Effect Of Visible Light Irradiation Research Articles

Investigations of high-conductivity interfaces of ferroelectric/dielectric heterostructures

Conductive properties of film ferroelectric/dielectric heterostructures on MgO substrate in the wide temperature range were studied. The conditions influencing the occurrence of highly conductive layer at the interface of the Ba0.8Sr0.2TiO3/LaMnO3/Ba0.8Sr0.2TiO3/MgO heterostructure were considered. The effect of visible light irradiation on the electrical resistance of highly conductive layer at the heterointerfaces in Ba0.8Sr0.2TiO3/LaMnO3/Ba0.8Sr0.2TiO3/MgO and LaMnO3/Bi4Ti3O12/Ba0.4Sr0.6TiO3/MgO was observed. When exposed to light, an immediate increase in the resistance of a heterostructure occurred with full recovery in the dark state. A possible mechanism for this phenomenon was discussed.

Synergetic piezo-photocatalytic effect in NaNbO3/WO3 photocatalyst for RhB degradation

Improving the separation efficiency of photo-generated charge carriers is an important strategy to enhance the photocatalytic performance. In this paper, the NaNbO3/WO3 composite photocatalyst was prepared via a hydrothermal method, which exhibited a substantial increase in photocatalytic activity through the synergetic effect of visible light irradiation and ultrasound vibration. The XRD, FT-IR, Raman, SEM, XPS, UV–vis DRS, and photoluminescence spectroscopy results indicated that a large number of WO3 particles were tightly attached to the surface of NaNbO3 nanowires in the NaNbO3/WO3 composite catalyst. Under the piezo-photocatalysis condition, the degradation efficiency of Rhodamine B (RhB) by 5 % NaNbO3/WO3 was significantly improved, reaching 73.7 % within 120 min. Meanwhile, the piezo-photocatalytic degradation efficiency of the NaNbO3/WO3 composite catalyst was increased by 30.1 % compared to single photocatalysis, and the corresponding reaction rate constant (K) was 2.23 times than that of single photocatalysis. In addition, quenching tests showed that h+ was the primary active species in piezo-photocatalytic process. The significant enhancement of piezo-photocatalytic performance was attributed to the piezoelectric field caused by the bending deformation of the NaNbO3 nanowires, which was an important driving force for photo-generated charge carrier separation. Furthermore, the production of multiple redox active sites simultaneously improved the photocatalytic performance.

Production of an environmental friendly ultra-low sulfur diesel fuel under the effect of visible light irradiation using new nanocomposite based on BiFeO3/ BiOCl

The excessive use of fossil fuels raises SOX emissions, resulting in numerous negative consequences for the environment. Several technologies have been currently in use for the removal of sulfur compounds from diesel fuel feedstock. Among those, photocatalysis can be counted as one of the most promising routes for producing green diesel fuels. Nevertheless, introducing new structures for use as efficient photocatalysts is usually demanded. Thus, this research article presents BiFeO3/BiOCl nanocomposite as a novel photocatalyst with an improved electron–hole separation property for desulfurization under visible light. The structural characteristics of the prepared composite were verified through X-ray diffraction (XRD), Fourier transforms infrared (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and energetic dispersive X-ray (EDX). Surface properties of the synthesized nanocomposite were determined by BET nitrogen adsorption-desorption isotherm. The illustrated composite's surface and bulk morphologies were also gained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. UV–vis diffuse reflectance and photo-luminance (PL) were used to describe the optical features of a Bi-based photocatalyst. The prepared photocatalyst could show encouraging results in achieving a sulfur removal of 98.90% using a diesel feedstock has a sulfur content of 500 ppm. This desulfurization percentage was obtained through photo-oxidative route using hydrogen peroxide as an oxidant followed by a solvent extraction step using acetonitrile.

Mechanism of sulfur removal from high sulfur coal by visible light assisted oxidation system

ABSTRACT In order to investigate the effect of visible light irradiation on oxidative desulfurization. Three kinds of coals (SM, YYH and GZ) and four sulfur model compounds were selected as research objects. The effects of different irradiation time (30, 60, 90 and 120 min) and light source power (150, 220 and 300 W) of coal desulfurization were investigated. The samples before and after desulfurization were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The results show that when coal:H2O2 = 1:5 (g:mL), light source power is 220 W and irradiation is 60 min, the desulfurization rate of SM, YYH and GZ can reach the maximum, which were 27.97%, 56.28% and 66.22%, respectively. According to the characterization of samples before and after desulfurization, it was found that the low-valence sulfur changes into the high-valence sulfur with a more stable structure through a certain transition state during the desulfurization process. Coal responds to visible light, which can promote the generation of electron–hole pairs in the system, so as to enhance the oxidative desulfurization ability of the system. Visible light irradiation can promote the production of strong oxidation active group HO·, thereby improving the desulfurization rate of coal.

Visible Light Enhanced Electrocatalysis of Methanol Oxidation and Hydrogen Evolution on Nanoporous Nickel Hydroxide Film

In this work, high-surface-area nanoporous nickel hydroxide (Ni(OH)2) was one-pot electrodeposited by a dynamic hydrogen bubble template formed through facile water electrolysis. The as-obtained nanoporous Ni(OH)2 exhibited a visible light response semiconducting behavior with an optical band gap of 2.17 eV, as estimated by the Tauc methodology. The Mott-Schottky plot estimated the valence band (EVB) and conduction band (ECB) energies of the nanoporous Ni(OH)2 to −6.14 and −3.97 eV, respectively. The effects of visible light irradiation of nanoporous Ni(OH)2 film on methanol oxidation (MOR) and hydrogen evolution (HER) reactions were investigated in alkaline solutions. Compared to data obtained under dark, the potentiodynamic linear sweep voltammetry (LSV) and potentiostatic chronoamperometry (CA) results revealed remarkable enhancements in MOR and HER current responses using nanoporous Ni(OH)2 electrode under visible light, reaching up to 59% and 153%, respectively. The superior photoelectrochemical performances of the nanoporous Ni(OH)2 film toward MOR and HER were attributed to the high surface area, narrow band gap, low electron/hole recombination, and elevated light absorption efficiency induced by multiple reflection and scattering of incident light. In sum, the high photoelectrocatalytic performances of the nanoporous Ni(OH)2 combined with the low material cost and facile production make it promising for various electrochemical reactions with better reaction rates under visible light irradiation.

Bifunctional PVA/ZnO/AgI/Chlorophyll Nanocomposite Film: Enhanced Photocatalytic Activity for Degradation of Pollutants and Antimicrobial Property under Visible-Light Irradiation.

Here, poly(vinyl alcohol) (PVA) with numerous hydroxyl groups has been applied as a suitable substrate for efficient formation of zinc oxide (ZnO) nanoparticles with a flower shape (confirmed by electron-scanning microscopy), silver iodide (AgI) nanoparticles, and chlorophyll (Chl), as a natural-based photocatalyst (PVA/ZnO/AgI/Chl). First, an efficient preparation route for the PVA/ZnO/AgI/Chl nanophotocatalyst is presented starting from the extraction of Chl from fresh spinach. Then, the catalytic role of the prepared composite is precisely investigated in degradation of methylene blue (MB). The effects of visible-light irradiation, different contact times, and the employed ingredients on the architecture of the PVA/ZnO/AgI/Chl are screened in the degradation process of MB. It is demonstrated that the best result (MB removal efficiency ca. 95.5%) is achieved by applying the visible-light irradiation using a LED lamp (70 W, λ = 425 nm) for a 60 min duration. Moreover, the photocatalytic performance of PVA/ZnO/AgI/Chl has been further confirmed by degradation of Congo red (CR) (ca. 92%, in 150 min) and 4-chlorophenol (4-CP) (88%, in 270 min), as well. As another function of the prepared PVA/ZnO/AgI/Chl composite, a substantial antibacterial property against human bacterial pathogens such as Staphylococcus aureus and Escherichia coli as Gram-positive and Gram-negative bacteria has been noticed, studied by agar diffusion cup plate and colony methods. The zones of inhibition have been evaluated ca. 20 and 12 mm for the S. aureus and E. coli cell lines, respectively. Finally, a great synergy between the prepared composite and the visible light has been observed through the examination of the live bacteria: 99.6% for S. aureus and 99.8% for E. coli in the presence of visible light, after the subjection of PVA/ZnO/AgI/Chl particles to the bacteria, verified by the colony counter method.

Visible-light-assisted efficient removal of sulfur from high sulfur coal under mild conditions

ABSTRACT In order to find a green and effective chemical desulfurization method, the photocatalytic technology and oxidative desulfurization were combined to minimize the sulfur content in coals. In this paper, 30% H2O2 was mixed with raw coal, demineralized coal, and removal pyrite coal at a ratio of 5:1 (ml: g), the oxidative desulfurization reaction was carried out with visible light irradiation for different times, and compared with the experimental results without light irradiation under the same condition. IC was used to characterize the SO4 2- content in the filtrate of the reaction mixture, and the chemical method was used to determine the forms of sulfur in coal samples before and after desulfurization, FTIR was used to characterize the change of sulfur-containing functional group content in coal samples before and after desulfurization. And the photochemical characterization of raw coal, demineralized coal and removal pyrite coal were carried out to explore the photochemical properties of different coal samples, further explored the reasons for the promoting effect of visible light irradiation on H2O2 oxidation desulfurization. The experimental results showed that the desulfurization efficiency can be significantly enhanced by visible light irradiation. Under the optimum conditions, the desulfurization rate can reach 67.68%, most of the pyrite and part of organic sulfur in coals were effectively removed. The pyrite in coal was the main reason for the promotion of H2O2 oxidative desulfurization by visible light irradiation.

Application of a Photocatalyst as an Inactivator of Bovine Coronavirus.

Bovine coronavirus (BCoV), a major causative pathogen of bovine enteric and respiratory diseases and a zoonotic pathogen transmissible between animals and humans, has led to severe economic losses in numerous countries. BCoV belongs to the genus Betacoronavirus, which is a model of a pathogen that is threatening human health and includes severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-2, and Middle East respiratory syndrome coronavirus. This study aimed to determine whether photocatalytic material effectively reduces CoVs in the environment. Using the film adhesion method of photocatalytic materials, we assessed its antiviral activity and the effect of visible light irradiation according to methods defined by the International Organization for Standardization. Consequently, photocatalytic material was found to have antiviral activity, reducing the viral loads by 2.7 log TCID50 (tissue culture infective dose 50)/0.1 mL (500 lux), 2.8 log TCID50/0.1 mL (1000 lux), and 2.4 log TCID50/0.1 mL (3000 lux). Hence, this photocatalytic material might be applicable not only to reducing CoVs in the cattle breeding environment but also perhaps in other indoor spaces, such as offices and hospital rooms. To our knowledge, this study is the first to evaluate the antiviral activity of a photocatalytic material against CoV.

Effect of visible light irradiation on catalytic activity of gold nanoparticles and perylene adsorbed on silica gel

A novel visible-light-responsive photocatalyst consisting of gold nanoparticles and perylene adsorbed on silica gel (Au/Pe/SiO2) has been developed. By comparing the reduction of an environmental pollutant in the presence of Au/Pe/SiO2 and sodium borohydride by visible light irradiation to that in the dark, the effect of the photocatalyst on the catalytic activity of AuNP was observed. Visible light irradiation of the p-nitrophenol (p-NP) aqueous solution in the presence of sodium borohydride and Au/Pe/SiO2 resulted in the acceleration of the decomposition of p-NP. The rate constant for the reaction with the irradiation was 2.1 times higher than that in the dark.

Acceleration effect of the forensic luminol reaction induced by visible light irradiation of whole human blood aqueous solutions

The first quantitative study on the effect of visible light irradiation on the luminol reaction, used forensically, was conducted using whole human blood aqueous solutions (hemolytic state) and an LED lamp. Whole human blood aqueous solutions under an air atmosphere were irradiated with visible light, resulting in the maximum chemiluminescence (CL) intensity (@ 440 nm) increasing about 1.7-fold due to acceleration of the luminol reaction rate. No acceleration effect was observed under an argon (Ar) atmosphere, or under an air atmosphere in the presence of sodium azide (NaN3; a scavenger of singlet oxygen (1O2)). Furthermore, no conversion from Fe(II) hemoglobin to Fe(III) hemoglobin (methemoglobin) was observed in the absorption spectrum following irradiation. We suggest that these effects are due to easier approach of the luminol reagents to heme following damage of the globin protein around the heme, or damage to the red blood cell membrane, induced by 1O2 generated by an excited state of heme.

Effect of visible light irradiation on hydrogen production by CoNi2S4/CdWO4 controllable flower spherical photocatalyst

The CoNi2S4/CdWO4-3 (CNS/CW-3) was an excellent photocatalyst for hydrogen evolution. The controlled morphology of CNS/CW-3 was successfully by adding thiourea as sulfur source and TBA to control the CoNi2S4 nanoparticles. The photocatalytic hydrogen evolution activity of CoNi2S4 and CdWO4 under visible light irradiation was studied with different CoNi2S4 incorporation ratios. UV–vis absorption spectra showed that the absorbance of CNS/CW-3 composite catalyst increased significantly after doping CoNi2S4. The electrochemical and photoelectrochemical experiments also showed that the charge separation and electron transfer efficiency were higher when CoNi2S4 was attached to CdWO4. CNS/CW-3 exhibited excellent photocatalytic activity for hydrogen evolution under visible light irradiation. Its hydrogen evolution activity reached 269.08 μmol in 5 h, and had good light stability. It was a potential strategy to design photocatalyst with controllable morphology.

The comprehensive effects of visible light irradiation on silver nanowire transparent electrode

The silver nanowire (AgNW) transparent electrode is one of the promising components for flexible electronics due to its high electrical and thermal conductivity, optical transparency and flexibility. However, the application of the AgNW electrode with an improved performance is generally limited by its poor long-term stability. As the name suggests, the transparent electrode is usually exposed to visible light in various applications. Unlike other electrode materials, AgNWs show unique and complicated behavior under long-term visible light illumination. In this study, the comprehensive effect of visible light irradiation on the AgNW transparent electrode is initially investigated in detail. Light irradiation induces the migration of silver to enhance the nanowire contacts while also leading to the generation and growth of particles and diameter loss in the nanowire. Light irradiation accelerates the sulfidation and oxidation of the AgNWs as well, resulting in the emergence of degradation products on the nanowire surface. All these effects influence the sheet resistance of the AgNW electrode during light illumination. The light-induced change of sheet resistance also relates to the nanowire concentration due to the sensitivity of the wire–wire contact resistance near the percolation threshold. It is believed that this work will be a valuable reference for the design, processing and application of transparent electrodes used in numerous optoelectronic devices.

Debridement of Bacterial Biofilms with TiO2/H2O2 Solutions and Visible Light Irradiation.

Objectives The aim of the study was to explore the debridement efficacy of different solutions of H2O2 and rutile particles against Staphylococcus epidermidis and Pseudomonas aeruginosa biofilms attached to titanium surfaces when exposed to visible light. Materials and Methods Titanium discs cultivated with biofilms of Staphylococcus epidermidis or Pseudomonas aeruginosa were subjected for 1 min to suspensions consisting of rutile particles mixed with high (950 mM) or low (2 mM) concentrations of H2O2 under visible light irradiation (405 nm; 2.1 mW/cm2). Discs were rinsed and the degree of debridement was determined through scanning electron microscopy and viability assessment of the remaining bacteria using luminescence measurements and/or a metabolic activity assay. Results Cleaning mixtures containing the higher concentration of H2O2 showed a significantly improved debridement compared to the negative control in all experiments. The addition of rutile particles was shown to have a statistically significant effect in one test with S. epidermidis. Limited evidence of the catalytic effect of visible light irradiation was seen, but effects were relatively small and statistically insignificant. Conclusions H2O2 at a concentration of 950 mM proved to be the strongest contribution to the debridement and bactericidal effect of the cleaning techniques tested in this study.

ChemInform Abstract: Visible‐Light‐Mediated Facile Reductive Aromatization of Quinols.

A range of phenols bearing multiple useful functionalities at their meta positions were prepared from the corresponding quinols under the cooperative effects of visible light irradiation, Ru(bpy)3Cl2 photosensitizer, Hunig’s base, LiBF4, and MeCN solvent. The process involves visible-light-enabled photocatalytic cleavage of C–O bond as the strategic event.

Visible-Light-Mediated Facile Reductive Aromatization of Quinols

A range of phenols bearing multiple useful functionalities at their meta positions were prepared from the corresponding quinols under the cooperative effects of visible light irradiation, Ru(bpy)3Cl2 photosensitizer, Hunig’s base, LiBF4, and MeCN solvent. The process involves visible-light-enabled photocatalytic cleavage of C–O bond as the strategic event.

Genotoxic effects of camphorquinone and DMT on human oral and intestinal cells

ObjectiveReleased components of oral biomaterials can leach into the oral cavity and may subsequently reach the gastrointestinal tract. Camphorquinone (CQ) is the most common used photoinitiator in resinous restorative materials and is often combined with the co-initiator N,N-dimethyl-p-toluidine (DMT). It has been shown that CQ exerts cytotoxic effects, at least partially due to the generation of reactive oxygen species (ROS). Objective of this study was to examine the cytotoxic and genotoxic potential of CQ in human oral keratinocytes (OKF6/TERT2) and immortalized epithelial colorectal adenocarcinoma cells (Caco-2). Furthermore, the effects of visible-light irradiation and the co-initiator DMT were investigated as well as the generation of ROS, the potential protective effect of glutathione (GSH) and a recovery period of CQ-treated Caco-2 cells. MethodsThe alkaline comet assay was used to determine DNA damage. Additionally, an enzyme modified comet assay was applied, which detects 7,8-dihydro-8-oxoguanine (8-oxoguanine), a reliable marker for oxidative stress. ResultsOur data revealed that high concentrations of CQ induced DNA lesions in OKF6/TERT2 cells. This DNA damage is at least partly caused by the generation of 8-oxoguanine. In addition, CQ and DMT increased ROS formation and induced DNA damage in Caco-2 cells. CQ-treatment resulted in generation of 8-oxoguanine. The antioxidant GSH efficiently prevented CQ-associated DNA damage. Furthermore, a recovery following CQ-treatment significantly reduced DNA damage. SignificanceWe conclude that CQ-induced DNA damage is caused by oxidative stress in oral and intestinal cells. These lesions can be prevented and possibly repaired by GSH-treatment and recovery of cells after the photoinitiator is removed from cultures.

Anti-inflammatory effects of green soybean extract irradiated with visible light.

We conducted a preliminary investigation of the effects of visible light irradiation on plant extracts, and we observed a strong suppressive effect on interleukin (IL) 2 expression with the inhibition of c-Jun amino-terminal kinase (JNK) phosphorylation in Jurkat cells by visible light irradiation to ethanol extract from green soybeans (LIEGS). This effect was produced only by extracts from green soybeans (Glycine max) and not other-color soybeans. LIEGS suppressed the lipopolysaccharide-induced IL-6, IL-12 and TNF-α expression levels in human monocyte THP-1 cells in a concentration-dependent manner. LIEGS was applied for 8 weeks to NC/Nga mice. LIEGS suppressed the development of atopic dermatitis (AD)-like skin lesions and reduced the dermatitis scores of the mice. The light irradiation changed the various types of small-molecule compounds in extracts. Visible light irradiation to daidzein with chlorophyll b induced a novel oxidative product of daidzein. This product suppressed IL-2 expression in Jurkat cells.

青大豆抽出物の機能性について

Hot water extracts of green soybean, Glycine max (WEGS) significantly decreased the levels of ovalbumin (OVA)-specific IgE in mice and significantly suppressed toluene diisocyanate-induced nasal mucosa secretion. An open-label human pilot study including 16 subjects with Japanese cedar pollinosis (JCP) was conducted. The symptom scores for JCP were better in the long-term WEGS intake group than in the short-term intake group. WEGS have great potential as an orally active immune modulator for the treatment of various allergic diseases. We conducted a preliminary investigation of the effects of visible light irradiation on plant extracts, and observed a strong suppressive effect on interleukin (IL)-2 expression in Jurkat cells following treatment with visible light-irradiated ethanol extract from green soybeans (LIEGS). This effect was produced only by extracts from green soybeans and not soybeans of other colors. LIEGS suppressed lipopolysaccharide-induced IL-6, IL-12, and TNF-α expression levels in human monocyte THP-1 cells in a concentration-dependent manner. LIEGS suppressed the development of atopic dermatitis-like skin lesions and reduced the dermatitis scores of NC/Nga mice.

Effects of heat treatment and visible light exposure on the oxidative stability of rice bran and of rice bran oil

Rice bran was heated at 120°C for 0 to 30 min to extend the oxidative stability. Also, effects of visible light irradiation on the crude rice bran oil (RBO) from rice bran heated at 120°C for 20 min were studied. As heat treatment time increased from 0 to 30 min, rice bran had significantly high oxidative stability at 40°C for 12 days (p 0.05). Results of acid value and conjugated dienoic acid (CDA) confirmed the higher oxidative stability of heat treated rice bran. γ-Oryzanol content was not significantly different among crude RBO during heat treatment and storage (p>0.05). Visible light irradiation caused similar degree of lipid oxidation in crude RBOs from rice bran irrespective of heat stabilization for 48 h, which may be due to the presence of photosensitizers in crude RBO like chlorophylls. This study showed that heat treatment was not effective to enhance the oxidative stability of RBO under visible light irradiation and products containing rice bran should be stored in the dark conditions.

Effects of visible light irradiation on the oxidative stability in rice bran

Raw rice bran was treated with or without visible light exposure at room temperature or stored at 40 °C in the dark for 10 days and rice bran oil (RBO) was recovered from each rice bran. Headspace oxygen content from rice bran and conjugated dienoic acid (CDA) value, acid value, content of γ-oryzanol, and fluorescence intensity in RBO were analyzed to determine the effects of visible light on the oxidative stability in rice bran. Headspace oxygen content in visible light irradiated rice bran (RBL) decreased by 12.8% for 10 days while those in the dark (RBD) and stored at 40 °C (RBT) decreased by 5.87 and 5.35%, respectively, implying visible light irradiation accelerates the consumption of oxygen. CDA values in RBO from RBL were significantly higher than those in RBO from RBD and RBT (p < 0.05). However, acid values in RBO were not significantly different among samples (p > 0.05). Both γ-oryzanol content and fluorescence intensity in RBO from RBL were significantly lower than those in RBO from RBD and RBT (p < 0.05). Fluorescence intensity, which is related to the content of chlorophylls, decreased in samples under light only, implying that chlorophyll photosensitization may play important roles in the acceleration of lipid oxidation in rice bran.