Simulated Solar Irradiation Research Articles

Decorated ZnO nanorods with Bi2S3 nanosheets for enhanced photocatalytic removal of antibiotics and analgesics: Degradation mechanism and pathway

Novel nanorods (NRs) of Bi2S3-ZnO (BZ) heterojunction have been prepared using a microwave-assisted hydrothermal approach. The photocatalytic behavior of BZ heterojunction NRs has been investigated under simulated solar irradiation against the mineralization of meloxicam (MX) analgesics, sulfamethoxazole (SMX), trimethoprim (TMP) antibiotics, as well as crystal violet (CV) and malachite green (MG) dyes. XRD, FTIR, SEM, EDX, TEM, UV–Vis, BET, Zeta potential, and Pl techniques are used to characterize the prepared samples. The TEM results showed that the ZnO NRs are wrapped with Bi2S3 NSHs. For SMX and MX, the degradation rate of BZPCis 2.46 and 1.6 fold greater than that for pristine ZnO NRs, respectively. Furthermore, the BZ NRs heterojunction demonstrated 100% degradation efficiency for SMX, SM, TMP, and CV after 120 min, and after 60 min for MG. The enhanced photodegradation activity of BZ NRs photocatalyst (PC) is assigned to its high absorption ability for visible light, increased surface area, adsorption capability, as well as inhibition of the hole-electron recombination process according to the PL study. Furthermore, the quenching experiment exposed that hydroxyl radicals (·OH) exhibit a significant role in the photodegradation process.Moreover, after 5 cycles, the photocatalytic degradation efficiency of the BZ PC remained constant, confirming its high stability and reusability. The special charge transfer pathway over the BZ PC has been investigated, which will assistin the design of systems with superior photocatalytic properties. The degraded productsand pathwaysis also proposed.Conclusively, BZis considered stable, efficient, and non-selective PC for green solar-driven photocatalytic degradation.

The effect of defects induced by polarization on bandgap evolution and photovoltaic performance in KN-based semiconducting ferroelectric ceramics

The high-field polarization enables bandgap-engineered ferroelectric perovskite oxides to further enhance their photovoltaic performance. However, research on the mechanism of the high-field polarization-enhanced ferroelectric photovoltaic effect lacks understanding in terms of bandgap evolution. In this work, the ceramics [KNbO3]1−x−[SrNi0.5Hf0.5O3−δ]x(KNSNH100x, x = 0.02 − 0.08), prepared by the solid phase method, exhibit good ferroelectricity and four absorption bandgaps, three of which have sub-bandgaps generated by Ni. The effect of increased defects induced by high-field polarization on bandgap evolution and photovoltaic properties was investigated. The increase in defect concentration in KNSNH2 induced by high-field polarization is the cause of the variation in bandgap structure in KNSNH2. Structural refinement suggests that the change in the bandgap after polarization can be induced by the lattice distortion. The evolution of bandgap structure after polarization in KNSNH2 lead to an enhancement of visible light absorption, which further improve the photovoltaic performance by produced more carriers. A two-fold enhancement of short-circuit photocurrent density (Jsc) under simulated solar irradiation is achieved in the KNSNH2 sample by polarization. This work provides new insights into the effect of defect induced by polarization on enhancing ferroelectric photovoltaic performance and the mechanism of bandgap evolution.

CoFe2O4/MoS2@Au: Multifunction Z-Scheme Heterojunction for SERS Monitoring and Photocatalytic Degradation of Fungicides

Efficient detection and degradation of fungicides are greatly concerned with aquatic food safety. Herein, a multifunction CoFe2O4/MoS2@Au (ACMS) composite was synthesized for crystal violet (CV) and malachite green (MG) photocatalytic degradation and SERS determination. As the construction of the Z-scheme heterostructure of ACMS, which enhanced the light absorption capability and the separation efficiency of photoexcited carrier significantly, ACMS possessed an excellent photocatalytic performance with a degradation rate of 94.76% for CV under simulated solar light irradiation. Furthermore, the multifunction ACMS exhibited superior SERS capability with a detection limit (LOD) of 4.309 × 10−2 μg L−1 for MG residues in water. And the ACMS substrates could be utilized to determine the MG residues in crucian carp extract, resulting in a recovery rate of 96.00~116.00%. In addition, such multifunction heterojunctions were performed for in situ monitoring of the photodegradation process. This research opened up a novel perspective on the applications of heterojunction-based multifunction materials for food safety control.

Design, Synthesis, and Photophysical Characterization of Multifunctional Far‐Red Squaraine Dyes for Dye‐Sensitized Solar Cells

Novel far‐red sensitive symmetrical squaraine (SQ) dyes aiming toward multifunctional properties such as control of dye aggregation, promotion of molecular self‐assembly, and introduction of electrolyte function by alkyl chain terminal modification are designed. Newly designed dyes without terminal modification as reference (SQ‐5) along with iodine (SQ‐77) and imidazole (SQ‐79) alkyl terminal‐modified dyes are successfully synthesized, characterized, and subjected to detailed photophysical investigations. Iodine terminal modification (SQ‐77) leads to enhanced molar extinction coefficient, dye aggregation, dye loading, and binding strength on the TiO2 surface, which is found by just the opposite after the imidazole (SQ‐79) terminal modification. Demonstration of nearly similar photovoltaic performance by SQ‐77 and SQ‐79 in the absence of iodine and chenodeoxycholic acid validates their multifunctional role as electrolyte function and dye aggregation prevention, respectively, in addition to their main role as photosensitizer. Dye‐sensitized solar cells fabricated with SQ‐5 as a sensitizer show efficient far‐red to near‐infrared photo sensitization and photon harvesting with short‐circuit photocurrent density, open‐circuit voltage, and fill factor of 11.98 mA cm−2, 0.61 V, and 0.57, respectively, leading to a photoconversion efficiency of 4.2% under simulated solar irradiation.

A hybrid study of a 4-stage compressed solar distiller based on experimental, computational and deep learning methods

In the present study, a hybrid technique is employed to demonstrate the thermal performance of a 4-stage compressed solar distiller with hydrophilic evaporators (CSDHE) regarding the role of natural convection in the air gap domain. Initially, the test is conducted under simulated solar radiation of 2.13 W·m−2 over 5400 s. A thermodynamic model incorporating diffusion is developed for the next step to analyze internal transient temperatures. In the third step, a 3D single-phase natural convection model of the CSDHE is simulated to achieve the research objectives. Based on experimental, thermal modeling, and computational results, a dual deep neural network is developed to predict the thermal behavior of the system and the variation of convection heat transfer coefficient for different air gap thicknesses over 10,000 s. The experimental results revealed a distilled water production rate of 3.806 kg·m−2h−1 with a gained output ratio (GOR) of 112 %. Moreover, the findings demonstrate that conduction accounts for 84.23 % of total heat transfer, while convection accounts for 6.36 % during 5400 s. We also found that, by employing a convolutional neural network (CNN) and directly harvesting data from pre-defined contours, the hybrid training dataset for deep forward neural network (DFNN) is trained 28.35 % faster than conventional methods.

A novel magnetic photocatalyst SnO2/SrFe12O19 applied in degradation for Rhodamine B

A novel photocatalyst SnO2/SrFe12O19 (SS) was fabricated by a two-step hydrothermal method, and was characterized by XRD, SEM, EDS, XPS, BET, UV-Vis DRS. The photocatalytic activity was assessed through degrading solution of Rhodamine B (RhB) under simulated solar irradiation. The results showed that composite of wt 5% SrFe12O19 (SS-5) had superior photocatalytic activity, and the degrading ratio could reach 83.8% within 120 min, which was more than the pure phase SnO2. Moreover, specific surface area, cumulative pore volume, and average adsorption pore size of SS-5 slightly enhanced, the light absorption range expanded to the visible light direction, and the band gap energy decreased. Meanwhile, the VSM test showed that the magnetization saturation of SS-5 was 1.42 emu/g, and magnetic separation could be achieved. In the photocatalytic degradation process, RhB was successfully degraded under the effect of superoxide radical (·O2−), and photogenerated hole (h+). Based on these findings, possible photocatalytic mechanism was investigated and explained. The fabricated SnO2/SrFe12O19 could be used as a valuable photocatalyst for the treatment of sewage.

Photochemical Release of Dissolved Organic Nitrogen from Algal Detritus and Sediment Particles in Lake Taihu, China

Solar irradiation in aquatic systems can induce the conversion of substances from the solid to the dissolved phase (photodissolution). Yet, the photochemical release of dissolved organic nitrogen (DON) from internal particles in lakes remains largely unknown. In this study, suspensions of algal detritus and sediment particles from a shallow eutrophic lake were exposed to simulated solar irradiation, and the release and compositional changes of dissolved organic matter were explored by measuring their UV–Visible absorption spectroscopy and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The photochemical release of inorganic nitrogen during the incubations was also investigated. Results showed that light irradiation induced stronger dissolved organic carbon and DON production in the algal detritus suspensions, with release rates of 1.17 mg C L−1 h−1 and 0.14 mg N L−1 h−1, respectively, at an algal detritus concentration of 0.1 dry g L−1. Light irradiation also induced compositional changes of DON in both algal and sediment suspensions. A larger number of DON molecules with lower molecular weight were continuously released in the algal suspensions, e.g., the total number of DON formulas increased from 1349 to 4135 during an 8 h irradiation. In contrast, upon irradiation of sediment suspensions, DON showed decreased molecular diversity and increased aromaticity. The photochemical release of ammonium (photoammonification) was also higher in the algal suspensions with a rate of 0.015 mg N L−1 h−1, which may contribute to the eutrophication of the lake. This study provides new molecular insights into the photochemical release of DON from typical internal particles in eutrophic lakes.

Photocatalytic degradation of alkyl imidazole ionic liquids by TiO2 nanospheres under simulated solar irradiation: Transformation behavior, DFT calculations and promoting effects of alkali and alkaline earth metal ions

In this study, TiO2 nanospheres prepared by the sol-gel method were found to efficiently catalyze the photodegradation of 1-butyl-2,3-dimethylimidazolium bromide salt ([BMMIm]Br) under simulated solar irradiation through the main attack of hydroxyl radicals (•OH). The promoting effect of alkali metal (Li+→Cs+) and alkaline earth metal ions (Mg2+→Ba2+) was particularly emphasized. In-situ EPR tests showed that the introduction of alkali and alkaline earth metal ions could enhance the formation of •OH thus leading to a 7%−30.3% increase in the degradation efficiency of. [BMMIm]+. Moreover, the removal efficiency of [BMMIm]+ still reached > 96.19% in four real waters. A total of 23 products of [BMMIm]Br were detected, and hydroxyl substitution, bond breaking, direct oxidation and ring opening were considered as the main reactions during the photocatalytic degradation process. The results of toxicity evaluation showed that hydroxylation was a reaction process of increasing toxicity, while the bond breaking reaction had great detoxification capacity for [BMMIm]+. These findings may enhance our understanding on the effects of alkali or alkaline earth metal ions on the photocatalytic activity of TiO2, which could also provide reference for the efficient and green removal of alkylimidazolium ionic liquids in waters.

Testing carbon structures for metal-free catalytic/photocatalytic ozonation to remove disinfection by-product formation potential

Different graphitic carbon structures were prepared and tested for catalytic and photocatalytic ozonation of the precursors of chlorination disinfection by-products to remove their disinfection formation potential (DBPFP). Commercial graphite was submitted to ball milling and two chemical treatments with ammonium nitrate or potassium oxalate to increase its surface area. Additionally, ozonation in gas phase and liquid phase were used to generate surface oxygen groups in these materials and in commercial graphene. All the carbon samples were tested and compared with commercial graphene oxide in the removal of humic acid solutions. The highest catalytic activity during the catalytic/photocatalytic ozonation of humic acid was observed for commercial graphene, ozonated graphene and for graphene oxide; however, this did not result in high DBPFP removal and the instability of the materials was demonstrated. With a moderate catalytic activity but better stability, ball-milled graphite ozonated in liquid phase, was selected for photocatalytic ozonation of real surface water leading to a high DBPFP removal at the conditions tested (88 % 5-HAAs (haloacetic acids), 70 % 4-THMs (trihalomethanes), 70 % AOX (adsorbable organic halides); conditions: semi-batch experiments; 0.5 L volume; 5 mg L−1 O3; Qg = 10 L h−1; DOC0 = 5 mg L−1; pH = 7.8; 180 min under simulated solar radiation with average irradiance 580 W m−2).

Development of a new composite LDH/TiO2-3D for degradation of sulfaguanidine under UV and visible light: Experimental design, kinetic and mechanisms

Constructing 3D heterostructures has been considered an effective approach to enhance the photocatalytic activity of materials. However, the preparation of 3D heterostructures is always a complex process. In this paper, three-dimensional (3D) spherical TiO2 immobilized on Cu3AlCO3 Layered Double Hydroxides (LDH) was successfully synthesized using the impregnation method. The structure, morphology, and property of Cu3AlCO3-LDH/xTiO2-3D were investigated by X-ray diffraction (XRD), FTIR spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), UV-Visible diffuse reflectance spectroscopy. The photocatalytic properties of composite materials were evaluated by degradation of sulfaguanidine (SGD) antibiotic under simulated solar irradiation. To optimize the photocatalysis process, an experimental design methodology was used. The experimental design utilized in most published works involves simple matrices that focus on quantitative factors. In contrast, our work enables the study of both qualitative factors (dissolved oxygen concentration) and quantitative factors (pH, catalyst dose and temperature) for both responses using a mixed matrix (D‐optimal) and a multiplicative model. To achieve this, 22 Run of experiments designed by the AZURAD® software. The optimal values of pH, catalyst dose, temperature, and dissolved oxygen concentration were found to be 8, 0.23 g.L−1, 25 °C, and 2 mg.L−1, respectively. The transformation product and possible degradation pathways of SGD were identified through Orbitrap LC/MS. Additionally, the present composite photocatalysts exhibited satisfactory re-usability for at least four cycles. Due to the facile synthesis process, higher photocatalytic activity under visible light irradiation and satisfactory re-usability, these composites can be considered as potential catalysts for degrading pharmaceutical pollutants in wastewater treatment.

Modelling and optimisation of MXene-derived TiO2/Ti3C2 synthesis parameters using Response Surface Methodology based on the Box–Behnken factorial design. Enhanced carbamazepine degradation by the Cu-modified TiO2/Ti3C2 photocatalyst

In the present study, a hydrothermal method in a water/ethanol environment was used for the first time to obtain novel Cu/TiO2/Ti3C2 composites with high photocatalytic activity for the degradation of carbamazepine (CBZ) under simulated solar light. The Box–Behnken factorial design was coupled with Response Surface Methodology (RSM) for synthesis parameter optimisation. The effect of different synthesis parameters, including temperature, time and water/ethanol ratio, was for the first time studied in detail. The analysis of variance (ANOVA) was used to verify the adequacy of the proposed model. The water/ethanol ratio was the most influential parameter for anatase crystallite growth and the efficiency of carbamazepine degradation. The TiO2/Ti3C2 sample prepared under the optimised conditions (synthesis time of 17 h, temperature of 220 °C, and water/ethanol ratio of 58:42 v/v) revealed almost 100% of CBZ degradation within 60 min. Furthermore, the surface modification of this sample with 0.25% - 1 wt% of copper resulted in improved photocatalytic activity. For TiO2/Ti3C2 modified with 0.5% of Cu, almost complete CBZ degradation was observed in 40 min of the photodegradation process. Finally, the combination of the photodegradation process with the activation of peroxymonosulphate (PMS) by Cu-TiO2/Ti3C2 resulted in markedly improved carbamazepine degradation and reached 100% within 20 min under simulated solar light irradiation. The degradation mechanism of CBZ was proposed based on trapping experiments, which revealed that •O2− and •SO4− are the main oxidising species involved in carbamazepine degradation. Moreover, the hybrid system exhibited high recyclability and stability during subsequent photodegradation cycles.

Applicability of NH2-MOF235(Fe)-derived α-Fe2O3/ZnO photocatalyst synthesized by the microwave-assisted method in the degradation of a mixture of phenolic compounds

The NH2-MOF235(Fe)-derived α-Fe2O3-X%/ZnO (X = 15, 20, and 25 wt%) composites were successfully synthesized by microwave-assisted method followed by calcination at 450 °C. The materials were evaluated on the photocatalytic degradation of bisphenol A (BPA), 4-tert-butylphenol (4tBP), and 4-tert-octylphenol (4tOP) mixture (5 mg/L, each) under solar simulated radiation. The synthesized materials were characterized by XRD, FTIR, N2 physisorption analysis, SEM-EDS, XPS, and electrochemical assays. The NH2-MOF235(Fe)-derived α-Fe2O3 incorporation during the ZnO synthesis led to an increase in the specific surface area, improved light absorption in the visible region of the spectrum, and efficient separation of photogenerated charges. Based on the face-centered central composite experimental design matrix and RSM (response surface methodology), the optimal conditions for mineralization of the endocrine-disrupting compound mixture (42.52%) were reached using α-Fe2O3-15%/ZnO photocatalyst at pH 7.0 in 330 min (600 kJ m−2 of accumulated radiation). Moreover, 85.33, 92.82, and 92.72% degradation percentages were obtained for 4tBP, 4tOP, and BPA, respectively. Acetic acid and 2,4-di-tert-butylphenol were the main detected by-products at the end of the treatment. The α-Fe2O3-15%/ZnO material was stable for three reuse cycles for the photocatalytic degradation of the endocrine-disrupting compounds mixture. The scavenger study showed that the O2●- followed by the ●OH radical and photogenerated h+ were the main reactive species involved in the degradation of the contaminants mixture. The Vibrio fischeri assay showed that the obtained effluent was non-toxic. NH2-MOF235(Fe)-derived α-Fe2O3 improves the properties of ZnO, resulting in a promising material to eliminate BPA, 4tBP, and 4tOP mixture from aqueous samples.

Assessing the Efficacy of A Mo2C/Peroxydisulfate System for Tertiary Wastewater Treatment: A Study of Losartan Degradation, E. coli Inactivation, and Synergistic Effects

This work examines the use of pristine Mo2C as an intriguing sodium persulfate (SPS) activator for the degradation of the drug losartan (LOS). Using 500 mg/L Mo2C and 250 mg/L SPS, 500 μg/L LOS was degraded in less than 45 min. LOS decomposition was enhanced in acidic pH, while the apparent kinetic constant decreased with higher LOS concentrations. According to experiments conducted in the presence of scavengers of reactive species, sulfate radicals, hydroxyl radicals, and singlet oxygen participated in LOS oxidation, with the latter being the predominant reactive species. The presence of competitors such as bicarbonate and organic matter reduced the observed efficiency in actual matrices, while, interestingly, the addition of chloride accelerated the degradation rate. The catalyst showed remarkable stability, with complete LOS removal being retained after five sequential experiments. The system was examined for simultaneous LOS decomposition and elimination of Escherichia coli. The presence of E. coli retarded LOS destruction, resulting in only 30% removal after 3 h, while the system was capable of reducing E. coli concentration by 1.23 log. However, in the presence of simulated solar irradiation, E. coli was reduced by almost 4 log and LOS was completely degraded in 45 min, revealing a significant synergistic effect of the solar/Mo2C/SPS system.

Evaluation of human skin response to solar-simulated radiation in an ex vivo model: Effects and photoprotection of L-Carnosine.

Sunlight, and more specifically the UV component, induces several skin damages, including sunburns, erythema and photoaging. The purpose of this work is to set up an ex vivo human skin model to assess the capacity of active principles in protecting skin from the deleterious effects of solar radiation. Ex vivo human skin biopsies were cultured in an air-liquid interface and exposed to solar-simulated radiation (SSR, 300-750 nm). L-Carnosine (0.2% and 2%) was applied topically to be tested as photoprotective compound. The effect on oxidative stress induction, photoaging and skin transcriptional profile was assessed by evaluating reactive oxygen species, advanced glycosylation end products formation and gene expression changes. In our model, SSR increases ROS production and AGE accumulation and affects the expression of genes related to oxidative stress, pigmentation, immunity, inflammation and photoaging. Among these pathways, 11 genes were selected as biomarkers to evaluate the skin solar radiation response. Results showed that L-Carnosine provides effective prevention against solar radiation damages reducing ROS, AGEs and mitigating the modulation of the selected biomarker genes. In conclusion, we report that our ex vivo skin model is a valuable system to assess the consequences of solar light exposure and the capacity of topically applied L-Carnosine to counteract them.

Development of bismuth-rich bismuth oxyhalides based photocatalyst for degradation of a representative antibiotic under simulated solar light irradiation

In this study, the novel 2D/2D S-scheme Bi12O15Cl6/BiOCl heterojunction was fabricated using a facile solvothermal followed by a post-thermal treatment process. The samples were characterized by various modern spectroscopy techniques. A series of Bi12O15Cl6/BiOCl heterojunctions were prepared by adjusting the molar ratio of Bi:Cl and the calcination temperature. The crystalline structure, morphology, elemental composition, and optical properties of nanocomposites strongly depend on the synthesis conditions. The sample prepared with Bi:Cl molar ratio of 2.0:1 and calcined at 400 °C (BOC-2.0-400) containing 29.55 wt% of BiOCl and 70.45 wt% of Bi12O15Cl6, exhibited the highest efficiency in the degradation of CIP solution under simulated solar light irradiation. The reaction rate constant was 2.5 times and 1.8 times higher than that of pristine BiOCl and Bi12O15Cl6, respectively. Under the experimental conditions of catalyst dosage of 0.7 gL-1, initial CIP concentration of 10 mgL-1 and pH8.8, CIP was completely degraded within 150 min of irradiation over the BOC-2.0-400. Furthermore, radical scavenging studies signified that O2●–, h+ are evolved in photocatalytic process. The experimental and characterization results provided evidenc that the excellent photocatalytic performance of Bi12O15Cl6/BiOCl heterojunction was facilitated by the construction of S-scheme charge transfer route with compact interface of 2D/2D morphology. The S-scheme Bi12O15Cl6/BiOCl heterojunction exhibited excellent visible light absorption ability, high photogenerated charge separation efficiency and maintained strong redox capacity for electrons and holes during CIP photodegradation. These findings provide a potential strategy for designing S-scheme heterojunction-based bismuth-rich bismuth oxyhalide photocatalyst to eliminate antibiotic residues.

Immobilization of a new copper (II) complex dye with multi-walled carbon nanotubes and functional simulation in dye-sensitized solar cell

ABSTRACT Dye-sensitized solar cells (DSSCs) are third-generation photovoltaics as an alternative and eco-friendly energy production method. Sensitizer dyes are the main component of DSSC which can increase their efficiency and optical response level. So, the optimal selection of sensitizers is critical for the better performance of solar cells. Recently, the use of more easily accessible metals such as copper in DSSCs has been investigated, especially for indoor uses under ambient light sources. Nevertheless, more work needs to prepare stable and highly efficient DSSCs. In the present study, a new ligand has been synthesized by 2,2′- bipyridine-4,4′-dicarboxylic acid and multiwalled carbon nanotubes (H2bpdc@ MWCNTs) and then complexed with a novel dye from alizarin and para-nitroaniline through Cu (II). The structural and optical properties of the product were evaluated for employment in dye-sensitized solar cells (DSSCs). The novel dye was fully characterized using 1H NMR, UV-Vis, and also Raman spectroscopy. The proposed DSSCs based on Cu- H2bpdc-Dye@ multiwalled carbon nanotubes were designed and modeled using COMSOL Multiphysics software. For this purpose, the complex refractive index of Cu H2bpdc-Dye@ MWCNT solar cell was determined using spectroscopic ellipsometry. It represents a unique and high refractive index, reaching 2.13 at 475 nm. The current–voltage curve and electrical parameters of the ITO/Cu- H2bpdc-Dye@MWCNTs/TiO2/ITO structure were calculated using COMSOL software. This DSSC based on Cu-H2bpdc-Dye @MWCNTs thin layer achieved 10.51% of η(JSC = 16.8 mA cm−2, VOC = 0.85 V, and FF = 73.6%) under simulated solar irradiation. It can be considered a potential candidate for employment in a new generation of dye-sensitized solar cells instead of the rare heavy metal-based dyes in DSSCs.

Phototransformation of phosphite induced by zinc oxide nanoparticles (ZnO NPs) in aquatic environments

Phosphite, an essential component in the biogeochemical phosphorus cycle, may make significant contributions to the bioavailable phosphorus pool as well as water eutrophication. However, to date, the potential impacts of coexisting photochemically active substances on the environmental fate and transformation of phosphite in aquatic environments have been sparsely elucidated. In the present study, the effect of zinc oxide nanoparticles (ZnO NPs), a widely distributed photocatalyst in aquatic environments, on phosphite phototransformation under simulated solar irradiation was systematically investigated. The physicochemical characteristics of the pristine and reacted ZnO NPs were thoroughly characterized. The results showed that the presence of ZnO NPs induced the indirect phototransformation of phosphite to phosphate, and the reaction rate increased with increasing ZnO NPs concentration. Through experiments with quenching and trapping free radicals, it was proved that photogenerated reactive oxygen species (ROS), such as hydroxyl radical (•OH), superoxide anion (O2•−), and singlet oxygen (1O2), made substantial contributions to phosphite phototransformation. In addition, the influencing factors such as initial phosphite concentration, pH, water matrixes (Cl−, F−, Br−, SO42−, NO3−, NO2−, HCO3−, humic acid (HA) and citric acid (CA)) were investigated. The component of generated precipitates after the phosphite phototransformation induced by ZnO NPs was still dominated by ZnO NPs, while the presence of amorphous Zn3(PO4)2 was identified. This work explored ZnO NPs-mediated phosphite phototransformation processes, indicating that nanophotocatalysts released into aquatic environments such as ZnO NPs may function as photosensitizers to play a beneficial role in the transformation of phosphite to phosphate, thereby potentially mitigating the toxicity of phosphite to aquatic organisms while exacerbating eutrophication. The findings of this study provide a novel insight into the comprehensive assessment of the environmental fate, potential ecological risk, and biogeochemical behaviors of phosphite in natural aquatic environments under the condition of combined pollution.

Photoactive Electrocatalyst with Staggered p-n Heterojunction for Rechargeable Zn-Air Batteries

Rechargeable zinc-air batteries (RZBs) demonstrate significant potential as next-generation batteries as they are non-flammable, resource-abundant, cost-efficient, feasible for ambient air operation, and have remarkable theoretical energy density (1086 Wh kg-1). However, the development of RZBs needs to address many challenges to speed up their commercialization. For example, low round-trip efficiency during cycling is caused by retarded reactivity of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air cathode. An air cathode with deficient electrocatalytic kinetics creates a large voltage gap, especially when the practical charge voltage is > 2.0 V, during the charging and discharging process. Moreover, the cycle life of the RZBs is limited owing to the structural degradation of air cathodes working under high charge voltage. Therefore, it is essential to improve both the round-trip efficiency and structural durability of air cathodes to ensure further development and commercialization of RZBs. For efficient energy generation and storage, photo-enhanced RZBs that combine photochemical and electrochemical energy conversion and storage with the help of solar energy, are a promising research focus. Photo-enhanced RZBs require a photoactive OER/ORR bifunctional cathode that is not merely an electrochemical catalyst but also a photo-active catalyst.In the present study, we developed a photoactive bifunctional air-electrocatalyst with a staggered p-n heterojunction band gap structure, comprising n-type g-C3N4 and p-type copper-doped ZIF-67 (CuZIF-67) composite, to accelerate sluggish OER/ORR processes via a durable structure and stable long-cycle-life performance for photo-enhanced RZBs. g-C3N4/CuZIF-67 has a suitable band gap, which ensures wide-range light absorption in the UV–Vis–NIR region, and stimulates more electrons to participate in ORR/OER electrocatalytic activity. Besides, it has a staggered bandgap structure and a BEF at the p-n junction of the catalyst, which improves electron–hole pairs separation efficiency, lowers overpotential, promotes ORR/OER electrocatalytic activity, and eventually enhances the efficiency of RZBs (the voltage gap was significantly decreased by 14% with simulated solar light irradiation). Moreover, a high concentration of pyrrolic-N groups in the cathode material, resulting in the excellent electrochemical durability of RZBs during charge/discharge cycles. The photo-enhanced RZB based on the g-C3N4/CuZIF-67 bifunctional catalyst exhibits good round-trip efficiency of 60% (2 mA cm-2) with a significantly decreased voltage gap (from 0.92 to 0.81 V) after 1000 cycles, under simulated solar light irradiation. It can be concluded that staggered p-n heterojunction and pyrrolic nitrogen-rich groups play an important role in efficient and durable photo-enhanced Zn-air batteries.

Constructing BiOCl nanosheets on BiOBr nanoplates by NH4Cl etching with enhanced photocatalytic H2O2 production performance

BiOCl/BiOBr heterojunction was designed by NH4Cl etching method to enhance photocatalytic H2O2 production. BiOCl nanosheeets were firmly in-situ generated on the surface of BiOBr nanoplates after treating BiOBr with NH4Cl, forming an effective Z-type heterojunction. The photocatalytic system can achieve a considerable productivity of H2O2 to 2604.11 μmol/g/h under simulated solar irradiation, which can be explained that BiOCl/BiOBr heterojunction improve the separation and migration ability of photocarriers, thus accelerating the photocatalytic H2O2 production process.

Photo-thermal conversion properties of Cr, Mo, and W nanofluids in polyethylene glycol prepared by laser ablation in liquid method for direct absorption solar collectors applications

Nanofluids (NFs) are promising materials for solar-energy harvesting. The main drawback of NFs is their instability and longtime preparation methods that the purpose of this work relies on overcoming these problems. The Cr, Mo, and W NFs in polyethylene glycol (PEG) were synthesized by laser ablation in liquid (LAL). The capability of the prepared NFs in photo-thermal conversion was investigated under 60 min solar simulator irradiation at 1 Sun and thermo-physical properties of them (SER, Etotal, E%, and B) were calculated, indicating Cr NF has the highest photo-thermal conversion efficiency (E%≅85% at its near-to-surface). The comparison of nanoparticles radius obtained with transmission electron microscopy (TEM) and the hydrodynamic radius obtained with dynamic light scattering (DLS) methods, reveals that nanoparticles were surrounded by a thick layer of PEG molecules, leading to the super-stable and long-life NFs. The effect of the nanoparticle concentration, light intensity, and consecutive heating–cooling cycles on the performance of NFs was investigated. Under 1 h sunlight illumination (∼850–960 W/m2 intensity), the surface temperature of Cr NF reaches ≅ 65 ℃, indicating the Cr NF is highly eligible for photo-thermal conversion in the real outdoor condition. The low cost and simplicity of the synthesis method, no need to use stabilizer, super durability, high-thermal stability, low rate constant of heat dissipation, and high photo-thermal conversion efficiency confirms that Cr/PEG NF can be used as potential working fluid for direct absorption solar collectors (DASCs).