Simple sonochemical synthesis of lanthanum tungstate (La2(WO4)3) nanoparticles as an enhanced electrocatalyst for the selective electrochemical determination of anti-scald-inhibitor diphenylamine

Selective and sensitive Electrocatalytic behavior of hierarchical SnS decorated on La2Sn2O7 embedded carbon nanofibers for detection of antioxidant diphenylamine in fruits samples

Diphenylamine (DPA) serves as an inhibitor to manage several infections and naturally occurring terpenes on fruits, which can be injurious to animals and humans. In this study, we developed tin sulfide (SnS) decorated on carbon nanofibers (CF) embedded with lanthanum stannate (La₂Sn₂O₇) and modified on glassy carbon electrodes (GCEs). Decorating the CF-LS with a SnS enhances electron transfer and introduces additional adsorption sites, facilitating the adsorption and catalytic dissociation of O2 molecules, thereby improving target sensitivity and selectivity. The sensor exhibited remarkable electrocatalytic activity, showing cathodic peak intensities at a potential of 0.58 V and an interfacial charge transfer resistance of 19.27 Ω. It displayed broad linear range (0.0125-803.825 μM), low detection limit (0.0044 nM), and high sensitivity (1.265 μA nM-1 cm-2). Furthermore, with relative standard deviation (RSD) of less than 2 %, the sensor showcased excellent repeatability, reproducibility, and stability. Real sample analysis of DPA in apples, red grapes, pears, and sweet tomatoes showed recovery rates (97.6-99.9 %), with an RSD below 2.5 %.

Highly Specific Non-Enzymatic Electrochemical Sensor for the Detection of Uric Acid Using Carboxylated Multiwalled Carbon Nanotubes Intertwined with GdS-Gd2O3 Nanoplates in Human Urine and Serum

Herein, the electrochemical sensing efficacy of carboxylic acid functionalized multiwalled carbon nanotubes (C-MWCNT) intertwined with coexisting phases of gadolinium monosulfide (GdS) and gadolinium oxide (Gd2O3) nanosheets is explored for the first time. The nanocomposite demonstrated splendid specificity for nonenzymatic electrochemical detection of uric acid (UA) in biological samples. It was synthesized using the coprecipitation method and thoroughly characterized. The presence of functional groups and disorder in the as-synthesized nanocomposite are confirmed using Fourier transform infrared spectroscopy and Raman spectroscopy. Furthermore, field emission scanning electron microscopy, high-resolution transmission electron microscope, X-ray powder diffraction, and X-ray photoelectron spectroscopy provides a clear understanding of the morphology, coexisting phases, and elemental composition of the as-synthesized nanocomposites. The differential pulse voltammetry technique was utilized to elaborate the electrochemical sensing of UA using a GdS-Gd2O3/C-MWCNT modified glassy carbon electrode (GCE), The sensor showed an enhanced current response by more than 2-fold compared to bare GCE. Also, the sensor's performance was further improved by dispersing the nanocomposite in an ionic liquid with the exceptional reproducibility (SD = 0.0025, n = 3). The fabricated UA sensor GdS-Gd2O3/C-MWCNT/IL/GCE demonstrated a wide linear detection range from 0.5-30 μM and 30-2000 μM, effectively covering the entire physiological range of UA in biological fluids with a limit of detection (LOD) of 0.380 μM (+3SD of blank) and a sensitivity of 356.125 μA mM-1 cm-2. Moreover, the electrodes exhibited storage stability for 2 weeks with decrease in zero-day current by only 4.5%. The sensor was validated by quantifying UA in 12 unprocessed clinical human urine and serum samples, and its comparison with the gold standard test yielded remarkable results (p < 0.05). Hence, the proposed nonenzymatic electrochemical UA sensor is selective, sensitive, reproducible, and stable, making it reliable for point-of-care diagnostics.

Voltammetric nano-molar range quantification of agrochemical pesticide using needle-like strontium pyrophosphate embedded on sulfur doped graphitic carbon nitride electrocatalyst

The development of a viable sensor for agrochemical pesticides requires the assessment of trace levels. To achieve this, we developed a diphenylamine (DPA) sensor using needle-like strontium pyrophosphate embedded in sulfur-doped graphitic carbon nitride (SrPO/SCN). We obtained needle-like SrPO/SCN nanocomposite through co-precipitation followed by ultrasonication. The formation of the SrPO/SCN nanocomposite was verified through FT-IR, XRD, XPS, SEM-EDX, and HR-TEM analyses. Additionally, we explored their electrochemical behavior towards DPA using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The SrPO/SCN nanocomposite-modified electrode exhibited a higher anodic peak current (15.47 µA) than those of the other modified and unmodified electrodes. Under optimal experimental conditions, SrPO/SCN/GCE demonstrated a good limit of detection (0.009 µmol/L), dynamic linear range (0.05-98 µmol/L), and sensitivity (0.36 µAµM-1cm-2). Furthermore, the developed sensor exhibited excellent reproducibility, selectivity, and stability, and successfully detected DPA in real samples, including pear and apple samples, with good recoveries.

The combined effects of lanthanum-modified bentonite and Vallisneria spiralis on phosphorus, dissolved organic matter, and heavy metal(loid)s

The use of lanthanum-modified bentonite (LMB) combined with Vallisneria spiralis (V∙s) (LMB + V∙s) is a common method for controlling internal phosphorus (P) release from sediments. However, the behaviors of iron (Fe) and manganese (Mn) under LMB + V∙s treatments, as well as the associated coupling effect on P, dissolved organic matter (DOM), and heavy metal(loid)s (HMs), require further investigations. Therefore, we used in this study a microelectrode system and high-resolution dialysis technology (HR-Peeper) to study the combined effects of LMB and V∙s on P, DOM, and HMs through a 66-day incubation experiment. The LMB + V∙s treatment increased the sediment DO concentration, promoting in-situ formations of Fe (III)/Mn (IV) oxyhydroxides, which, in turn, adsorbed P, soluble tungsten (W), DOM, and HMs. The increase in the concentrations of HCl-P, amorphous and poorly crystalline (oxyhydr) oxides-bound W, and oxidizable HMs forms demonstrated the capacity of the LMB + V∙s treatment to transform mobile P, W, and other HMs forms into more stable forms. The significant positive correlations between SRP, soluble W, UV254, and soluble Fe (II)/Mn, and the increased concentrations of the oxidizable HMs forms suggested the crucial role of the Fe/Mn redox in controlling the release of SRP, DOM, and HMs from sediments. The LMB + V∙s treatment resulted in SRP, W, and DOM removal rates of 74.49, 78.58, and 54.78 %, which were higher than those observed in the control group (without LMB and V∙s applications). On the other hand, the single and combined uses of LMB and V·s influenced the relative abundances of the sediment microbial communities without exhibiting effects on microbial diversity. This study demonstrated the key role of combined LMB and V∙s applications in controlling the release of P, W, DOM, and HMs in eutrophic lakes.

Boosting plant resilience: The promise of rare earth nanomaterials in growth, physiology, and stress mitigation

Rare earth elements (REE) have been extensively used in a variety of applications such as cell phones, electric vehicles, and lasers. REEs are also used as nanomaterials (NMs), which have distinctive features that make them suitable candidates for biomedical applications. In this review, we have highlighted the role of rare earth element nanomaterials (REE-NMs) in the growth of plants and physiology, including seed sprouting rate, shoot biomass, root biomass, and photosynthetic parameters. In addition, we discuss the role of REE-NMs in the biochemical and molecular responses of plants. Crucially, REE-NMs influence the primary metabolites of plants, namely sugars, amino acids, lipids, vitamins, enzymes, polyols, sorbitol, and mannitol, and secondary metabolites, like terpenoids, alkaloids, phenolics, and sulfur-containing compounds. Despite their protective effects, elevated concentrations of NMs are reported to induce toxicity and affect plant growth when compared with lower concentrations, and they not only induce toxicity in plants but also affect soil microbes, aquatic organisms, and humans via the food chain. Overall, we are still at an early stage of understanding the role of REE in plant physiology and growth, and it is essential to examine the interaction of nanoparticles with plant metabolites and their impact on the expression of plant genes and signaling networks.

A disposable voltammetric sensor for the determination of diphenylamine using modified pencil graphite electrode

This study reports the electrochemical monitoring and sensing of diphenylamine (DPA), an anti-scald agent on a modified pencil graphite electrode (PGE). DPA is also a potentially toxic environmental pollutant. A polymer of tyrosine synthesized by electrochemical process was utilized for the determination of DPA in real samples. The electrodes were characterized using IR, SEM, EDAX, AFM and EIS analyses. As far as we know, this is first time reporting the utilization of modified PGE via green approach for the monitoring of DPA. A dynamic linear range of 1.00-117.11 µM with a lower detection limit (LOD) of 0.7050 µM was showed by this sensor for the electrochemical quantification of DPA. The electrochemical oxidation of DPA on the modified sensor followed a mixed adsorption -diffusion controlled kinetics. The sensor also showed good anti-interference property for the determination of DPA in real samples. Furthermore, the developed sensor was applied for the selective sensing of DPA from real apple extracts with good recovery. The real sample analysis was validated with standard spectrophotometric method.

Self-calibrated HAp:Tb-EDTA paper-based probe with dual emission ratio fluorescence for binary visual and fluorescent detection of anthrax biomarker

Development of the portable device is significant for sensitive and rapid detection of an anthrax biomarker dipicolinic acid (DPA), existing in the B. anthracis. In this work, a novel HAp:Tb-EDTA paper-based ratiometric fluorescent sensor was obtained by a simple one-pot method for rapid and sensitive DPA detection. With the increased DPA concentration, the luminescence intensity of HAp (hydroxyapatite) remained constant, and thus applied as the stable reference signal, while the luminescence signal of Tb3+-EDTA was significantly enhanced due to the antenna effect. Therefore, the HAp:Tb-EDTA paper-based sensor was endowed with self-calibrated and ratiometric fluorescent detection performance for DPA. The proposed sensor showed excellent detection performance with a detection limit as low as 10.8 nM in the linear range of 0.5-30 μM. After combination with a smartphone, rapid visual and fluorescent detection of DPA was achieved. The proposed sensor was successfully applied to detect DPA from B. subtilis spore real samples, showing the application prospects of the paper-based sensors and opening a new horizon to develop novel paper-based point-of-care testing (POCT) devices.

La-doped NiWO4 coupled with reduced graphene oxide for effective electrochemical determination of diphenylamine

Diphenylamine (DPA) is a harmful pesticide widely used to control post-harvest scald of fruits. In this study, rapid and sensitive determination of DPA was realized by the development of an effective electrochemical sensor, which was fabricated by coupling La-doped NiWO4 nanoparticles (La/NiWO4) with reduced graphene oxide (rGO), and the obtained rGO/La/NiWO4 nanocomposite was modified on glassy carbon electrodes (GCEs). The morphologies, structures and compositions were well characterized, and the effects of La doping and the introduction of rGO on the crystal structure and electrochemical performance were discussed. The incorporation of both La and rGO was found to enhance the active surface area and improve conductivity, resulting in the enhanced electrocatalytic performance of rGO/La/NiWO4/GCE, including a wide linear range (0.01-500 μM), a low detection limit (0.0058 μM) and high sensitivity (1.778 μA μM-1 cm-2). The fabricated sensor was further used for DPA detection in fresh apple extract to evaluate its practicality and demonstrated excellent recoveries ranging from 99.52 to 104.70%.

Non-cytotoxic Dy3+ activated La10W22O81 nanophosphors for UV based cool white LEDs and anticancer applications

White-light-emitting La₁₀W₂₂O₈₁ (LWO): xDy³⁺ (0.5 ≤ x ≤ 10 mol%) nanocrystalline phosphors were developed by a facile hydrothermal assisted solid-state reaction. X-ray diffraction (XRD) pattern indicated that the prepared samples adopted orthorhombic crystal structures. The agglomeration of uniform nanorods was identified from the FE-SEM analysis of the optimized LWO: 1.5 mol% Dy³⁺ nanocrystalline phosphors. Additionally, transmission electron microscope, scanning transmission electron microscopy, selected area electron diffraction, and X-ray photoelectron spectroscopy were employed to explore the surface morphology, size, interplanar distance, and chemical composition with valence states of the LWO: 1.5 mol% Dy³⁺ phosphors, respectively. By exciting with 387 nm, the LWO: Dy³⁺ emission spectra showed two intense peaks at 476 nm (⁴F_9/2→⁶H_15/2) and 571 nm (⁴F_9/2→⁶H_13/2) and a shoulder peak at 659 nm (⁴F_9/2→⁶H_11/2). Optimum emission intensity was achieved for 1.5 mol% Dy³⁺ in the LWO host lattice. The luminescence quenching beyond 1.5 mol% Dy³⁺ is attributed to the dipole-dipole interactions when the Dy³⁺ (donor) and Dy³⁺ (acceptor) ions are at a critical distance of 58.53 Å. Photometric studies were conducted to evaluate the performance and practical applicability of the phosphors. The CIE chromaticity diagram suggests that the LWO: 1.5 mol% Dy³⁺ nanophosphor conspicuously exhibits cool white light. Therefore, this material could be a promising and potential white light-emitting nanocrystalline phosphor material for white light emitting diodes (LEDs) under near-UV excitation. In addition, the toxicity of the optimized nanophosphor in normal WI-38 lung fibroblast cells and MCF-7 breast cancer cells was examined. Surprisingly, LWO: 1.5 mol% Dy³⁺ nanophosphor was found to be non-cytotoxic to normal cells, but extremely toxic to cancer cells. Therefore, the nanophosphor materials can be considered potential candidates for biomedical applications, particularly for cancer treatment.

Integration of iron-manganese layered double hydroxide/tungsten carbide composite: An electrochemical tool for diphenylamine H•+ analysis in environmental samples

Incompetent governance of post-harvest horticultural crops especially apples and pears lead to numerous physiological storage disorders. In order to manage this issue, diphenylamine (DPA) is widely used as an antioxidant and anti-scald agent to preserve fruits from superficial scalds and degradation during storage. As a result, this research focuses on utilizing disposable electrodes constructed with sphere-shaped iron-manganese layered double hydroxide (FeMn-LDH) entrapped tungsten carbide (WC) nanocomposite on its electrochemical performances towards emergent food contaminant, DPA. The importance of the current work is the selection and design of hierarchically structured functional materials especially layered double hydroxides, in virtue of their outstanding properties. These multi-dimensional structures when introduced to form a composite with the highly beneficial tungsten carbide offer excellent characteristics such as exceptional accessibility to active sites, enhanced surface area, and high mass transport and diffusion which serves as advantageous for the electrochemical quantification of DPA. Furthermore, the synergy between FeMn-LDH and WC nanomaterials contributes to the higher active surface area, increased electrical conductivity, fast electron transportation, and ion diffusion, resulting in static properties including a wide linear range (0.01-183.34 μM), low detection limit (1.1 nM), greater sensitivity, selectivity, and reproducibility thus confirming the potential capability of the WC@FeMn-LDH sensor towards the interference-free determination of DPA which validates its practicality and feasibility in real-time. Hence, this work aims to stimulate the fabrication of various advanced hierarchical structures by a simple hydrothermal approach that can have veracity of potential applications.

A label-free electrochemical sensor constructed with layer-by-layer assembly of GCE-AuNPs-Q[7]·HAuCl4 for detection of diphenylamine

Metal-organic frameworks (MOFs) including cucurbit[7]uril block (Q[7]·HAuCl₄) were employed to develop a diphenylamine (DPA) sensor in electrochemical method, the presence of HAuCl₄ improved the conductivity of the macrocyclic compound. To further enhance of the sensitivity, Au nanoparticles were inserted between the surface of glassy carbon electrode and Q[7]·HAuCl₄ MOFs (GCE-AuNPs-Q[7]·HAuCl₄). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) were applied for evaluation on the electrochemical behavior. For the electrochemical inertness of DPA, a label-free electrochemical sensor in 5 mM K₃[Fe(CN)₆] solution was achieved, to produce a limit of detection as low as 4.6 µM in a linear range of 5-1000 µM with good reproducibility, high stability and acceptable anti-interference ability. Application of the proposed electrode for the quantitative determination of DPA in tap water and apple juice confirms its real value.

Surfactant-Assisted Synthesis of Praseodymium Orthovanadate Nanofiber-Supported NiFe-Layered Double Hydroxide Bifunctional Catalyst: The Electrochemical Detection and Degradation of Diphenylamine

Physiological storage disorders are caused by ineffective post-harvest handling of horticultural crops, particularly fruits. To address these post-harvest concerns, diphenylamine (DPAH^•+) is widely used as a preservative to prevent fruit degradation and surface scald during storage around the world. Humans are negatively affected by the use of high concentrations of DPAH^•+ because of the various health complications related to its exposure. As a result, accurate detection and quantification of DPAH^•+ residues in treated fruits are critical. Rare earth metal orthovanadates, which have excellent physical and chemical properties, are potential materials for electrochemical sensors in this area. Herein, we present a simple and direct ultrasonication technique for the surfactant-assisted synthesis of praseodymium orthovanadate (PrVO₄ or PrV) loaded on nickel iron layered double hydroxide (NiFe-LDH) synthesized with deep eutectic solvent assistance, as well as its application as an effective catalyst in the detection and degradation of DPAH^•+ in fruits and water samples. The current work presents supreme electrochemical features of a PrV@NiFe-LDH-modified screen-printed carbon electrode (SPCE) where cetyltrimethylammonium bromide (CTAB) surfactant-driven fabrication of PrV directs the formation of highly qualified engineered structures and the deep eutectic solvent based green synthesis of NiFe-LDH creates hierarchical lamellar structures following the principles of green chemistry. PrV and NiFe-LDH combine to produce a synergistic effect that improves the number of active sites, charge transfer kinetics, and electronic conductivity. Differential pulse voltammetry analysis of PrV@NiFe-LDH/SPCE reveals a dynamic working range (0.005-226.26 μM), increased sensitivity (133.13 μA μM^-1 cm^-2), enhanced photocatalytic activity, and low detection limit (0.001 μM), which are considered significant when compared with the former reported electrodes in the literature for the determination of DPAḢ⁺ for its real-time applications.

Electrocatalytic detection of noxious antioxidant diphenylamine in fruit samples with support of Cu@nanoporous carbon modified sensor

Herein, the facile synthesis of copper(II) and benzene-1,3,5-tricarboxylate (Cu-BTC) and copper nanoporous carbon (Cu@NPC) for the electrochemical detection of diphenylamine (DPA) was systematically investigated. The Cu-BTC and Cu@NPC materials structural, morphological, and thermal stability were evaluated and confirmed using FE-SEM, HR-TEM, XRD, FT-IR, and TGA. The electrocatalytic behavior of sensor materials was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It is presumed that the structural stability and synergic effect exhibited in Cu@NPC are favorable for enhanced sensitivity and selectivity towards the detection of DPA. The Cu@NPC exhibited a wide linear range (0.09-396.82 μM) and the lowest limit of detection (5 nM). Furthermore, the real sample analysis of the sensor for the detection of DPA in apples and pears confirms its potential capability in practical application.

Biocompatible Yb3+/Er3+ Co-activated La2(WO4)3 Upconversion Nanophosphors for Optical Thermometry, Biofluorescent, and Anticancer Agents

Non-cytotoxic upconversion nanocrystals are preferred candidates because they offer exceptional advantages for numerous applications, ranging from optical thermometry to bioimaging/biomedical applications. In this report, we demonstrate the luminescence characteristics and practical utility of a multifunctional upconversion nanophosphor based on Yb³⁺/Er³⁺:La₂(WO₄)₃ (LWO) flakes. Strong upconversion green emission was observed from 6-mol % Er³⁺-doped LWO nanophosphor flakes excited by a 980 nm laser. We further enhanced the upconversion emission considerably by co-doping LWO nanophosphors with Yb³⁺/Er³⁺ to exploit energy migration from Yb³⁺ to Er³⁺ ions. The exceptional improvement in upconversion green and near-infrared emission was achieved by Yb³⁺ ion co-doping up to 6 mol %; beyond 6 mol %, emission intensities remarkably dropped due to concentration quenching. Photometric parameters were evaluated with and without Yb³⁺ ion-doped LWO nanophosphors, which exhibited a high green color purity of 95.6%, to elucidate their energy transfer mechanism. In addition, temperature-dependent upconversion emission trends were evaluated by analyzing the fluorescence intensity ratio, exhibiting higher temperature sensitivity than that previously reported. This suggests the applicability of our proposed nanophosphors to optical thermometry. As for bioimaging applications, the non-cytotoxicity of the optimized nanophosphor was confirmed based on distinct fluorescence images of a normal fibroblast cell line (L929). Furthermore, we demonstrated the strong cytotoxicity of nanophosphors against human colon cancer (HCT-116) cells. Based on the results, non-cytotoxic Yb³⁺(6 mol %)/Er³⁺ (6 mol %):LWO upconversion nanophosphor flakes are expected to be exceptional candidates owing to their extensive suitability to the fields of upconversion lasers, optical thermometry, and biomedical and anticancer applications. The results indicate the potential of upconversion materials in the effective execution of multiple strategic applications.

Strontium tungstate-modified disposable strip for electrochemical detection of sulfadiazine in environmental samples

Rapid-monitoring of drugs has attracted tremendous consideration owing to robust global demand for cost-effective and high effectiveness. Binary metal oxides with various morphology have been reported as electrodes for electrochemical sensor to fulfilling the clinical and enviromental requirements. In this study, strontium tungstate (SrWO₄) nanoflakes have been successfully prepared via the facile sonochemical method for the first time. The characteristics of as-prepared SrWO₄ are systematically measured by various analytical and spectroscopic methods. The SrWO₄ nanoflakes are utilized to modify the electrochemical electrode for the sulfadiazine (SDZ) determination. The SrWO₄ modified electrode possesses excellent electrocatalytic activity and high recognition capability for the electrochemical detection of SDZ. Impressively, the as-fabricated SrWO₄ modified electrode attainted lowest oxidation peak at +0.93 V (vs Ag/AgCl₂) with the limit of detection of 0.009 μM, the sensitivity of 0.123 µA µM^-1 cm² and linear detection range of 0.05-235 μM. The enhanced performance of proposed SrWO₄-based sensors could be attributed to the catalytic effect, large surface area, good electrical conductivity and physicochemical nature. Notably, the electrocatalytic performances of the SDZ sensors are good as compared to the previous literature, indicating the significance of the newly designed SrWO₄ modified electrode. The real-sample diagnosis by the SDZ detection in environmental sample demonstrates the proposed SrWO₄-based sensors with good recovery range.

Sonochemical synthesis of samarium tungstate nanoparticles for the electrochemical detection of nilutamide

This study reports the sonochemical synthesis of samarium tungstate nanoparticles (SWNPs) for applications in electrochemical sensors. The synthesis process is based on a precipitation reaction, which was investigated by ultrasound and compared with the effect of stirring. A bath sonicator operated at a frequency and power of 37/100 kHz and ~60 W, respectively, was employed to prepare the material. The shock waves efficiently irradiated the reaction conditions as much as possible, resulting in the good crystallinity of the monoclinic phase of the SWNPs, which was confirmed by XRD analysis. The surface morphology and structural composition was further evaluated by HRTEM, EDS and XPS. The good crystallinity and uniform distribution of elements in the nanoparticles were confirmed. The performance of the SWNPs to electrochemically sense nilutamide (NLT) was studied, which revealed a good electrochemical signal. As a result, the SWNPs were applied to an electrode material for the detection of NLT. This study revealed the excellent activity of the SWNPs for NLT detection, resulting in a low detection limit (0.0026 µM) and good linear range (0.05-318 µM). Furthermore, the results show appreciable analytical performances, which could be applied to electrochemical anti-androgen drug nilutamide sensors.

Ratiometric fluorescence determination of hydrogen peroxide using carbon dot-embedded Ag@EuWO4(OH) nanocomposites

A sheet-like carbon dot-embedded Ag@EuWO₄(OH) luminescent nanoprobe was successfully developed for assaying hydrogen peroxide. Firstly, the carbon dot-embedded EuWO₄(OH) nanosheets were prepared in a Eu(NO₃)₃·6H₂O-(NH₄)₁₀H₂(W₂O₇)₆·xH₂O-CS(NH₂)₂ hydrothermal synthetic system. Subsequently, the carbon dot-embedded EuWO₄(OH) was functionalized by Ag nanoparticles using an in situ photochemical deposition strategy upon ultraviolet light irradiation. Taking advantage of the dual emissions of the luminescence from carbon dots and characteristic red transitions of Eu³⁺ ions in the integrated system, the carbon dot-embedded Ag@EuWO₄(OH) luminescent composites exhibit ratiometric fluorescence responsive activity towards hydrogen peroxide. The luminescent intensity ratio of Eu³⁺ (614 nm) to carbon dots (389 nm) shows a polynomial function with changing hydrogen peroxide concentration. The corresponding detection limit is 60 μM at a signal-to-noise ratio of 3 (S/N = 3) implying the potential use of the carbon dot-embedded Ag@EuWO₄(OH) as nanoprobe. The method was applied to the quantification of H₂O₂ in real samples with satisfactory results. Graphical abstract A carbon dot-embedded Ag@EuWO₄(OH) luminescence ratiometric probe was successfully prepared through hydrothermal method and in situ photochemical deposition strategy. The luminescence intensity ratio of Eu³⁺ to carbon dots shows synergistic luminescence response activity towards H₂O₂ with detection limit of 60 μM.

The facile co-precipitation synthesis of strontium tungstate anchored on a boron nitride (SrWO4/BN) composite as a promising electrocatalyst for pharmaceutical drug analysis

Strontium tungstate/boron nitride (SrWO₄/BN) composite considered efficient electrocatalysts in the area of electrochemical sensors.

Structural Insights on 2D Gadolinium Tungstate Nanoflake: A Promising Electrocatalyst for Sensor and Photocatalyst for the Degradation of Postharvest Fungicide (Carbendazim)

Gadolinium tungstate (Gd₂(WO₄)₃) has acquired much attention owing to its exclusive transport properties and excellent thermal and chemical stability. In this work, we demonstrate that two-dimensional (2D) gadolinium tungstate nanoflakes (GW Nfs) are synthesized by a coprecipitation method and represent novel architectures for efficient catalysis, which could be used in electrochemical sensing and photocatalytic degradation of the postharvest fungicide carbendazim (CBZ). The physicochemical properties of GW Nfs were studied by using XRD, Raman, TEM, EDX, and XPS, which show the formation of GW as a nanoflake-like structure with a well crystallized nature. The as-prepared GW Nfs revealed an admirable electrochemical response for CBZ detection with an LOD of 0.005 μM, a wide-ranging linear response of 0.02 to 40 μM, and a notable sensitivity of 0.39 μA μM^-1 cm^-2. Furthermore, the GW-Nf-modified electrode has a good recovery for CBZ in the study of real samples such as rice and soil washed water samples. Moreover, GW Nfs have a promising photocatalytic activity for CBZ degradation. The GW Nfs could degrade CBZ at greater than 98% efficiency and mineralize above 74% of the CBZ molecules in the presence of visible light irradiation with superior stability even after many cycles. Subsequently, the electrochemical and photocatalytic mechanisms were provided in detail.