Interfacial band offset engineering with barium-doping towards enhanced performance of all inorganic CsPbI2Br perovskite solar cells.

This study investigates the incorporation of Ba2+ at a low concentration into CsPbI2Br, resulting in the formation of mixed CsPb1-xBaxI2Br perovskite films. Photovoltaic devices utilizing these Ba-doped CsPbI2Br (Ba-CsPbI2Br) perovskite films achieved a higher stabilized power conversion efficiency of 14.07% compared to 11.60% for pure CsPbI2Br films. First-principles density functional theory calculations indicate that the improved device performance can be attributed to the efficient transport of conduction electrons across the interface between Ba-CsPbI2Br and the TiO2 electron transporting layer (ETL). The Ba-CsPbI2Br/TiO2 interface exhibits a type-II staggered band alignment with a smaller conduction band offset (CBO) of 0.25 eV, in contrast to the CsPbI2Br/TiO2 interface with a CBO of 0.48 eV. The reduced CBO at the Ba-CsPbI2Br/TiO2 interface diminishes the barrier for conduction electrons to transfer from the Ba-CsPbI2Br layer to the TiO2 layer, facilitating efficient charge transport.

A Review on Heavy Metal Ions and Containing Dyes Removal Through Graphene Oxide-Based Adsorption Strategies for Textile Wastewater Treatment.

Textile wastewater heavy metal pollution has become a severe environmental problem worldwide. Metal ion inclusion in a dye molecule exhibits a bathochromic shift producing deeper but duller shades, which provides excellent colouration. The ejection of a massive volume of wastewater containing heavy metal ions such as Cr (VI), Pb (II), Cd (II) and Zn (II) and metal-containing dyes are an unavoidable consequence because the textile industry consumes large quantities of water and all these chemicals cannot be combined entirely with fibres during the dyeing process. These high concentrations of chemicals in effluents interfere with the natural water resources, cause severe toxicological implications on the environment with a dramatic impact on human health. This article reviewed the various metal-containing dye types and their heavy metal ions pollution from entryway to the wastewater, which then briefly explored the effects on human health and the environment. Graphene-based absorbers, specially graphene oxide (GO) benefits from an ordered structured, high specific surface area, and flexible surface functionalization options, which are indispensable to realize a high performance of heavy metal ion removal. These exceptional adsorption properties of graphene-based materials support a position of ubiquity in our everyday lives. The collective representation of the textile wastewater's effective remediation methods is discussed and focused on the GO-based adsorption methods. Understanding the critical impact regarding the GO-based materials established adsorption portfolio for heavy metal ions removal are also discussed. Various heavy-metal ions and their pollutant effect, ways to remove such heavy metal ions and role of graphene-based adsorbent including their demand, perspective, limitation, and relative scopes are discussed elaborately in the review.

Incorporating Solution-Processed Mesoporous WO3 as an Interfacial Cathode Buffer Layer for Photovoltaic Applications.

Dextran-templating hydrothermal synthesis of monoclinic WO3 exhibits excellent specific surface area of ∼110 m2/g and a monomodal pore distribution with an average pore diameter of ∼20 nm. Dextran plays a crucial role in generating porosity on WO3. The role of supporting dextran has been investigated and found to be crucial to tune the surface area, porosity, and morphology. The photoluminescence and X-ray photoelectron spectroscopy studies reveal the existence of oxygen vacancies in substoichiometric WO3, which creates localized defect states in WO3 as synthesized through this templating method. The highly mesoporous WO3 has been further explored as an interfacial cathode buffer layer (CBL) in dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). A significantly enhanced photoconversion efficiency has boosted up the performance of the counter electrode used in traditional DSSC (as platinum) and PSC (as carbon) devices by ∼48 and ∼29%, respectively. The electrochemical impedance and incident photon to current conversion efficiency (IPCE) studies were also analyzed in order to understand the catalytic behavior of the WO3 interfacial CBL for both DSSCs and PSCs, respectively. The much higher surface area of WO3 enables rapid electron hopping mechanism, which further benefits for higher electron mobility, resulting in higher short circuit current. Through this study, we were able to unequivocally establish the importance of buffer layer incorporation, which can further help to integrate the DSSC and PSC devices toward more stable, reliable, and enhanced efficiency-generating devices. In spite of this, using WO3 constitutes an important step toward the efficiency improvement of the devices for futuristic photoelectrochromic or self-powered switchable glazing for low-energy adaptive building integration.

Fluorescent carbon nanoparticles from Citrus sinensis as efficient sorbents for pollutant dyes.

Here, we report a simple, green and economic process for the synthesis of highly fluorescent carbon nanoparticles (CPs) through low-temperature carbonization of a fruit waste, Citrus sinensis peel. This approach allows the large-scale production of aqueous CPs dispersions without any additives and post-treatment processes. The as-prepared CPs were of small particle size, exhibited bright blue fluorescence under UV irradiation (λmax  = 365 nm) with excellent colloidal stability in water. The chemical composition, structure and morphology of the as-prepared CPs were analyzed using various spectroscopic techniques such as X-ray diffraction, transmission electron microscopy and raman spectroscopy. The formed CPs were turbostratic in nature, with a large number of functional groups on the surface. We explored the adsorption characteristics of the formed CPs for wastewater treatment. Because of the negative surface of the CPs, as evident from the zeta value, it is possible to use them for selective adsorption of the cationic dye methylene blue from a mixture of dyes. The equilibrium adsorption isotherm revealed that the Langmuir model better describes the adsorption process than the Freundlich model. As-prepared CPs rapidly adsorbed ~84% of the methylene blue within 1 min and can be regenerated and used repeatedly. Copyright © 2016 John Wiley & Sons, Ltd.

Enhanced stability of Zn2SnO4 with N719, N3 and eosin Y dye molecules for DSSC application.

In view of the increased prospects of Zn2SnO4 as an alternative photoanode for dye sensitized solar cells (DSSCs), we synthesized phase pure Zn2SnO4 nanostructures by a cost effective sonochemical technique. In order to establish the stability of this alternative photoanode in DSSCs, we further explored the interaction of the synthesized Zn2SnO4 with commonly used photosensitizers in DSSCs, such as N3, N719 and eosin Y. Based on the time dependent optical studies we could establish the prominence of anchoring groups in controlling the dye loading. Optical studies confirmed an enhanced stable interaction of Zn2SnO4 with all the studied sensitizers which could be beneficial in designing DSSC devices in future. In addition, we also established contact angle measurement as an indirect tool to understand the surface characteristics and thereby optimize the dye loading and stability of the photoanode surface. With the help of contact angle data, we could unequivocally establish the stability of the Zn2SnO4 photoanode surface modified with N3 and N719 dye molecules. Our studies further suggest the enhanced and superior stability of the prepared Zn2SnO4 compared to ZnO in different chemical environments. The quenching of the fluorescence and the abrupt decrease in the contact angle owing to an increase in the surface roughness further strengthen the above conclusion. To our best knowledge, this probably is the first report on the synthesis of Zn2SnO4 by a sonochemical process and its interaction with various photosensitizers. An exceptionally high open circuit voltage of >0.8 V was observed for all the devices fabricated with the synthesized ZTO as a photoanode. Our studies could pave way to future developments in the area of DSSCs using Zn2SnO4 as a photoanode.

Selective detection of Escherichia coli DNA using fluorescent carbon spindles.

We investigate the interaction of hydrophilic blue emitting carbon spindles with various deoxyribonucleic acids (DNA) having different base pair compositions, such as Herring testes (HT), calf thymus (CT), Escherichia coli (EC) and Micrococcus lysodeikticus (ML) DNA, to understand the mode of interaction. Interestingly, the fluorescent carbon spindles selectively interacted with E. coli DNA resulting in enhanced fluorescence of the former. Interaction of the same carbon with other DNAs exhibited insignificant changes in fluorescence. In addition, in the presence of EC DNA, the D band in the Raman spectrum attributed to the defect state completely disappeared, resulting in enhanced crystallinity. Microscopy images confirmed the wrapping of DNA on the carbon spindles leading to the assembly of spindles in the form of flowers. Dissociation of double-stranded DNA occurred upon interaction with carbon spindles, resulting in selective E. coli DNA interaction. The carbon spindles also exhibited a similar fluorescence enhancement upon treating with E. coli bacteria. These results confirm the possibility of E. coli detection in water and other liquid foods using such fluorescent carbon.

Citric Acid Fuctionalized Magnetic Ferrite Nanoparticles for Photocatalytic Degradation of Azo Dye.

In this study different magnetic ferrite nanoparticles (MFe2O4, where M = Fe, Mn, Zn) were synthesized through an aqueous coprecipitation method and then functionalized with citric acid for the degradation of azo dye present in industrial waste water. Here we evaluated the role of citric acid for photocatalytic application. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the catalytic activity in degradation of methyl orange (MO) was evaluated. The rate of MO degradation in different magnetic systems was determined by UV-Vis spectroscopy. The effect of active parameters (pH, initial MO concentration and effect of sunlight) on degradation performance was investigated. For the first time, citric acid chemistry is successfully exploited to develop a photocatalyst that can successfully degrade the dyes. This citric acid functionalized magnetic ferrite nanoparticles are very much effective for photocalytic degradation of dye and also these can be recollected with the help of permanent magnet for successive uses.

Heterostructured WO3-TiVO4 thin-film photocatalyst for efficient photoelectrochemical water splitting.

Photoelectrochemical water splitting via solar irradiation has garnered significant interest due to its potential in large-scale renewable hydrogen production. Heterostructure materials have emerged as an effective strategy, demonstrating enhanced performance in photoelectrochemical water-splitting applications compared to individual photocatalysts. In this study, to augment the performance of sprayed TiVO4 thin films, a hydrothermally prepared WO3 underlayer was integrated beneath the spray pyrolised TiVO4 film. The consequent heterostructure demonstrated notable enhancements in optical, structural, microstructural attributes, and photocurrent properties. This improvement is attributed to the strategic deposition of WO3 underlayer, forming a heterostructure composite electrode. This led to a marked increase in photocurrent density for the WO3/TiVO4 photoanode, reaching a peak of 740 µA/cm2 at an applied potential of 1.23 V vs RHE, about nine-fold that of standalone TiVO4. Electrochemical impedance spectroscopy revealed a reduced semicircle for the heterostructure, indicating improved charge transfer compared to bare TiVO4. The heterostructure photoelectrode exhibited enhanced charge carrier conductivity at the interface and sustained stability over 3 h. The distinct attributes of heterostructure photoelectrode present significant opportunities for devising highly efficient sunlight-driven water-splitting systems.

Novel Au/Cu2NiSnS4 Nano-Heterostructure: Synthesis, Structure, Heterojunction Band Offset and Alignment, and Interfacial Charge Transfer Dynamics.

Considering the importance of physics and chemistry at material interfaces, we have explored the coupling of multinary chalcogenide semiconductor Cu2NiSnS4 nanoparticles (CNTS NPs) for the first time with the noble metal (Au) to form Au-CNTS nano-heterostructures (NHSs). The Au-CNTS NHSs is synthesized by a simple facile hot injection method. Synergistic experimental and theoretical approaches are employed to characterize the structural, optical, and electrical properties of the Au-CNTS NHSs. The absorption spectra demonstrate enhanced and broadened optical absorption in the ultraviolet-visible-near-infrared (UV-Vis-NIR) region, which is corroborated by cyclic voltammetry (CV) readings. CV measurements show type II staggered band alignment, with a conduction band offset (CBO) of 0.21 and 0.23 eV at the Au-CNTS/CdS and CNTS/CdS interface, respectively. Complementary first-principles density functional theory (DFT) calculations predict the formation of a stable Au-CNTS NHSs, with the Au nanoparticle transferring its electrons to the CNTS. Moreover, our interface analysis using ultrafast transient absorption experiments demonstrate that the Au-CNTS NHSs facilitates efficient transport and separation of photoexcited charge carriers when compared to pristine CNTS. The transient measurements further reveal a plasmonic electronic transfer from the Au nanoparticle to CNTS. Our advanced analysis and findings will prompt investigations into new functional materials and their photo/electrocatalysis and optoelectronic device applications in the future.

An overview of the tribological and mechanical properties of PEEK and CFR-PEEK for use in total joint replacements.

Poly-ether-ether-ketone (PEEK) and PEEK composites are outstanding candidates for biomedical applications, such as orthopedic devices, where biocompatibility and modulus match with surrounding tissue are requisite for long-term success. The mechanical properties can be optimized by incorporating fillers such as continuous and chopped carbon fibers. While much is known about the mechanical and tribological behavior of PEEK composites, there are few articles that summarize the viability of using PEEK reinforced with carbon fibers in orthopedic implants. This paper reviews biocompatibility, tribological, and mechanical studies on PEEK and their composites with carbon fibers, notably PEEK reinforced with polyacrylonitrile (PAN)-based carbon fibers and PEEK reinforced with pitch-based carbon fibers, for application in orthopedics and total joint replacements (TJRs). The main objectives of this review are two-fold. Firstly, this paper aims to assist designers in making informed decisions on the suitability of using PEEK and PEEK composites in orthopedic applications; as it is not well understood how these materials perform on the whole in orthopedics and TJRs. Secondly, this paper aims to serve as a centralized paper in which researchers can gain information on the tribological and mechanical advancements of PEEK and PEEK composites.

Shape-Stabilized PEGylated Silica Aerogel-Composite as an Energy Saving Building Material.

Balancing thermal and visual comfort in buildings necessitates effective insulation to counteract heat loss and gain, especially with temperature variances. One promising approach is to combine phase change materials, such as poly(ethylene glycol) (PEG), with high-performance insulators like silica aerogel (Siag). To bolster opto-thermal performance in building envelopes, we introduce a smart insulation composite material through PEG integration, i.e., PEGalyation with Siag. Central to this thermal behavior is the PEG's phase change properties, which foster a shape-stabilized framework with Siag through their porous confinement. Preliminary observations indicate notable capabilities of obstructing near-infrared light while preserving satisfactory visible transparency. An optimized Siag@PEG composite with 5% loading of PEG has the visible range transmission of ∼92%, a decrease of ∼72% in thermal conductivity which is lower than pure glass and PEG, leading to a temperature dependent switchable hydrophobic to hydrophilic wettability characteristics. As a prototype window, the thermal performance evaluation of the synthesized composite, through experimental and computational studies, shows a decrease in indoor temperature of ∼20% with a higher temperature difference of ∼20 °C between outdoor and indoor weather conditions. This lightweight composite can act as sponge media to fill inside the double-paned window and for retrofitting existing glazing to boost the energy efficiency of buildings with facile manufacturing and scalability.

Synergistic Photoelectrochemical and Photocatalytic Properties of the Cobalt Nanoparticles-Embedded TiVO4 Thin Film.

To optimize the semiconductor properties of TiVO4 thin films and enhance their performance, we incorporated cobalt nanoparticles as an effective co-catalyst consisting of a non-noble metal. Through an investigation into the impact of cobalt loading on spray pyrolyzed TiVO4 thin films, we observed a significant enhancement in the photoelectrochemical (PEC) performance. This was accomplished by carefully optimizing the concentrations of Co2+ (3 mM) to fabricate a composite electrode, resulting in a higher photocurrent density for the TiVO4:Co photoanode. When an applied potential of 1.23 V (vs RHE) was used, the photocurrent density reached 450 µA/cm2, approximately 5 times higher than that of bare TiVO4. We conducted a thorough characterization of the composite structure and optical properties. Additionally, electrochemical impedance spectroscopy analysis indicated that the TiVO4/Co thin film exhibited a smaller semicircle, indicating a significant improvement in charge transfer at the interface. In comparison to bare TiVO4, the TiVO4/Co composite exhibited a notable improvement in photocatalytic activity when degrading methylene blue (MB) dye, a widely employed model dye. Under light illumination, a TiVO4/Co thin film exhibited a notable dye degradation rate of 97% within a 45 min duration. The scalability of our fabrication method makes it suitable for large-area devices intended for sunlight-driven PEC seawater splitting studies.

Robust control of water quality in horizontal sub-surface flow wetlands using decentralized quantitative feedback theory based controller.

This paper addresses the regulation of water quality influencers such as Organic Nitrogen, Ammonia Nitrogen, Nitrate Nitrogen, Dissolved Organic Carbon and Dissolved Oxygen for a sub-surface flow horizontal wetland in a controlled environment. The plant uncertainty is quantified by using measurement data. The robust control of the process is achieved using a decentralized quantitative feedback theory based control strategy. The control structure also employs a feed-forward mechanism to minimize loop interactions and feedback control to ensure stability, tracking and disturbance rejection. The numerical simulations and hardware-in-loop implementation show that the performance specifications are robustly met.

Advancing Thermoelectric Materials: A Comprehensive Review Exploring the Significance of One-Dimensional Nano Structuring.

Amidst the global challenges posed by pollution, escalating energy expenses, and the imminent threat of global warming, the pursuit of sustainable energy solutions has become increasingly imperative. Thermoelectricity, a promising form of green energy, can harness waste heat and directly convert it into electricity. This technology has captivated attention for centuries due to its environmentally friendly characteristics, mechanical stability, versatility in size and substrate, and absence of moving components. Its applications span diverse domains, encompassing heat recovery, cooling, sensing, and operating at low and high temperatures. However, developing thermoelectric materials with high-performance efficiency faces obstacles such as high cost, toxicity, and reliance on rare-earth elements. To address these challenges, this comprehensive review encompasses pivotal aspects of thermoelectricity, including its historical context, fundamental operating principles, cutting-edge materials, and innovative strategies. In particular, the potential of one-dimensional nanostructuring is explored as a promising avenue for advancing thermoelectric technology. The concept of one-dimensional nanostructuring is extensively examined, encompassing various configurations and their impact on the thermoelectric properties of materials. The profound influence of one-dimensional nanostructuring on thermoelectric parameters is also thoroughly discussed. The review also provides a comprehensive overview of large-scale synthesis methods for one-dimensional thermoelectric materials, delving into the measurement of thermoelectric properties specific to such materials. Finally, the review concludes by outlining prospects and identifying potential directions for further advancements in the field.

Effectual visible light photocatalytic reduction of para-nitro phenol using reduced graphene oxide and ZnO composite.

Removing wastewater pollutants using semiconducting-based heterogeneous photocatalysis is an advantageous technique because it provides strong redox power charge carriers under sunlight irradiation. In this study, we synthesized a composite of reduced graphene oxide (rGO) and zinc oxide nanorods (ZnO) called rGO@ZnO. We established the formation of type II heterojunction composites by employing various physicochemical characterization techniques. To evaluate the photocatalytic performance of the synthesized rGO@ZnO composite, we tested it for reducing a common wastewater pollutant, para-nitro phenol (PNP), to para-amino phenol (PAP) under both ultraviolet (UV) and visible light irradiances. The rGOx@ZnO (x = 0.5-7 wt%) samples, comprising various weights of rGO, were investigated as potential photocatalysts for the reduction of PNP to PAP under visible light irradiation. Among the samples, rGO5@ZnO exhibited remarkable photocatalytic activity, achieving a PNP reduction efficiency of approximately 98% within a short duration of four minutes. These results demonstrate an effective strategy and provide fundamental insights into removing high-value-added organic water pollutants.

Fabrication and Characterization of Tantalum-Iron Composites for Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen evolution represents a transformative avenue in addressing the challenges of fossil fuels, heralding a renewable and pristine alternative to conventional fossil fuel-driven energy paradigms. Yet, a formidable challenge is crafting a high-efficacy, stable photocatalyst that optimizes solar energy transduction and charge partitioning even under adversarial conditions. Within the scope of this investigation, tantalum-iron heterojunction composites characterized by intricate, discoidal nanostructured materials were meticulously synthesized using a solvothermal-augmented calcination protocol. The X-ray diffraction, coupled with Rietveld refinements delineated the nuanced alterations in phase constitution and structural intricacies engendered by disparate calcination thermal regimes. An exhaustive study encompassing nano-morphology, electronic band attributes, bandgap dynamics, and a rigorous appraisal of their photocatalytic prowess has been executed for the composite array. Intriguingly, the specimen denoted as 1000-1, a heterojunction composite of TaO2/Ta2O5/FeTaO4, manifested an exemplary photocatalytic hydrogen evolution capacity, registering at 51.24 µmol/g, which eclipses its counterpart, 1100-1 (Ta2O5/FeTaO4), by an impressive margin. Such revelations amplify the prospective utility of these tantalum iron matrices, endorsing their candidacy as potent agents for sustainable hydrogen production via photocatalysis.

Role of vanadium ions substitution on spinel MnCo2O4 towards enhanced electrocatalytic activity for hydrogen generation.

Improving efficient electrocatalysts (ECs) for hydrogen generation through water splitting is of significant interest in tackling the upcoming energy crisis. Sustainable hydrogen generation is the primary prerequisite to realizing the future hydrogen economy. This work examines the electrocatalytic activity of hydrothermally prepared vanadium doped MnCo spinel oxide microspheres (MC), MnVxCo2-xO4 (Vx-MnCo MC, where x ≤ 0.4) in the HER (hydrogen evolution reaction) process. Magnetization measurements demonstrated a paramagnetic (at high temperatures) to a ferrimagnetic (at low temperatures) transition below the Curie temperature (Tc) in all the samples. The magnetization is found to intensify with the rising vanadium content of MCs. The optimized catalyst Vx-MnCo MCs (x = 0.3) outperformed other prepared ECs with a Tafel slope of 84 mV/dec, a low onset potential of 78.9 mV, and a low overpotential of 85.9 mV at a current density of 10 mA/cm2, respectively. The significantly improved HER performance of hydrothermally synthesized Vx-MnCo MCs (x = 0.3) is principally attributable to many exposed active sites, accelerated electron transport at the EC/electrolyte interface, and remarkable electron spectroscopy for chemical analysis (ECSA) value was found ~ 11.4 cm2. Moreover, the Vx-MnCo MCs (x = 0.3) electrode exhibited outstanding electrocatalytic stability after exposure to 1000 cyclic voltametric cycles and 36 h of chronoamperometric testing. Our results suggest a feasible route for developing earth-abundant transition metal oxide-based EC as a superior electrode for future water electrolysis applications.

Effective Hydrogen Production from Alkaline and Natural Seawater using WO3-x@CdS1-x Nanocomposite-Based Electrocatalysts.

Offshore hydrogen production through water electrolysis presents significant technical and economic challenges. Achieving an efficient hydrogen evolution reaction (HER) in alkaline and natural seawater environments remains daunting due to the sluggish kinetics of water dissociation. To address this issue, we synthesized electrocatalytic WO3-x@CdS1-x nanocomposites (WCSNCs) using ultrasonic-assisted laser irradiation. The synthesized WCSNCs with varying CdS contents were thoroughly characterized to investigate their structural, morphological, and electrochemical properties. Among the samples tested, the WCSNCs with 20 wt % CdS1-x in WO3-x (Wx@Sx-20%) exhibited superior electrocatalytic performance for hydrogen evolution in a 1 M KOH solution. Specifically, the Wx@Sx-20% catalyst demonstrated an overpotential of 0.191 V at a current density of -10 mA/cm2 and a Tafel slope of 61.9 mV/dec. The Wx@Sx-20% catalysts demonstrated outstanding stability and durability, maintaining their performance after 24 h and up to 1000 CV cycles. Notably, when subjected to natural seawater electrolysis, the Wx@Sx-20% catalysts outperformed in terms of electrocatalytic HER activity and stability. The remarkable performance enhancement of the prepared electrocatalyst can be attributed to the combined effect of sulfur vacancies in CdS1-x and oxygen vacancies in WO3-x. These vacancies promote the electrochemically active surface area, enhance the rate of charge separation and transfer, increase the number of electrocatalytic active sites, and accelerate the HER process in alkaline and natural seawater environments.

Certified high-efficiency "large-area" perovskite solar module for Fresnel lens-based concentrated photovoltaics.

The future of energy generation is well in tune with the critical needs of the global economy, leading to more green innovations and emissions-abatement technologies. Introducing concentrated photovoltaics (CPVs) is one of the most promising technologies owing to its high photo-conversion efficiency. Although most researchers use silicon and cadmium telluride for CPV, we investigate the potential in nascent technologies, such as perovskite solar cell (PSC). This work constitutes a preliminary investigation into a "large-area" PSC module under a Fresnel lens (FL) with a "refractive optical concentrator-silicon-on-glass" base to minimize the PV performance and scalability trade-off concerning the PSCs. The FL-PSC system measured the solar current-voltage characteristics in variable lens-to-cell distances and illuminations. The PSC module temperature was systematically studied using the COMSOL transient heat transfer mechanism. The FL-based technique for "large-area" PSC architectures is a promising technology that further facilitates the potential for commercialization.

A nonenzymatic reduced graphene oxide-based nanosensor for parathion.

Organophosphate-based pesticides (e.g., parathion (PT)) have toxic effects on human health through their residues. Therefore, cost-effective and rapid detection strategies need to be developed to ensure the consuming food is free of any organophosphate-residue. This work proposed the fabrication of a robust, nonenzymatic electrochemical-sensing electrode modified with electrochemically reduced graphene oxide (ERGO) to detect PT residues in environmental samples (e.g., soil, water) as well as in vegetables and cereals. The ERGO sensor shows a significantly affected electrocatalytic reduction peak at -0.58 V (vs Ag/AgCl) for rapid quantification of PT due to the amplified electroactive surface area of the modified electrode. At optimized experimental conditions, square-wave voltammetric analysis exhibits higher sensitivity (50.5 µA·µM-1·cm-2), excellent selectivity, excellent stability (≈180 days), good reproducibility, and repeatability for interference-free detection of PT residues in actual samples. This electrochemical nanosensor is suitable for point-of-care detection of PT in a wide dynamic range of 3 × 10-11-11 × 10-6 M with a lower detection limit of 10.9 pM. The performance of the nanosensor was validated by adding PT to natural samples and comparing the data via absorption spectroscopy. PT detection results encourage the design of easy-to-use nanosensor-based analytical tools for rapidly monitoring other environmental samples.