift from ultraviolet to visible light energy region. Applying pressure enhances the optical properties, showcasing its utility in various semiconductor applications within the visible ranges and overcoming its limited usage in the ultraviolet domain. In the same vein, the application of hydrostatic pressure significantly impacts mechanical properties without compromising stability. The ductile and anisotropy character become more pronounced when pressure is exerted.

Light-Driven Purification of Progesterone from Steroid Mixtures Using a Photoresponsive Metal-Organic Capsule.

Chemical separations are expensive, consuming 10-15% of humanity's global energy budget. Many current separation methods employ thermal energy for distillation, often through the combustion of carbon-containing fuels, or extractions and crystallizations from organic solvents, which must then be discarded or redistilled, with a substantial energetic cost. The direct use of renewable energy sources, such as light, could enable the development of novel separations processes, as is required for the transition away from fossil fuel use. Metal-organic capsules, which can selectively bind molecules from mixtures, can provide the foundation for these novel separations processes. Here we report a tetrahedral metal-organic capsule bearing light-responsive diazo moieties around its metal-ion vertices. This capsule can be used to selectively separate progesterone from a mixture of steroids in a process driven by visible light energy. Our process combines biphasic extraction and selective binding of progesterone with the light-driven release of this molecule in purified form. Ultimately, our process might be adapted to the purifications of the many other fine chemical products that are bound selectively by capsules.

Toward Indoor Simulations of OPV Cells for Visible Light Communication and Energy Harvesting

Toward Indoor Simulations of OPV Cells for Visible Light Communication and Energy Harvesting