Low Power LED Research Articles

Tubular nanofiber membranes combined with Z-scheme CuS@Co3S4 heterojunction catalyst for high-efficient removal of polyvinyl alcohol from waste water with high COD

Polyvinyl alcohol (PVA), a typical water-soluble polymer with huge global production, is becoming one of the most ubiquitous pollutants and indeed the villain of the piece contributing high chemical oxygen demand (COD) in wastewater. Membrane technology is an effective method for wastewater purification, in particular, with the combination of peroxymonosulfate (PMS)-assisted advanced oxidation or photocatalytic process, is capable of maintaining high water flux and anti-fouling. Herein, a ZIF-67 derived Z-scheme CuS@Co3S4 heterojunction catalyst immobilized by poly (m-phenylene isophthalamide) (PMIA) tubular nanofiber membrane (CuS@Co3S4/PMIA-TNM) is designed using a polyester braided tube as interior reinforcement. The resultant membrane features with outstanding superhydrophilicity and commendable porosity (82.1%), leading to a significantly enhanced permeability (water flux > 82.3L·m-2·h-1). Meanwhile, the membrane shows promising PVA removal efficiency (> 99.9%) with a high COD removal efficiency (~ 83.4%) and enhanced antifouling capacity (flux recovery ratio > 99.7%) with the assistance of PMS driven by an ultra low-power LED lamp. The universal applicability and environmental adaptability are also verified in various reaction conditions. In terms of ecotoxicological impacts of the PVA wastewater before and after treatment on aquatic organisms, Zebrafish embryonic development dynamically demonstrated that the treated PVA waste water by the developed hybrid membrane is healthy for fish to grow. Our study definitely opens up a new avenue to develop high-performance catalytic membranes for PVA-based wastewater treatment.

Chlorin e6-Loaded Nanostructured Lipid Carriers Targeted by Angiopep-2: Advancing Photodynamic Therapy in Glioblastoma.

Glioblastoma (GBM) is a highly aggressive brain tumor known for its resistance to standard treatments. Despite surgery being a primary option, it often leads to incomplete removal and high recurrence rates. Photodynamic therapy (PDT) holds promise as an adjunctive treatment, but safety concerns and the need for high-power lasers have limited its widespread use. This research addresses these challenges by introducing a novel PDT approach, using chlorin e6 (Ce6) enclosed in nanostructured lipid carriers (Ang-Ce6-NLCs) and targeted to GBM with the angiopep-2 peptide. Remarkably, a single 5-min irradiation session with LEDs at 660nm and low power density (10mW cm- 2) proves effective against GBM, while reducing safety risks associated with high-power lasers. Encapsulation improves Ce6 stability and performance in physiological environments, while angiopep-2 targeting enhances delivery to GBM cells, maximizing treatment efficacy and minimizing off-target effects. The findings demonstrate that Ang-Ce6-NLCs-mediated PDT brings about a significant reduction in GBM cell viability, increases oxidative stress, reduces tumor migration, and enhances apoptosis. Overall, such treatment holds potential as a safe and efficient intraoperative removal of GBM infiltrating cells that cannot be reached by surgery, using low-power LED light to minimize harm to surrounding healthy tissue while maximizing tumor treatment.

Experimental investigation of polymeric straight fin heat sink for low power LED

Experimental investigation of polymeric straight fin heat sink for low power LED

Efficient photocatalytic decomposition of PFOA over BiOI1-x with low power LED light

In recent years, the academic community has shown significant interest in per- or polyfluoroalkyl compounds (PFAS) due to their challenging degradation and potential health risks. Photocatalysis has been investigated for PFAS decomposition due to its environmentally friendly nature. In this study, BiOI with abundant iodine vacancies was synthesized through solvothermal and calcination methods (referred to as BiOI1-x), and was used for PFAS degradation with a low power UV light source. Compared to pure BiOI, BIOI1-x showed higher photocatalytic activity towards PFOA (perfluorooctanoic acid). Within 5 h under 5 W LED light irradiation, the degradation rate of PFOA reached 51.9 % with BiOI1-x calcined at 440 °C (No significant degradation of PFAS was observed with pure BiOI). Capture experiments, electron paramagnetic resonance spectroscopy, and electrochemical experiments revealed that the main active species in the system were photogenerated holes, followed by hydroxyl radicals. Furthermore, the presence of iodine vacancies significantly improved the efficiency of charge carrier separation and enhanced the photocatalytic performance. Finally, a hypothetical degradation pathway for PFOA in this system was suggested. This study achieved efficient degradation of PFAS under low power LED light (5 W), emphasizing its significant practical importance in terms of energy conservation.

Degradation of tetracycline under a wide pH range in a heterogeneous photo bio-electro-fenton system using FeMn-LDH/g-C3N4 cathode: Performance and mechanism

The widespread use of antibiotics and the inefficiency of traditional degradation treatments pose threats to the environment and human health. Previous studies have reported the potential of bio-electro-Fenton (BEF) processes for antibiotic removal. However, some drawbacks, such as a strict pH range of 2–3 and iron sludge generation, limit their large-scale application. Thus, to overcome the narrow pH range of traditional BEF processes, a photo-BEF (PBEF) system was established using a novel FeMn-layered double hydroxide (LDH)/graphitic carbon nitride (g-C3N4) (FM/CN) composite cathode. The performance of the PBEF system was investigated by degrading tetracycline (TC) under low-power LED lamp irradiation. The results indicated that the pH range of the PBEF system could be expanded to 3–11 using an FM/CN cathode, which exhibited a TC removal efficiency of 63.0%–75.9%. The highest TC removal efficiency was achieved at pH 7. The efficient mineralization of TC by the PBEF system can be high, up to 67.6%. In addition, the TC removal mechanism was discussed in terms of reactive oxygen species, TC degradation intermediate analyses, and density functional theory (DFT) calculations. Strong oxidative hydroxyl radicals (·OH) were the dominant reactive oxidizing species in the PBEF system, followed by ·O2− and h+. Three pathways of TC degradation were proposed based on the analysis of intermediates, and the reactive sites attacked by electrophilic reagents were explored using DFT modeling. In addition, the overall toxicity of TC degradation intermediates effectively decreased in the PBEF system. This work offers deep insights into the TC removal mechanisms and performance of the PBEF system over a wide pH range of 3–11.

Third-Generation Anticancer Photodynamic Therapy Systems Based on Star-like Anionic Polyacrylamide Polymer, Gold Nanoparticles, and Temoporfin Photosensitizer.

Photodynamic therapy (PDT) is a non-invasive anticancer treatment that uses special photosensitizer molecules (PS) to generate singlet oxygen and other reactive oxygen species (ROS) in a tissue under excitation with red or infrared light. Though the method has been known for decades, it has become more popular recently with the development of new efficient organic dyes and LED light sources. Here we introduce a ternary nanocomposite: water-soluble star-like polymer/gold nanoparticles (AuNP)/temoporfin PS, which can be considered as a third-generation PDT system. AuNPs were synthesized in situ inside the polymer molecules, and the latter were then loaded with PS molecules in an aqueous solution. The applied method of synthesis allows precise control of the size and architecture of polymer nanoparticles as well as the concentration of the components. Dynamic light scattering confirmed the formation of isolated particles (120 nm diameter) with AuNPs and PS molecules incorporated inside the polymer shell. Absorption and photoluminescence spectroscopies revealed optimal concentrations of the components that can simultaneously reduce the side effects of dark toxicity and enhance singlet oxygen generation to increase cancer cell mortality. Here, we report on the optical properties of the system and detailed mechanisms of the observed enhancement of the phototherapeutic effect. Combinations of organic dyes with gold nanoparticles allow significant enhancement of the effect of ROS generation due to surface plasmonic resonance in the latter, while the application of a biocompatible star-like polymer vehicle with a dextran core and anionic polyacrylamide arms allows better local integration of the components and targeted delivery of the PS molecules to cancer cells. In this study, we demonstrate, as proof of concept, a successful application of the developed PDT system for in vitro treatment of triple-negative breast cancer cells under irradiation with a low-power LED lamp (660 nm). We consider the developed nanocomposite to be a promising PDT system for application to other types of cancer.

Label- and Reagent-Free Optical Sensor for Absorption-Based Detection of Urea Concentration in Water Solutions.

Contactless and label-free detection of urea content in aqueous solutions is of great interest in chemical, biomedical, industrial, and automotive applications. In this work, we demonstrate a compact and low-cost instrumental configuration for label-free, reagent-free, and contactless detection of urea dissolved in water, which exploits the absorption properties of urea in the near-infrared wavelength region. The intensity of the radiation transmitted through the fluid under test, contained in a rectangle hollow glass tubing with an optical pathlength of 1 mm, is detected in two spectral bands. Two low-cost, low-power LEDs with emission spectra centered at λ = 1450 nm and λ = 2350 nm are used as readout sources. The photodetector is positioned on the other side of the tubing, in front of the LEDs. The detection performances of a photodiode and of a thermal optical power detector have been compared, exploiting different approaches for LED driving current modulation and photodetected signal processing. The implemented detection system has been tested on urea-water solutions with urea concentrations from 0 up to 525 mg/mL as well as on two samples of commercial diesel exhaust fluid ("AdBlue™"). Considering the transmitted intensity in presence of the urea-water solution, at λ = 1450 nm and λ = 2350 nm, normalized to the transmitted intensity in presence of water, we demonstrate that their ratio is linearly related to urea concentration on a wide range and with good sensitivity.

Time-gated multi-dimensional luminescence thermometry via carbon dots for precise temperature mobile sensing.

Luminescence thermometry presents precise remote temperature measurement capabilities but faces significant challenges in real-world applications, primarily stemming from the calibration's susceptibility to environmental factors. External factors can compromise accuracy, necessitating resilient measurement protocols to ensure dependable temperature (T) readings across various settings. We explore a novel three-dimensional (3D) approach based on time-gated (t) luminescence thermometric parameters, Δ(T,t), employing physical mixtures of surface-engineered carbon dots (CDs) based on dibenzoylmethane and rhodamine B. These CDs showcase enduring, temperature-responsive, and customizable phosphorescence, easily activated by low-power LEDs and distinguished by their prolonged emission time due to thermally activated delayed phosphorescence. Quantifying the thermal emission dependency is achievable through conventional spectrometer analyses or by capturing photographs with a smartphone's camera under flashlight illumination, yielding up to 30 time-gated ratiometric thermometric parameters per sample. Notably, within the temperature range of 23-45 °C, the maximum relative sensitivity of 7.9% °C-1 surpasses current state-of-the-art CD-based thermometers and ensures temperature readout with low-resolution portable devices as non-modified smartphones.

CoO/NiFe LDH heterojunction as a photo-assisted electrocatalyst for efficient oxygen evolution reaction

Photo-assisted electrocatalysis is a frontier direction of electrocatalysis in recent years, which is based on the synergistic effects of electrical and optical energy, providing a new strategy to improve the oxygen evolution reaction (OER) performance. The development of photo-assisted electrocatalysts for OER with high activity and long-term stability is of great significance for hydrogen production through water splitting. In this work, the CoO/NiFe LDH heterojunction are prepared as a photo-assisted electrocatalysts for the first time to enhance OER performance. The strong electron coupling between CoO and NiFe LDH is beneficial to change the electronic structure of catalyst and promote OER. Meanwhile, under illumination, NiFe LDH suppresses the photogenerated charge recombination of CoO and accelerates the charge transfer to promote the accumulation of holes in the CoO valence band, which can be used to further improve its OER performance. The CoO/NiFe LDH requires only an overpotential of 230 mV to achieve 10 mA cm−2 under illumination, which is 60 mV lower than that without irradiation. For water splitting, CoO/NiFe LDH heterojunction only requires 1.57 V (without light) and 1.52 V (with light) to achieve 10 mA cm−2, which is superiors to RuO2 and most NiFe LDH based materials. Even under the irradiation of low-power LED strip, the CoO/NiFe LDH can still exhibit excellent water splitting performance and long-term stability. This work adopts a promising photo-assisted electrocatalytic strategy to promote the efficiency of water splitting, and boosts the development of LDH-based two-dimensional materials in the field of photo-assisted electrocatalysis.

Nonlinear Loads in Lighting Installations—Problems and Threats

Distorted currents drawn by nonlinear loads used in power installations (including lighting) can cause many problems. With the constantly progressing increase in the number of these loads, these phenomena can accumulate, constituting significant causes of serious failures in both electrical and electronic devices, as well as installation components. The effects of disturbances introduced to the network by nonlinear loads may include, for example, line overloads, overheating of transformers and motors, capacitor failures, accelerated degradation of insulation, etc. The article presents examples of measurement results for luminaires with discharge and LED sources. Measurements of the electrical parameters of a three-phase outdoor lighting installation consisting of luminaires with low-power LED sources and luminaires with discharge sources are also discussed. Based on the recorded waveforms, the measurement results were determined. High harmonic values for the phase currents and the current in the neutral conductor were recorded. The results of measurements of the parameters of LED luminaires with control systems, the operation of which causes excessive heat generation, are presented. The methodology for cable selection in circuits with current harmonics is described.

Superlattice Nanofilm on a Touchscreen for Photoexcited Bacteria and Virus Killing by Tuning Electronic Defects in the Heterointerface.

Currently, the global COVID-19 pandemic has significantly increased the public attention toward the spread of pathogenic viruses and bacteria on various high-frequency touch surfaces. Developing a self-disinfecting coating on a touchscreen is an urgent and meaningful task. Superlattice materials are among the most promising photocatalysts owing to their efficient charge transfer in abundant heterointerfaces. However, excess electronic defects at the heterointerfaces result in the loss of substantial amounts of photogenerated charge carrier. In this study, a ZnOFe2 O3 superlattice nanofilm is designed via atomic layer deposition for photocatalytic bactericidal and virucidal touchscreen. Additionally, electronic defects in the superlattice heterointerface are engineered. Photogenerated electrons and holes will be rapidly separated and transferred into ZnO and Fe2 O3 across the heterointerfaces owing to the formation of ZnO, FeO, and ZnFe covalent bonds at the heterointerfaces, where ZnO and Fe2 O3 function as electronic donors and receptors, respectively. The high generation capacity of reactive oxygen species results in a high antibacterial and antiviral efficacy (>90%) even against drug-resistant bacteria and H1N1 viruses under simulated solar or low-power LED light irradiation. Meanwhile, this superlattice nanofilm on a touchscreen shows excellent light transmission (>90%), abrasion resistance (106 times the round-trip friction), and biocompatibility.

Front Cover: Gold Nanoparticles‐Titania Heterojunction: Photoelectrochemical Detection of Ciprofloxacin (ChemElectroChem 8/2023)

The Front Cover shows the photoelectrochemical sensor prepared by covering gold nanoparticles (AuNPs) with a thin layer of TiO2. The obtained hybrid material, which exploits synergistically the properties of its components, was used to monitor ciprofloxacin, exhibiting a response only once irradiated. Good performances were obtained using a low-power LED. Such discovery may pave the way for future in situ applications in environmental monitoring. More information can be found in the Research Article by D. Fumagalli et al.

Boosted Light-Excited NO2 Detection Based on Hierarchical Z-Scheme MoS2/SnO2 Heterostructure Microspheres at Room Temperature

Light excitation has been developed as an economical way to realize room-temperature gas sensing recently. However, the high recombination rate of photogenerated carriers in semiconductor gas sensing materials leads to very limited carriers that can effectively take part in sensing reactions, which greatly restricts the further performance improvement of gas sensing under light excitation. Here, a hierarchical Z-scheme heterostructure microsphere of MoS2/SnO2 is designed and prepared. The heterostructure demonstrates an outstanding NO2 sensing performance at room temperature with the excitation of a low-power LED light (0.06 W), which exhibits an ultrahigh sensitivity of 264.2 to 10 ppm of NO2 along with acceptable response/recovery properties. The physical mechanism of NO2 sensing is analyzed. The results suggest that the construction of the Z-scheme heterostructure between MoS2 and SnO2 can greatly promote the separation of photogenerated carriers so that more photogenerated carriers can take part in the NO2 sensing reaction. Furthermore, the designing of a hierarchically porous structure can provide abundant active sites for gas sensing reactions. The work not only expands the development of Z-scheme heterostructures in gas sensing but also provides a strategy to promote the performance of light-excited gas sensors by designing a Z-scheme heterostructure with a hierarchically porous structure.

The NH2-UiO-66/3,4,9,10-perylenetetracarboxylicdiimide for Cr(VI) reduction: DFT calculation, performance, and mechanism

The composite molecular structure model of NH2-UiO-66/PDINH (UiOxPDy) constructed from NH2-UiO-66 and PDINH (3,4,9,10-perylenetetracarboxylicdiimide) was built to conduct density functional theory (DFT) calculations for predicting the heterojunction type and corresponding Cr(VI) reduction reaction mechanism. The results of DFT calculations illustrated that Z-scheme heterojunction interface was inclined to form between NH2-UiO-66 and PDINH via automatically matching the dominant crystal plane, which was in consistent with the results of X-ray photoelectron spectroscopy. Subsequently, the Z-scheme heterojunction UiOxPDy composites (x, y represented the mass of NH2-UiO-66 and PDINH, respectively) were fabricated via ball-milling treatment, which were used to accomplish effective photocatalytic Cr(VI) reduction under low power LED visible light. The as-prepared optimal UiO125PD75 composite demonstrated good stability and reuse performance in the five runs’ successive operations. The corresponding Cr(VI) reduction mechanism over UiO125PD75 was verified with the aid of electrochemical test, radical scavenging experiments and electron spin resonance.

Photocatalytic Cr(VI) reduction over MIL-88A(Fe) on polyurethane sponge: From batch to continuous-flow operation

MIL-88A(Fe)@sponge (MS) was synthesized by a dip-coating method, which displayed efficient photocatalytic Cr(VI) reduction efficiency under both low power LED UV light and real solar light irradiation. It was observed that MS (0.2 g/L) could remove 100% Cr(VI) (10 mg/L) by adding 0.4 mmol/L tartaric acid (TA) without adjusting pH (pH 5.05) within 6.0 min and 3.0 min under UV light and real solar light irradiation, respectively. Besides, the photo-induced e− and radicals (O2•− and CO2•−) were found to play the momentous roles in the MS/TA/UVL/Cr(VI) system by the scavenger experiments and electron spin resonance (ESR) tests. MS was also filled into a fixed-bed reactor to test the possibility of long-term Cr(VI) reduction operation in TA/UVL system. As expected, the results revealed that MS could still maintain 100% activity up to 60 h. These results demonstrated that MIL-88A(Fe) might be the potentially efficient catalyst for large-scale wastewater treatment in the near future.

Low power LED assisted effective photodegradation of cationic and anionic dyes by zinc phthalocyanine based 2D polyamide sensitized CuO photocatalyst

The present investigation details the synthesis and photocatalytic performance of an organic-inorganic hybrid system involving phthalocyanine-based 2D polyamide sensitized CuO photocatalyst in the presence of low-power LED visible light. Zinc phthalocyanine-based 2D polyamide (2D-ZnPcPA), CuO nanomaterial and their nanocomposites (2D-ZnPcPA@CuO) were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) to understand the structure, size, morphology and optical properties. To examine the photodegradation capability of newly synthesized photocatalysts in the presence of the low-power white LED (16 W) as a source of visible light, cationic methylene blue (MB) and anionic congo red (CR) dyes were employed as modular pollutants. The impact of different parameters on photocatalytic activity such as photocatalyst dosage, contact time, pH of dye solution and photocatalyst re-usage, is examined. The results indicate that photosensitizing CuO with 2D-ZnPcPA improved photocatalytic performance for the photodegradation of MB and CR dyes substantially. The removal effectiveness of MB and CR under optimised conditions was determined to be greater than 96 and 93% in 90 minutes respectively.

High N‐H Photoacidity of a Nitrogen‐Rich Fused Ring Heteroaromatic Scaffold

AbstractIt is shown that 4‐methyl‐7‐(4‐nitrophenyl)‐triazolo[3,2‐c]triazole exhibits a high photoacidity, unprecedented in neutral molecules in which the proton is delivered by a NH bond, which promotes acetalization of aldehydes under irradiation by a near‐UV low power LED. Time dependent transient absorption spectroscopy shows a series of stimulated emission signals attributable to photo‐tautomerization and formation of the deprotonated species, followed by broad positive absorption band which does not decay within the investigated timescale, compatible with the formation of a long living species, possibly the anion in the lowest energy triplet state. Computational analyses qualitatively confirm the strong photoacidity of the molecule in all its tautomeric forms, allow to assign transient absorption signals, and show that the first singlet excited state exhibits high spin‐orbit couplings with excited triplet states which could promote a fast singlet‐triplet transition, thus leading to a long living species able to photocatalyze chemical reactions.

Effective Cr(VI) reduction over high throughput Bi-BDC MOF photocatalyst

High throughput Bi-BDC metal-organic framework (BDC = benzene-1,4-dicarboxylic acid) with uniform rod-like morphology was prepared by microwave-assisted method, which could accomplish completely photocatalytic Cr(VI) reduction within 6.0 min under low-power LED UV light with the presence of tartaric acid (TA). The Cr(VI) reduction performance of as-prepared Bi-BDC photocatalyst was slightly influenced by the environmental factors including pH and different inorganic ions. The as-obtained Bi-BDC MOF could be used for five runs’ operation with constant photocatalysis performance. As well, the Cr(VI) reduction mechanism with the presence of TA over the Bi-BDC photocatalyst was clarified.

NIRSCam: A Mobile Near-Infrared Sensing System for Food Calorie Estimation

The calculation of calorie consumption is of paramount importance for the human diet and health management. Most existing solutions use image-processing techniques to identify the food type and refer to the nutrition table to compute the total calorie, which is quite challenging to differentiate foods that look the same but contain vastly different quantities of calories. To address this issue, we propose to leverage near-infrared spectroscopy (NIRS) to derive the concentration of nutrients based on the unique absorption spectrum of foods. Instead of using the professional NIRS system that is bulky, expensive, and impractical for daily use by nonexpert users, we develop a low-cost portable NIRS system using commercial LEDs. As the quality of the signals of the low-power LEDs is relatively poor, we carefully design modulation schemes and interference elimination algorithms to improve the signal quality and remove the interference. Extensive experiments show that NIRSCAM outperforms the image-based baseline in achieving more accurate calorie estimation, especially for look-alike foods and is robust to various environmental factors.

Light-Activated CO Donor as a Universal CO Surrogate for Pd-Catalyzed and Light-Mediated Carbonylation.

A low-molecular-weight, solid CO surrogate that only requires a low-power LED for activation to release 2 equiv of CO is reported. The surrogate can be universally implemented in various palladium-catalyzed carbonylative transformations. It is also compatible with protocols that employ blue-light to activate conventionally inaccessible substrates such as nonactivated alkyl halides. Furthermore, we demonstrate that the photolabile CO-releasing scaffold can be installed into polymeric materials, thereby creating new materials with CO-releasing capabilities.