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Creating cost-effective, chemically stable electrocatalysts to improve the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a major challenge in electrocatalytic water splitting. We synthesized a highly efficient NiFe-layered double hydroxide (LDH) electrocatalyst using a solvent-free method. The formation of well-interconnected metal ions with nanospherical architectures created an extensive electrochemically active surface area enriched with catalytically active sites, demonstrating synergistic effects. Preserving the suitable stoichiometric ratio, such as Ni6Fe4LDH, was crucial in enhancing the catalytic performance for both the HER and OER. The optimal Ni6Fe4LDH ratio established overpotentials of 167 mV (112 mV dec–1) for the HER and 280 mV (116 mV dec–1) for the OER, attaining a 10 mA cm–2current density in 1 M KOH. Moreover, Ni6Fe4LDH demonstrated impressive robustness, stable up to 90 h with a minor decrease of 4.1 and 4.6% in the current density for the HER and OER. Notably, in the bifunctional two-electrode arrangement of Ni6Fe4LDH/NF||Ni6Fe4LDH/NF, effective water electrolysis was accomplished, preserving a stable 10 mA cm–2current density at a bias of 1.64 V for over 140 h, with a slight current loss of 3.9% of the current density.

Graphical Abstract:

Developing low-cost, easily synthesizable, and incredibly efficient electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) has become essential for switching from nonrenewable energy to hydrogen fuel generation. Energy adaptation and storage required the creation of non-noble-metal electrocatalysts with admirable motion along with stability for water electrolysis. Cu@FeCN materials have been characterized using a variety of physical and electrochemical approaches, and the relationship between the materials and activity has been investigated. The newly developed Cu@FeCN electrode shows sustained stability and strong catalytic activity with enhanced electrochemical active surface area in line with H2O splitting maintaining an alkaline condition requiring a very short overpotential of only 320 mV at a current density of 20 mA/cm2with small Tafel slopes. Cu@FeCN has a computed TOF (turnover frequency) of 0.321 s–1, which is twice as high as the IrO2catalyst’s calculated TOF of 0.173 s–1at 1.60 V. This demonstrates that the Cu@FeCN catalyst is innately active for exceptional HER and OER performances as well as satisfying kinetics to overcome the lethargic water oxidation rate. At the anode (O2) and cathode (H2), respectively, at 1.54 V, solar-derived water electrolysis displays nonstop bubble formation.

MXenes, in view of their extraordinary properties, such as layered structure, metal-like high thermal stability, good mechanical strength, high conductivity, presence of active sites, and terminal functional groups, have received the utmost importance as outstanding materials for energy storage applications such as supercapacitors and metal-ion batteries. Even though MXenes have promising applications in Li-ion batteries due to their high Li-ion storage capacity, their performance is not satisfactory compared to the presently used state-of-the-art electrodes. Pure MXenes suffer from restacking of their sheets, and to overcome this issue and to enhance their performance, attempts have been made to modify their surfaces and/or surface terminal groups. Synthesis of MXene-based composites has produced attractive electroactive materials. The present review focuses on MXene-based electrode materials for applications in Li-ion batteries.

The utilization of doped WO3nanostructures as an active component in electrochemical sensors is a promising strategy for delivering highly sensitive and stable detection schemes. In this work, a nanostructured WO3possessing a mixture of nanoparticle and one-dimensional (1-D) architecture, doped with Ta, was synthesized via hydrothermal reaction for electrochemical sensor application. Substituting Ta in W lattice positions yields polymorphic crystals with n-type characteristics. An optimized Ta content of 2.02 at. % in WO3was utilized for detailed electrochemical analysis of diuron (DIU) and dichlone (DCN). An electrochemical sensor was fabricated by packing the mechanically intercalated Ta-WO3/carbon matrix into a Teflon tube. The developed Ta-WO3/CPE could be employed for the selective and sensitive electrocatalytic determination of DIU and DCN in the presence of the cationic surfactant, viz., CTAB. The CTAB-mediated Ta-WO3/CPE exhibited good linearity with remarkable detection limits of 5.2 and 0.4 nM for DIU and DCN, respectively. The sensor displayed good sensitivity of 4.8 (for DIU) and 38.7 μA·μM–1·cm–2(for DCN) with selectivity, demonstrating real-time efficiency for DIU and DCN determination in spiked soil and water samples with satisfactory results.

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The serotype-specific early detection of dengue fever is very effective in predicting the pervasiveness of fatal infections such as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). This fever results from reinfection (secondary) with a serotype of the dengue virus, which is different from the serotype involved in primary infection. Hence, the present work was aimed to develop a multiplexed electrochemical paper-based analytical device (ePAD) consisting of graphene oxide–silicon dioxide (GO-SiO2) nanocomposites to detect the specific type of dengue virus (DENV). The conducting nature of GO-SiO2-coated multiplexed platform provided amplification in the signal response of the genosensor. The present sensor detected the target DNA of the four serotypes of the dengue virus, namely, DENV 1, DENV 2, DENV 3, and DENV 4, in a wide detection range of 100 pM to 100 μM. The sensor showed a high degree of specificity toward specific serotypes of DENV. Further, the use of such paper-based sensor had many advantages such as facile preparation, homogeneous distribution of nanoparticles onto the surface, requirement of a small quantity of sample, and low cost. To the best of our knowledge, this is the first report on the fabrication of a genosensor for predicting the pervasiveness of the dengue hemorrhagic fever or dengue shock syndrome.

Hydrogen is a viable clean energy source due to its high energy density and the fact that it burns without producing any carbon emissions. Nanostructured materials with tunable porosity have gathered significant attention for both hydrogen generation and hydrogen storage applications. This comprehensive review manuscript provides an in-depth overview of recent advancements in porosity tunability in nanostructures for hydrogen generation and hydrogen storage. With an emphasis on their porosity engineering tactics and their effects on hydrogen production efficiency and hydrogen storage capacity, it covers the synthesis procedures, characterization methodologies, and performance assessment of nanostructured materials. Sol-gel synthesis, hydrothermal synthesis, and chemical vapor deposition are the synthesis techniques covered in this paper. Through the careful control of nanostructured materials' size, shape, and composition, these techniques make it possible to precisely design porosity. These materials are characterized using methods like X-ray diffraction and scanning electron microscopy to examine their crystal structure and shape. When evaluating the performance of nanostructured materials, methods like gas chromatography are used to estimate the efficiency of hydrogen generation, and gravimetric and volumetric measurements are used to determine the hydrogen storage capacity. Overall, understanding porosity engineering strategies and their impact on hydrogen generation and storage is crucial for the development of efficient and sustainable energy systems. Furthermore, the challenges and prospects in this field are discussed, aiming to guide future research and development efforts towards efficient and sustainable hydrogen production and storage.

This study aims to develop a rapid, facile, and sensitive sensor for electroanalytical carbendazim (CAR) detection. A novel and simple sensor was fabricated by incorporating a composite matrix of titanium dioxide nanoparticles (TiO2-NPs) with reduced graphene oxide (rGO) loaded carbon paste within a polytetrafluoroethylene (PTFE) tube for investigation. Characterization of the synthesized TiO2-NPs was conducted using SEM, XRD, and AFM techniques to assess their structural, morphological and functional features that could support understanding the electrocatalytic activity at the modified sensor (CPE/rGO/TiO2). Comparative analysis with the carbon paste electrode (CPE) revealed that CPE/rGO/TiO2demonstrated sensitivity, achieving approximately a 6-fold higher detection current in CAR analysis. Cyclic voltammetry (CV), linear sweep voltammetry (LSV) and square wave voltammetry (SWV) approaches were employed for CAR's electrochemical detection and determination. The physicochemical attributes of the electrode activity were investigated under optimum experimental conditions, including electrolyte pH and accumulation time. The CPE/rGO/TiO2exhibited a limit of detection of 7.66nM, with a sensitivity of 1.08µA.µM−1.cm−2within a wide range of concentration linearity. The selectivity of CPE/rGO/TiO2against interference metal ions with CAR was assessed. In real-time applications, the developed electrode was tested for the analysis of CAR in spiked soil and water samples, demonstrating significant detection capacity with good recovery. Moreover, the electrode exhibited stability across multiple measurements, highlighting CPE/rGO/TiO2as a promising sensor for CAR detection.

Perfluoroalkyl carboxylic acids (PFCAs) exhibit high chemical and thermal stability, rendering them versatile for various applications. However, their notable toxicity poses environmental and human health concerns. Detecting trace amounts of these chemicals is crucial to mitigate risks. Electrochemical sensors surpass traditional methods in sensitivity, selectivity, and cost-effectiveness. In this study, a graphene nanosheet-based sensor was developed for detecting perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA). Using the Hummer method, graphene nanosheets were synthesized and characterized in terms of morphology, structural ordering, and surface topology. Ab initio molecular dynamics simulations determined the molecular interaction of per- and poly-fluoroalkyl substances (PFASs) with the sensor material. The sensor exhibited high sensitivity (50.75 μA·μM–1·cm–2for PFOA and 29.58 μA·μM–1·cm–2for PFDA) and low detection limits (10.4 nM for PFOA and 16.6 nM for PFDA) within the electrode dynamic linearity range of 0.05–500.0 μM (PFOA) and 0.08–500.0 μM (PFDA). Under optimal conditions, the sensor demonstrated excellent selectivity and recovery in testing for PFOA and PFDA in environmental samples, including spiked soil, water, spoiled vegetables, and fruit samples.

The development and creation of cost-effective, chemically robust electrocatalysts to aid in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) represent significant challenges within the realm of electrocatalytic water electrolysis. In this study, we synthesized a highly competent electroactive catalyst comprising nickel–iron-layered double hydroxide (LDH) using a simple hydrothermal approach. The resultant structure, characterized by well-interconnected metal ions arranged in nanospherical architectures, facilitated the formation of an enhanced electrochemical surface area rich in catalytically active sites, exhibiting harmonious effects. Maintaining the appropriate stoichiometric balance, exemplified by NiFe@LDH, proved essential in augmenting catalytic behavior for both OER and HER. The catalysts NiFe@LDH demonstrated overpotentials of 260 mV (76 mV dec–1) for OER and 138 mV (83 mV dec–1) for HER, achieving a current density of 10 mA cm–2in 1 M KOH. Furthermore, NiFe@LDH showcased remarkable durability, enduring up to 100 h with a marginal reduction in current densities of 4.2 and 3.2% for OER and HER, correspondingly. Significantly, in the bifunctional two-electrode configuration featuring NiFe@LDH/NF//NiFe@LDH/NF, efficient electrolysis was achieved, maintaining a stable 10 mA cm–2at a bias of 1.57 V for over 150 h, with a negligible of 4.6% current loss.

Health care monitoring is an extremely important aspect of human life that can be accomplished using wearable skin-patchable sensors. Upon interfacing with the skin or epidermal surface of the body, the sensing patches can monitor the movements of human parts such joints, legs, and fingers as well as tiny vibrations caused by respiration, blood flow, and heart beat. Wearable skin patches have shown improved promise in monitoring the body temperature and fever in addition to quick measurement of blood pressure and pulse rate along with breathing rate. Sensors can also analyze the sweat contents when in contact with the skin as well as other analytes such as diabetes-based volatile organic compounds (VOCs) and organophosphate nerve stimulating agents. Hence, the sensors can be of immense help in the early prediction of malfunctions of the body organs such as heart and lungs, leading to timely and effective treatment. This review covers different important aspects of skin-patchable sensors including mechanical strength and flexibility, sensitivity, transparency, self-healing, self-cleaning, and self-powering ability as well as their latest applications in medical technology.

The widespread use of pesticides in agriculture has led to significant environmental problems as well as complications with human health and hygiene. The current research focuses on developing the modified carbon-based nanostructured materials from Fe-doped tungsten oxide (WO3) as a modified sensor for the analysis of synthetic growth regulators (SGR), 2,4-dichloro phenoxy acetic acid (2,4-D), and 4-cholrophenoxy acetic acid (4-CPAA) by employing cyclic voltammetry (CV). The full characterizations of Fe-doped WO3nanoparticles were carried out to understand their morphology, dopant concentration, atomic distribution, and valence of each element. The electro-catalytic behavior, conducting, and large surface area of the tungsten oxide were responsible for the improvement of voltammetric signals compared to nascent CPE. The effect of pH was investigated at pH 3.0 for 4-CPAA, while pH 6.0 was used for 2,4-D. From the experimental data generated electro−kinetic and activation aspects were estimated by the impact of sweep rate and temperature. The square wave voltammetric (SWV) technique was employed to investigate 2,4-D with a lesser LOD of 6.28 × 10−8M (2,4-D), while that for 4-CPAA, the detection limit was 9.23 × 10−8M (4-CPAA). The developed method can be useful for the future analysis of various SGRs.

A novel electrochemical carbon paste sensor containing 10% magnesium doped with zinc oxide nanoparticles was developed and used for electrochemical detection of an anti-inflammatory drug, mefenamic acid. The electrode materials were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction. Electrochemical and square wave voltammetric techniques were employed to find the lowest possible limit of detection to quantify mefenamic acid. Analytical experiments were performed over the pH range of 3.0-11.2. The pH 7.0 was found to be suitable for the analysis in real samples of human urine as well as a pharmaceutical dosage form. The present work was compared with our early findings based on barium zinc oxide modified glassy carbon electrode to understand the effect of variation of dopant. The results suggested that the dopant significantly affected the electrochemical determination of the analyte and better results were obtained with the modified electrode.

Carbon-based resources introduced as sensing tools enormously in recent years for biomedical and biological applications. In the current research, a novel carbon-based material is proposed to study electrochemical nature of clozapine (CLZ), an antipsychotic drug. The proposed carbon matrix composed of synthesized Ru doped TiO2 (RuTiO2) nanoparticles and multiwall carbon nanotubes (MWCNTs). The surface characteristics of synthesized RuTiO2 were studied by utilizing Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM) followed by atomic force microscopy (AFM) study. The electrooxidation of CLZ was studied at RuTiO2, MWCNTs, and RuTiO2/MWCNTs composite modified carbon paste electrode (CPE) by cyclic voltammetry (CV) and square wave voltammetric (SWV) techniques. The influence of various physicochemical parameters on the signal enhancement of CLZ was studied. The concentration of CLZ was determined by the electrode in a wide concentration range of about 0.01 uM to 0.07 uM with LOD value of 0.057 nM. The practical electroanalytical application was conducted by carrying out quantification of CLZ in the analysis of clinical dosages and as well as in human urine samples.

A nano level voltammetric sensing method has been developed for determination of acyclovir (ACV) at nano clay modified carbon paste sensor by employing cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques in pH5.0. The electro-oxidation current of ACV was enhanced two times greater by the modification of the sensor. The modifier nano clay was characterized by utilizing X-ray diffraction (XRD) and scanning electronic microscope (SEM). The influence of parameters like scan rate, pH, accumulation time, amount of the modifier and concentration on the peak current of the drug were studied. The effect of ACV concentration variation was studied using SWV technique and got lowest detection limit compared to the earlier reported techniques. The fabricated sensor was employed for the determination of acyclovir in pharmaceutical and biological samples.

In the current research, ruthenium stood a conspicuous dopant for TiO2 nanoparticles, to enhance its catalytic activity. The characterization of synthesized nanoparticles was accomplished by utilizing XRD, SEM, EDX and TEM analysis. The sensing surface morphology was studied by AFM analysis. Further, we established the electrochemical behavior and detection of flufenamic acid (FFA) by utilizing ruthenium doped TiO2 nanoparticles modified carbon paste electrode (Ru-TiO2/CPE) at pH 6.0 by employing different voltammetric techniques. Modification enhances the electro-oxidation of flufenamic acid with increased current intensity. The influence of parameters like scan rate, pH, accumulation time, amount of the modifier and concentration on the peak current of the drug were studied. The effect of FFA concentration variation was studied using square wave voltammetric (SWV) technique and got lowest detection limit compared to reported techniques. The fabricated sensor was employed for the determination of flufenamic acid in biological samples.

A set of pyrimidine nucleobase present in all living systems as a component of nucleic acid constitutes uracil together with thymine and cytosine. A diverse physiological activity is exhibited by many N-substituted uracil derivatives. In oncology, 5-FU is widely used as an important anticancer drug. Electrochemical behavior was studied using cyclic voltammetric method, and the analytical application was studied using differential pulse voltammetric method. Solution pH has been measured by pH meter. The process on the surface of electrode was found to be irreversible and diffusion controlled. The charge transfer coefficient, heterogeneous rate constant, and the number of electron transferred were calculated. Possible reaction mechanism taking place on the surface of electrode was proposed. Calibration plot constructed using differential pulse voltammetric technique was used for quantitative analysis in pharmaceutical and human urine sample. Limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 12.25 and 40.8 nM, respectively. In the present work, we described the electrochemical behavior of anticancer drug and its determination in human urine and pharmaceutical samples. The method shows the development of a sensor for selective and sensitive determination of 5-FU.

The behavior of biomolecules and the advancements in the electrochemical techniques play a tremendous role in the development of voltammetric sensors. Redox reactions of biologically active molecules can be studied by using different voltammetry techniques which guide us to understand the metabolic fact of the targeted drug. In the present work, we describe the electrochemical oxidation of d-panthenol (DP) by using a versatile glassy carbon electrode (GCE). Experimental section was carried out by using cyclic voltammetry and square wave voltammetry. Under the optimized conditions (pH 4.2), the square wave voltammetric peak current of d-panthenol increased linearly with its concentration. The detection limit was found to be 5.0 × 10−7M. The number of protons and electrons involved in the oxidation process were calculated. The heterogeneous rate constant was found to be (3.67 × 103s−1). The method detects the trace level of the analyte with low detection limit which imparts the development of a sensor for selective and sensitive determination of d-panthenol. This sensor was successfully applied to determine the d-panthenol in spiked urine samples.

Among the transition metal chalcogenides, MoS2has been one of the most widely studied nanomaterials because of its interesting physico-chemical properties. Its layered structure and high surface-to-volume ratio have triggered much attention in energy storage area, resulting in numerous applications. Few review articles published in this area are MoS2and MoS2-based nanocomposites for energy storage applications, but virtually lesser reviews focusing on supercapacitor performance of MoS2are not available. Herein, we report the recent advances on MoS2based supercapacitors to understand how the research has improved its energy storage performance without the use of any composites of MoS2with other nanomaterials. A general overview of the conducting-semiconducting phases of MoS2, effect of doping in MoS2, and the status of MoS2in flexible as well as wearable supercapacitors are discussed along with future scope and challenges of MoS2as the electrode materials.

Carbon dots (CDs) have received much attention in the field of sensing as fluorescent nanomaterials. They possess simple preparation, excellent optical properties, low toxicity, and brilliant biocompatibility. Photoluminescence in CDs is caused by chemical features, such as graphitic conjugated cores, molecular fluorophores and surface defect states. The emission wavelength of fabricated CDs primarily accumulates single bands in the blue, green or red region. Meanwhile, the structure of CDs and the relationship between their structure and optical properties are still being debated. Apart from that, the existence of single emission bands reduces the efficiency of CDs for sensing multiple analytes in a single process. To overcome this issue, dual conjugated emitters have been designed using carbon dots, quantum dots and metal–organic frameworks. Their fabrication is time-consuming, requires purification and has unequal photostability. It is critical to design and produce nanoprobes with no labeling and intrinsic dual emission. Thus, this review demonstrates the fundamentals to enlighten the PL mechanism for the multi-emissive response in CDs through ultrafast time-resolved and DFT techniques. An attempt is made to provide an in-depth understanding of diversified paths, such as modulation in their interparticle distance, integration of rare-earth metals and metallic to elucidate the duality in their emission spectra. We have provided insights into implementing intrinsic dual emissive CDs in different ratiometric models. Current states, portable challenges, the significance of fabricating CDs with dual emission peaks and their applications are rationally discussed. The main focus of the review is to discuss various methods and parameters to induce different emissions in CDs with single or dual bands rather than the sensing mechanisms. The goal of this review is to describe the theoretical justification for the sensing response of CDs by varying different parameters, such as pH, precursor, etc.

Hydrogen has received significant attention as a promising clean energy alternative to petroleum derivatives. The low-cost production and storage of hydrogen are essential factors in achieving a cost-effective hydrogen economy. The non-toxic nature of its emissions as well as its high energy content, makes this fuel to be more valuable in the future. Hydrogen is currently widely used in various industries and is produced largely by thermochemical, photobiological, photocatalytic and electrochemical processes. Although substantial progress has been made in developing alternative hydrogen generation methods, additional technical advancement and cost reduction are still required for them to be competitive with current large-scale reforming technology. This review describes the developments in producing hydrogen energy using various methods (thermochemical, photobiological, photocatalytic and electrochemical), along with their future aspects for improving clean and sustainable hydrogen production.

In the modern world, miniaturization of electronic devices for various applications is becoming more common. In particular, the development of flexible energy storage devices have received much attention since they have a superior role in the development of newer technologies such as in public wearables, portable electronic devices, and electronic skin proceeds. Considering the high power density, long cycle life, and shelf life as well as outstanding mechanical strength, flexible supercapacitors are one of the integral parts of these new technologies. In the recent past, researchers have developed innumerable nanomaterials to develop supercapacitors. Among these, MoS2has received much attention due to its several physical and chemical properties, which are more favorable for energy storage applications. Their sheet-like structure, high surface-to-volume ratio, ease of synthesis, flexibility, high mechanical strength, and pseudocapacitive storage mechanism make them potential candidates for flexible storage applications similar to graphene. This review provides recent applications and scope of MoS2in flexible supercapacitors in both composite forms with other carbon nanomaterials, metal oxides, and polymers as well as MoS2itself. Also, we will discuss some MoS2-based self-standing devices, which can generate and store energy in a single device.

Cetirizine (CTR) is second-generation piperazine that belongs to the class of antihistamine that helps reduce allergies. The present research reports on the fabrication of CTR-sensitive sensors for electrochemical detection and quantification of CTR. The electrochemical behavior of CTR was studied utilizing a carbon paste-based electrode (CPE) modified with 2D graphene oxide (GO) and cholesterol (CHO). The facile construction of this sensor was achieved by loading the homogenized CHO-GO/CP (cholesterol-graphene oxide nanohybrid-modified carbon paste) matrix into a polytetrafluoroethylene (PTFE) tube. The surface morphology of the developed sensor’s matrix was carried out employing SEM and AFM. The obtained results convey that fabricated CHO-GO/CPE is relatively more CTR sensitive than CPE or step-wise modified electrodes such as CHO/CPE and GO/CPE. The detection limit of CTR at CHO-GO/CPE was determined to be 9.2 nM. Further, the electrochemical impedance spectroscopy investigation (EIS) showed that CHO-GO/CPE offered less resistance to charge transfer than CPE. Additionally, participation of the total number of charges in the CTR electro-oxidation mechanism, the standard reduction potential of CHO-GO/CPE, charge transfer coefficient, and heterogeneous rate constants were estimated using the effect of the electrolyte’s pH and scan rate variation investigation results. Moreover, adding several excipients to the CTR analyte did not affect the overall electrochemical behavior of CTR, thus confirming the anti-interference characteristics of the fabricated sensor. To evaluate the sensor’s efficiency for a real-time application, CTR detection in tablet solutions was investigated, and the results demonstrated remarkable detection with good recovery.

The electrochemical oxidation of captopril has been investigated by cyclic, linear sweep and differential pulse voltammetry in different pH ranges at a gold electrode. Captopril undergoes one electron and one proton change with an adsorption-controlled process. Effects of the anodic peak potential (Ep), anodic peak current (Ipa) and heterogeneous rate constant (k0) have been discussed. The effect of surfactants was also studied. The oxidation peak corresponds to the thiol and a probable mechanism was proposed. According to the linear relationship between the peak current and the captopril concentration, a differential-pulse voltammetric method for the quantitative determination of captopril was developed. The linear response was obtained in the range of 0.033–2.4 μM with a detection limit of 1.97 × 10−8M with good selectivity and sensitivity. Furthermore, the proposed method was applied to the in vitrodetermination of captopril in pharmaceutical samples, spiked human urine and plasma adopting the differential pulse voltammetric technique for clinical research.

The oxidation of L-tryptophan (L-TRP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.20 mol dm-3was studied spectrophotometrically at 298 K. The reaction between DPC and L-tryptophan in alkaline medium exhibits 1:4 stoichiometry (L-tryptophan: DPC). The reaction is of first order in [DPC] and has less than unit order in [L-TRP] and negative fractional order in [periodate] and [alkali]. Intervention of free radicals was observed in the reaction. The oxidation reaction in alkaline medium has been shown to proceed via a DPC- L-tryptophan complex, which decomposes slowly in a rate determining step followed by other fast steps to give the products. The main products were identified by spot test, IR, 1H NMR, 13CNMR and LC-MS spectral studies. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined.

The present work investigates the electrochemical studies of atorvastatin (ATRV) by establishing graphene (GR) and cationic surfactant cetyltrimethylammonium bromide (CTAB) based electrochemical sensor (GR-CTAB/CPE). The morphological study of a modifier was executed utilizing the electronic scanning microscopy (SEM) technique. GR-CTAB/CPE was identified as a supersensitive electrode for the identification of ATRV, as the electrochemical sensor exhibited enhanced electrocatalytic property and increased peak current in pH 4.2 of phosphate buffer solution employing voltammetric approaches like cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The impact of pre-concentration time, supporting electrolyte (pH), scan rate, and concentration was examined. The number of protons and electrons involved in the electro-oxidative mechanism of ATRV was depicted. The ATRV at the developed sensor has a limit of detection of 2.46 ​× ​10−9 ​M. The proposed method was proven effective in determining ATRV concentration in clinical and biological samples. The data obtained from the recovery studies suggests that the GR-CTAB/CPE was selective and highly sensible in identifying ATRV.

A sensitive method has been proposed for electrochemical reduction of tinidazole (TNZ) drugs employing a voltammetric approach. The supporting electrolyte, phosphate buffer solution (PBS) was prepared for different pH levels (3.0–8.0). The method involves a silica gel modified carbon paste electrode (SG/CPE) as an electrochemical sensor which demonstrated exceptional selectivity and sensitivity towards the detection of TNZ. Various parameters like the impact of accumulation time, pH of supporting buffer, scan rate, and concentration on electro-analysis of TNZ were examined. By the pH study, it was evident that the same number of protons and electrons participated in the process and by scan rate studies, we have estimated the heterogeneous rate constant and electron number. The process was irreversible and diffusion controlled. The linearity range was found to be 1.0 ​μM–10.0 ​μM from concentration variation studies. The detection and quantification limit was calculated and the practical applicability of a developed sensor is tested for tablet and urine samples. The reports obtained by studying the different parameters revealed that the electrode has good stability and sensitivity with reproducible results.