Natural Sunlight Illumination Research Articles

Highly efficient photocatalysis-Fenton degradation of antibiotics and phenol over sulfidated FeOCl under natural sunlight illumination

Sulfidated FeOCl is prepared as a heterogeneous photo-Fenton catalyst. And the surface sulfidation of FeOCl can remarkably accelerate the photoinduced charge separation and transfer, while also increase Fe2+/Fe3+ atomic ratio, leading to the boosted photo-Fenton activity in the presence of H2O2. Under irradiation of natural sunlight (light intensity: ∼80 mW·cm−2), over 10 mg sulfidated FeOCl catalyst with using 20 μL 15 % H2O2, 91.2 % of ofloxacin solution (50 mg·L−1) and 97.5 % of sulfisoxazole solution (60 mg·L−1) can be degraded in 80 min, and 99.6 % of phenol solution (625 mg·L−1) is decomposed in 4 h. Under irradiation of a white Light-Emitting Diode (LED) lamp (light intensity: 5 mW·cm−2), 99.8 % of ofloxacin solution is decomposed after treatment for 4 h. Moreover, this photo-Fenton degradation system displays a stable activity in a wide range of pH (1−10), diverse water bodies, and various coexisting ions with concertation from 1 mM to 500 mM. Moreover, sulfidated FeOCl catalyst coated on a frosted glass sheet exhibits excellent stability for degrading ofloxacin even in seven continuous cycles. Particularly, the non-toxicity of the treated ofloxacin, sulfisoxazole, and phenol solution, have been proven by testing their toxic effects on cabbage seed, bacteria, and human embryonic kidney cell, respectively.

Oxygen-deficient AgIO3 for efficiently photodegrading organic contaminants under natural sunlight

Defect engineering is regarded as an effective strategy to boost the photo-activity of photocatalysts for organic contaminants removal. In this work, abundant surface oxygen vacancies (Ov) are created on AgIO3 microsheets (AgIO3-OV) by a facile and controllable hydrogen chemical reduction approach. The introduction of surface Ov on AgIO3 broadens the photo-absorption region from ultraviolet to visible light, accelerates the photoinduced charges separation and migration, and also activates the formation of superoxide radicals (•O2−). The AgIO3-OV possesses an outstanding degradation rate constant of 0.035 min−1, for photocatalytic degrading methyl orange (MO) under illumination of natural sunlight with a light intensity is 50 mW/cm2, which is 7 and 3.5 times that of the pristine AgIO3 and C–AgIO3 (AgIO3 is calcined in air without generating Ov). In addition, the AgIO3-OV also exhibit considerable photoactivity for degrading other diverse organic contaminants, including azo dye (rhodamine B (RhB)), antibiotics (sulflsoxazole (SOX), norfloxacin (NOR), chlortetracycline hydrochloride (CTC), tetracycline hydrochloride (TC) and ofloxacin (OFX)), and even the mixture of organic contaminants (MO-RhB and CTC-OFX). After natural sunlight illumination for 50 min, 41.4% of total organic carbon (TOC) for MO-RhB mixed solution can be decreased over AgIO3-OV. In a broad range of solution pH from 3 to 11 or diverse water bodies of MO solution, AgIO3-OV exhibits attractive activity for decomposing MO. The MO photo-degradation process and mechanism over AgIO3-OV under natural sunlight irradiation has been systemically investigated and proposed. The toxicities of MO and its degradation intermediates over AgIO3-OV are compared using Toxicity Estimation Software (T.E.S.T.). Moreover, the non-toxicity of both AgIO3-OV catalyst and treated antibiotic solution (CTC-OFX mixture) are confirmed by E. coli DH5a cultivation test, supporting the feasibility of AgIO3-OV catalyst to treat organic contaminants in real water under natural sunlight illumination.

Sunlight-activated Mo-doped La2CuO4/rGO perovskite oxide nanocomposite for photocatalytic treatment of diverse dyes pollutant

The pristine La2CuO4, Mo-doped, and rGO-supported nanocomposites were fabricated by a simple Pechini route. FTIR and XRD analysis confirmed the fabrication of the perovskite structure. The XRD results exhibit that the prepared products have no impurities and the dopant element is successfully incorporated into the perovskite material. FESEM images exhibit the morphology of synthesized perovskite material. EDX data showed the existence of lanthanum, copper, molybdenum, carbon, and oxygen in grown material. The energy band gap of the rGO-based composite was narrow compared with other samples. The photodegradation capability of the rGO-base catalyst was achieved 99.4 % (MB), 98.8 % (MO), 99.35 % (MR), 98.7 % (RhB), and 99.6 % (SO) in 75 min under natural sunlight illumination. The scavenger experiment revealed that superoxide and hydroxyl radicals are active species during the decolorization reaction. Moreover, this catalyst is stable for six cycles. The synthesized perovskite is an effective material for water purification and environmental remediation.

Phase Change Material Boosting Electricity Output and Freshwater Production through Hierarchical‐Structured 3D Solar Evaporator

AbstractIntermittent sunlight irradiation severely limits the performance of solar evaporators for electricity output and freshwater production. To address this issue, a hierarchical‐structured three‐dimentional (3D) solar evaporator to simultaneously enhance output voltage and freshwater production by integrating a paraffin‐type phase change material (PCM) with a circular concave‐shaped 3D supporter covered with a carbon‐black‐nanoparticles‐modified poly(ethylene terephthalate) fabric (PMCB) is developed. In this developed 3D solar evaporator, the 3D‐printed supporter can trap sunlight to improve solar energy absorption, and the PMCB obtained from hydrophilic and hydrophobic modification can adequately absorb sunlight for electricity generation and water evaporation, resulting in a maximum output voltage of 3.51 V and a high evaporation rate of 4.0 kg m−2 h−1 under natural sunlight illumination. Owing to the introduction of the PCM, the 3D solar evaporator obtains a decrease in the time required for charging a capacitor by 57.9% and an increase in freshwater production by 29.9% compared to the counterpart without a PCM. Through rationally utilizing the solar photothermal energy stored by the PCM and innovatively integrating the PCM and PMCB in a hierarchical‐structured 3D supporter, the developed 3D solar evaporator exhibits great application potential for simultaneous electricity generation and freshwater supply under intermittent solar irradiation.

Enhanced photocatalytic degradation of organic pollutants in water using copper oxide (CuO) nanosheets for environmental application

Rapid, inexpensive, and low-power/solar light-driven photocatalytic degradation of organic pollutants to deal with annually produced trillion tons of synthetic dye wastewater to prevent water scarcity issues, ecotoxicological risks, and human health has always been challenging. To overcome this limitation, the present study synthesized earth-abundant, inexpensive copper oxide nanosheets using a simple single-step hydrothermal route. The structural, physicochemical, and functional properties of the nanosheets have been characterized using several characterization techniques. The photocatalytic activity was studied for two commonly industrially used organic dyes, Methylene Blue (MB) and Rhodamine B (RhB). The importance of this work is the usage of a cheap commercially available Phillips UV light (11 W) as well as direct sunlight. With several optimized conditions, almost complete degradation of both dyes was achieved within 35 minutes under low-power UV light and within 70 minutes by the direct illumination of natural sunlight. The enhanced photocatalytic performance can be correlated to the synergetic effect of a higher charge transfer mechanism, good catalytic ‘active surface area’ availability (13.2 m2/g), and several optimized parameters that affect the reaction efficacy. Additionally, five repeated uses of nanosheets without sacrificing performance confirmed their stability and sustainability as a promising candidate for large-scale industrial textile wastewater remedies.

Sunlight assisted degradation of methylene blue dye by zinc oxide nanoparticles green synthesized using Vitex negundo plant leaf extract

Zinc oxide nanoparticles (ZnO NPs) were formed through a simple green synthesis route using Vitex negundo (V. negundo) leaf extract as reducing and capping source. Morphological, structural, chemical and optical features of the prepared ZnO NPs were examined by field emission SEM, XRD, EDAX, PL, FTIR and UV–vis DRS, respectively. FESEM images precisely visualized morphology of the ZnO NPs as spherical with particles size ranges between 5 and 35 nm having a mean diameter of ∼ 19 nm. XRD pattern revealed formation of hexagonal wurtzite structured ZnO NPs with high crystallinity. Further, the observed asymmetric stretching vibration of Zn-O bond confirmed the formation of hexagonal wurtzite structured ZnO NPs. Photocatalytic activity of the ZnO NPs was assessed against methylene blue (MB) dye degradation under natural sunlight illumination. Results of the photocatalytic experiment disclosed an impressive MB dye degradation efficiency of 98.50 % at 60 min. Moreover, green synthesized ZnO NPs exhibited a maximum mineralization (TOC removal) efficiency of 92.34 % at 5 h of sunlight illumination.

Comparative study of the photogalvanics of Sudan-I, Rhodamine-B, Fast Green FCF, Brilliant Cresyl Blue, Naphthol Green B, and chlorophyll ‘a’ photosensitizers at natural sunlight illumination intensity

Photogalvanic cells provide a route for simultaneous solar power and storage. The synthetic and natural photosensitizers having absorption in different spectral regions have been studied at natural sun intensity for simultaneous solar power and storage. The dye sensitizers [Sudan-I (SUD); Rhodamine-B (RHD); Fast Green FCF (FCF); Brilliant Cresyl Blue (BCB); Naphthol Green B (NGB)], and chlorophylls present in aqueous crude spinach extract (SPE) have been used. The observed power and efficiency for various sensitizers are respectively as- 610.8 μW, 7.63% for SUD; 620.1 μW, 7.75% for RHD; 654 μW, 8.17% for SPE; 661 μW, 8.26% for BCB; 649.6 μW, 8.12% for FCF; 625.8 μW, 7.82% for NGB; 596.2 μW, 7.45% for mixed NGB+FCF+BCB; 595.4 μW, CE 7.44% for mixed NGB + FCF + BCB + SPE; 587.6 μW, 7.34% for mixed NGB + FCF +BCB + SPE + RHD; and 639.6 μW, 7.99% for mixed NGB + FCF +BCB + SPE + RHD + SUD. The photogalvanic cell performance as the current, potential, and power for various photo sensitizer(s) is practically same at natural sun intensity as well. The power storage capacity of the various photosensitizer (s) may be different.

Integration of WO3-Doped MoO3 with ZnO Photocatalyst for the Removal of 2-Nitrophenol in Natural Sunlight Illumination

Environmental contamination has become the most pressing issue in recent years. The value of clean water to mankind has sparked interest in heterogeneous photocatalysis. In this study, a novel photocatalyst has been synthesized by integrating WO3-doped MoO3 (WDM) and ZnO through composite formation. The composite nature of the synthesized photocatalyst was confirmed due to the presence of hexagonal ZnO and orthorhombic WDM phases in XRD pattern and scanning electron micrographs. Solid-state absorption spectra and a bandgap analysis showed that WDM-spectral ZnO’s response was better than that of pure ZnO. PL and EIS unveiled the effective role of WDM in suppressing the e−–h+ recombination process and charge-transfer resistance, respectively, in ZnO. The photocatalytic studies showed that WDM-ZnO was able to remove ~90% of 30 ppm 2-nitrophenol (2-NP) with a rate of 1.1 × 10−2 min−1, whereas ~65% 2-NP was removed by ZnO (6.1 × 10−3 min−1 rate) under the exposure of natural sunlight (800 × 102 ± 100 lx). Moreover, ~52% higher total organic carbon (TOC) removal was observed by WDM-ZnO as compared to ZnO. The photocatalytic removal of 2-NP by the produced photocatalysts followed the Langmuir–Hinshelwood kinetic model, as shown by the kinetic studies. The reactive oxygen species (ROS)-trapping established that the photocatalytic removal mechanism of 2-NP over WDM-ZnO in sunlight illumination was mainly triggered by the superoxide anion (O2•−) radical, however, the minor role of hydroxyl (•OH) radicals cannot be completely ignored.

The Impact of Different Green Synthetic Routes on the Photocatalytic Potential of FeSnO2 for the Removal of Methylene Blue and Crystal Violet Dyes under Natural Sunlight Exposure

FeSnO2 nanocomposites were synthesized via the green method using aqueous leaf extracts of Lawsonia inermis and Phyllanthus embilica plants. The role of polyphenols based on reduction potentials for the synthesis of FeSnO2 was also highlighted. The synthesized materials were examined by using TGA and DSC, FT-IR, XRD, and SEM with EDX analysis. Tetragonal rutile and distorted hexagonal structures were observed in SEM images of the FeSnO2 nanocomposites and compared with an FeSnO2 nanocomposite prepared using the sol-gel method. Scherer’s formula yielded crystallite sizes of 29.49, 14.54, and 20.43 nm; however, the average crystallite size assessed employing the Williamson–Hall equation was found to be 20.85, 11.30, and 14.86 nm by using the sol-gel and green techniques, using extracts from Lawsonia inermis and Phyllanthus embilica. The band gap was determined by using the Tauc and Wood equations, and photocatalytic activity was analyzed to determine the degradation of methylene blue (MB) and crystal violet (CV) under the illumination of natural sunlight. It was observed that the sample prepared by means of the green method using the leaf extract of Lawsonia inermis showed the best photocatalytic activity of 84%, with a particle size of 14.54 nm, a 3.10 eV band gap, and a specific surface area of 55.68 m2g−1.

Rational Design of Monolithic g-C3N4 with Floating Network Porous-like Sponge Monolithic Structure for Boosting Photocatalytic Degradation of Tetracycline under Simulated and Natural Sunlight Illumination.

In order to solve the problems of powder g-C3N4 catalysts being difficult to recycle and prone to secondary pollution, floating network porous-like sponge monolithic structure g-C3N4 (FSCN) was prepared with a one-step thermal condensation method using melamine sponge, urea, and melamine as raw materials. The phase composition, morphology, size, and chemical elements of the FSCN were studied using XRD, SEM, XPS, and UV-visible spectrophotometry. Under simulated sunlight, the removal rate for 40 mg·L-1 tetracycline (TC) by FSCN reached 76%, which was 1.2 times that of powder g-C3N4. Under natural sunlight illumination, the TC removal rate of FSCN was 70.4%, which was only 5.6% lower than that of a xenon lamp. In addition, after three repeated uses, the removal rates of the FSCN and powder g-C3N4 samples decreased by 1.7% and 2.9%, respectively, indicating that FSCN had better stability and reusability. The excellent photocatalytic activity of FSCN benefits from its three-dimensional-network sponge-like structure and outstanding light absorption properties. Finally, a possible degradation mechanism for the FSCN photocatalyst was proposed. This photocatalyst can be used as a floating catalyst for the treatment of antibiotics and other types of water pollution, providing ideas for the photocatalytic degradation of pollutants in practical applications.

Direct Z-scheme In2O3/AgI heterojunction with oxygen vacancies for efficient molecular oxygen activation and enhanced photocatalytic degradation of tetracycline

A novel In2O3/AgI heterojunction, which has a hollow tubular structure with AgI particles distributed evenly on the outer and inner surfaces of In2O3 microtubes, was fabricated from annealing of AgI adhered to MIL-68(In). The as-prepared heterojunction exhibited much higher photocatalytic activity towards tetracycline degradation compared to In2O3 and AgI. The presence of InAg-1 (1.0 g/L), which has a In2O3:AgI mole ratio of 2:1, could achieve 98.4% removal of tetracycline (20 mg/L) from the solution phase under visible light illumination in 10 min, and it had excellent reusability and stability. The In2O3/AgI heterojunction also exhibited excellent performance in photocatalytic degradation of tetracycline in different types of water matrices and under natural sunlight illumination, demonstrating its potential in practical application. The superior photocatalytic activity of InAg-1 is attributed to the heterojunction formation and generation of oxygen vacancies (OVs), which improve the separation efficiency of photoinduced e−-h+ pairs. Meanwhile, the built-in electric field (BIEF) formed with e- flowing from AgI to In2O3, which is confirmed by density functional theory calculations, helps the formation of a Z-scheme, instead of type II, heterojunction between In2O3 and AgI. Results of radical trapping experiments and electron spin resonance spectra reveal that 1O2, h+, •O2−, and •OH were the key reactive species involved in the photocatalytic degradation process. These findings indicate that Z-scheme photocatalysts with OVs could efficiently activate molecular oxygen and thus have excellent photocatalytic activity towards degradation of organic pollutants.

Comprehensive analysis of solar cell behavior: effects of light intensity, temperature, and operational modes

This study investigates the current-voltage characteristics of a solar cell under varying light intensities, temperatures, and operational conditions to comprehensively assess its performance. The experimental approach involves measuring short-circuit current and open-circuit voltage at different light intensities and constructing current-voltage curves to analyze the solar cell's response to changing illumination levels. The dependence of open-circuit voltage and short-circuit current on temperature is also estimated to understand thermal influences on the solar cell's electrical properties. Additionally, the solar cell's behavior is examined under different operational modes, including cooling with a blower, operation without cooling, and light filtration through a glass plate. The corresponding current-voltage characteristics are plotted to evaluate the impact of thermal management and light modulation on the solar cell's efficiency and stability. Furthermore, the characteristic curve of the solar cell is determined under natural sunlight illumination to simulate real-world conditions. The findings provide valuable insights into optimizing solar cell performance for practical applications and sustainable energy systems. This research contributes to advancing our understanding of solar cell behavior under diverse environmental and operational settings, with implications for enhancing solar energy utilization and promoting renewable energy technologies. Future studies will focus on refining solar cell design and operation based on these insights to maximize efficiency and reliability in solar power generation.

Biogenic Preparation of ZnO Nanostructures Using Leafy Spinach Extract for High-Performance Photodegradation of Methylene Blue under the Illumination of Natural Sunlight.

To cope with environmental pollution caused by toxic emissions into water streams, high-performance photocatalysts based on ZnO semiconductor materials are urgently needed. In this study, ZnO nanostructures are synthesized using leafy spinach extract using a biogenic approach. By using phytochemicals contained in spinach, ZnO nanorods are transformed into large clusters assembled with nanosheets with visible porous structures. Through X-ray diffraction, it has been demonstrated that leafy spinach extract prepared with ZnO is hexagonal in structure. Surface properties of ZnO were altered by using 10 mL, 20 mL, 30 mL, and 40 mL quantities of leafy spinach extract. The size of ZnO crystallites is typically 14 nanometers. In the presence of sunlight, ZnO nanostructures mineralized methylene blue. Studies investigated photocatalyst doses, dye concentrations, pH effects on dye solutions, and scavengers. The ZnO nanostructures prepared with 40 mL of leafy spinach extract outperformed the degradation efficiency of 99.9% for the MB since hydroxyl radicals were primarily responsible for degradation. During degradation, first-order kinetics were observed. Leafy spinach extract could be used to develop novel photocatalysts for the production of solar hydrogen and environmental hydrogen.

Adsorption Efficiency and Photocatalytic Activity of Silver Sulfide Nanoparticles Deposited on Carbon Nanotubes

A multimode, dual functional nanomaterial, CNTs-Ag2S, comprised of carbon nanotubes (CNTs) and silver sulfide (Ag2S) nanoparticles, was prepared through the facile hydrothermal process. Before the deposition of Ag2S nanoparticles, hydrophobic CNTs were modified to become hydrophilic through refluxing with a mixture of concentrated nitric and sulfuric acids. The oxidized CNTs were employed to deposit the Ag2S nanoparticles for their efficient immobilization and homogenous distribution. The CNTs-Ag2S could adsorb toxic Cd(II) and completely degrade the hazardous Alizarin yellow R present in water. The adsorption efficiency of CNTs-Ag2S was evaluated by estimating the Cd(II) adsorption at different concentrations and contact times. The CNTs-Ag2S could adsorb Cd(II) entirely within 80 min of the contact time, while CNTs and Ag2S could not pursue it. The Cd(II) adsorption followed the pseudo-second-order, and chemisorption was the rate-determining step in the adsorption process. The Weber−Morris intraparticle pore diffusion model revealed that intraparticle diffusion was not the sole rate-controlling step in the Cd(II) adsorption. Instead, it was contributed by the boundary layer effect. In addition, CNTs-Ag2S could completely degrade alizarin yellow R in water under the illumination of natural sunlight. The Langmuir-Hinshelwood (L-H) model showed that the degradation of alizarin yellow R proceeded with pseudo-first-order kinetics. Overall, CNTs-Ag2S performed as an efficient adsorbent and a competent photocatalyst.

Boosted natural sunlight driven photodegradation of organic dyes using rGO anchored Pr/Cu dual-doped ZnO nanocomposite: Characterization and mechanistic insight

The advancement of sunlight-driven metal oxide semiconductor-based, highly efficient photocatalysts for removing contaminants like dyes from wastewater remained a challenge. In this work, Pr/Cu dual-doped ZnO anchored with different rGO concentrations were synthesized by simple co-precipitation and ultrasonication route. The structural, morphological, and optical characterization of prepared materials was performed with different techniques and employed for degrading diverse kinds of dyes pollutants under natural sunlight illumination. The photodegradation efficiency after 40 min sunlight illumination towards Methyl Orange (MO) was 51.00, 75.00, and 99.76% for ZnPrCuO (S1), ZnPrCuO/rGO (1:1) (S2), and ZnPrCuO/rGO (1:2) (S3), respectively. The results suggested that the introduction of Pr/Cu and rGO significantly boosted the photodegradation ability of ZnO under sunlight. Especially, S3 nanocomposite exhibited the highest photodegradation of safranin-O (SO), Rhodamine-B (RhB), and methylene blue (MB) dyes, having degradation efficiency of 65.50, 91.40, and 99.80%, respectively, in 40 min. The scavenger test results exhibited that •OH and •O2− were the foremost active species in the photodegradation process. Moreover, the reusability experiments and tracing XRD after reusing samples revealed that the S1 catalyst has excellent recyclability (6th cycle). The reduction in energy bandgap and creation of impurity energy level by Pr/Cu doping leads to inhibit carrier pair recombination and effective charge transfer/separation. These findings revealed that Pr/Cu doping and rGO have the potential to enhance the visible light response of ZnO to eliminate dyes pollutants in wastewater with energy saving.

Silver Sulfide Nanocrystals as a Biocompatible and Full-Spectrum Photocatalyst for Efficient Light-Driven Polymerization under Aqueous and Ambient Conditions

Owing to current global environmental concerns, polymers must be prepared under eco-friendly reaction conditions based on sustainable chemistry. In this context, highly efficient photoinduced energy/electron transfer reversible addition–fragmentation chain-transfer (PET-RAFT) polymerization under ambient/aqueous conditions without additives and/or with the aid of sunlight is the optimal approach for producing polymers with well-defined structures. This can be accomplished with a photocatalyst (PC) that utilizes the full spectrum of sunlight for maximum efficiency and has excellent water solubility or dispersibility, oxygen tolerance, and biocompatibility. However, a PC with all of these features has not yet been developed. In this study, we confirmed that this could be achieved using Ag2S nanocrystals (NCs) as photocatalysts. The sufficient reducing power of Ag2S NCs enabled the successful aqueous PET-RAFT polymerization of numerous acrylic monomers under ambient natural sunlight illumination without any additives. Under illumination, the small band gap of Ag2S NCs suppressed the generation of singlet oxygen, resulting in low cytotoxicity toward three different cell lines. Finally, we demonstrated that PET-RAFT polymerization with Ag2S NCs can be accomplished in biologically relevant media under natural sunlight illumination, indicating adequate biocompatibility and efficacy of the system.

Construction of BiOIO3/AgIO3 Z-Scheme Photocatalysts for the Efficient Removal of Persistent Organic Pollutants under Natural Sunlight Illumination.

The efficient removal of persistent organic pollutants (POPs) in natural waters is vital for human survival and sustainable development. Photocatalytic degradation is a feasible and cost-effective strategy to completely disintegrate POPs at room temperature. Herein, we develop a series of direct Z-scheme BiOIO3/AgIO3 hybrid photocatalysts via a facile deposition-precipitation method. Under natural sunlight irradiation, the light intensity of which is ∼40 mW/cm2, a considerable rate constant of 0.185 min-1 for photodecomposing 40 mg/L MO is obtained over 0.5 g/L Bi@Ag-5 composite photocatalyst powder, about 92.5 and 5.3 times higher than those of pristine AgIO3 and BiOIO3. The photoactivity of Bi@Ag-5 for photodecomposing MO under natural sunlight illumination surpasses most of the reported photocatalysts under Xe lamp illumination. After natural sunlight irradiation for 20 min, 95% of MO, 82% of phenol, 78% of 2,4-DCP, 54% of ofloxacin, and 88% of tetracycline hydrochloride can be photodecomposed over Bi@Ag-5. Relative to the commercial photocatalyst TiO2 (P25), Bi@Ag-5 exhibits greatly higher photoactivity for the treatment of MO-phenol-tetracycline hydrochloride mixture pollutants in the scale-up experiment of 500 mL of solution, decreasing COD, TOC, and chromaticity value by 52, 19, and 76%, respectively, after natural sunlight irradiation for 40 min. The photodegradation process and mechanism of MO have been systematically investigated and proposed. This work provides an archetype for designing efficient photocatalysts to remove POPs.

Engineering of ZnO/Graphene Nanocomposite for Enhancing Visible Photocatalytic Ability

Herein, the visible light‐photocatalytic performance of synthesized ZnO/Gr composite materials with different Gr content under various conditions, i.e., pH, dye concentration, and different scavengers (to understand the photocatalytic activity mechanism) is systematically investigated. Photocatalytic performance is evaluated with the degradation of methylene blue (MB) in solution under sunlight irradiation. The presence of graphene (Gr) in the ZnO/Gr composites shows enhanced photocatalytic activity compared to pure ZnO under natural sunlight illumination. The highest photodegradation efficiency of ≈94% when the content of Gr is 1 wt% in comparison to ≈76% for the pure ZnO, corresponding to reaction rate constants of 0.01038 and 0.00615 min−1, respectively. Compared to recent publications, the degradation efficiency is high with relatively high dye concentration, low catalyst amount, and large solution volume. The enhanced visible light absorption and the reduction of bandgap value are attributed to the enhanced photocatalytic properties of the hybridized composite. Moreover, the investigation of the effect of scavenger substances shows that H2O2 strongly enhanced their photocatalytic ability, suggesting that holes (h+) contribute as the reactive agent in the photodegradation process.

Natural-sunlight-driven synchronous degradation of 4-nitrphenol and rhodamine B over S-scheme heterojunction of α-Fe2O3 nanoparticles decorated CuBi2O4 rods

Enhancing photocatalytic efficiency of mixed-pollutant degradation is a critical issue for the application in wastewater purification, especially under natural-sunlight illumination. CuBi2O4 rods decorated with Fe2O3 nanoparticles were synthesized by the hydrothermal method. The Fe2O3/CuBi2O4 composites exhibited significantly enhanced photocatalytic activity for Fenton oxidation of Rhodamine B (RhB) and 4-nitrophenol (4-NP) in the near-neutral catalytic system, and the degradation efficiency of the above two pollutants reached above 90% after 50 min of visible-light irradiation. Meanwhile, the good catalytic performance and stability were maintained in the seventh cycling test. Notably, the efficient synchronous degradation of the above mixed pollutants was accomplished under natural-sunlight over the optimal 7%Fe2O3/CuBi2O4 catalyst. The staggered band structure in the heterojunction was determined by DRS and UPS results, and the S-scheme electron transfer mode was verified by the in situ-XPS measurement under dark and light conditions. The study is expected to be beneficial to explore step-scheme (S-scheme) semiconductor photocatalysts for natural-sunlight-driven Fenton oxidation of mixed pollutants.

Green synthesis of ZnO nanoparticles using Acalypha indica leaf extract and their photocatalyst degradation and antibacterial activity

The aim of the current study was to synthesize nanoparticles of Zinc oxide (ZnO) using extract of Acalypha indica leaves and their photocatalyst degradation and antibacterial properties were also measured. The biosynthesized nanoparticles were analysed using XRD, UV–visible, FT-IR, SEM with EDAX, DLS, PL and Zeta potential analysis. The synthesized nanoparticles had a mean size of 16 nm measured by XRD which was highly pure, and their spherical shape was confirmed by SEM. UV–Visible confirmed that ZnO nanoparticles have a direct band gap energy at 3.34 eV. The measured zeta size and potential of synthesized nanoparticles were 46 nm and −27 mV, respectively, determined by the DLS technique can be considered moderately stable colloidal solution. The FT-IR analysis confirmed the presence of functional groups in the leaf extract and the ZnO nanoparticles. The PL analyses performed on ZnO nanoparticles showed a sharp blue band at 362 nm, which was attributed to the defects of structure in ZnO crystals. During natural sunlight illumination, ZnO nanoparticles demonstrated notable degradation of the dye methyl blue (MB). At 90 min of illumination, the degradation efficiency achieved was 96%. Antibacterial properties were observed for synthesized ZnO nanoparticles against four bacterial strains, including Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The highest zone of inhibition was observed against Escherichia coli (25.2 mm). Overall, these studies indicate that Acalypha indica is a good sell for planting, and has the greatest chance of being used to develop nanoparticles for protection against environmental pollution and human health.