Micro-recycling of spent Ni-Cd batteries for the obtention of electrocatalytic coatings

A micro-recycling approach was explored to produce catalytic metallic coatings for the hydrogen evolution reaction (HER). For this aim, discarded Ni-Cd batteries were employed as raw material. After dismantling the batteries, the active powder material, containing Cd and Ni compounds, was leached in a solution containing citric acid and hydrogen peroxide. The dissolved metals were electro-deposited on copper plates using a two electrodes cell at the following potentials (mV): -1900, -2000, and -2100 mV. The CdNi coating produced at -2000 mV, contained 92.6 % Cd and 7.4 % Ni. This coating was studied by cyclic voltammetry (CV) and potentiodynamic analysis in two different KOH solutions (0.1 M and 1.0 M). The CV analysis showed that the CdNi electrode was electrochemically stable in a wide operating voltage range (between oxygen evolution reaction and HER). Using an uncompensated resistance correction, the Tafel slopes for HER were obtained. The potentiodynamic analysis revealed that the synthesized CdNi electrode showed a catalytic activity for HER just 25.5 % smaller than the correspondent response of a standard pure Ni electrode. Our results serve as a proof of concept about the application of micro-recycling of spent batteries to produce sustainable electroactive catalytic materials for hydrogen production.

Sub-second striatal dopamine dynamics assessed by simultaneous fast-scan cyclic voltammetry and fluorescence biosensor

Fast-scan cyclic voltammetry (FSCV) is an electrochemical method used to detect dopamine on a subsecond time scale. Recordings using FSCV in freely behaving animals revolutionized the study of behaviors associated with motivation and learning. Despite this advance, FSCV cannot distinguish between catecholamines, which limits its use to brain regions where dopamine is the predominant neurotransmitter. It has also been difficult to detect dopamine in vivo in some striatal subregions with FSCV. Recently, fluorescent biosensors for dopamine were developed, allowing for discrimination between catecholamines. However, the performance of these biosensors relative to FSCV has not been determined. Thus, we compared fluorescent photometry responses of the dopamine biosensor, dLight, with FSCV. We also used dLight photometry to assess changes in tonic and phasic dopamine, which has not been possible with FSCV. Finally, we examined dopamine dynamics during Pavlovian conditioning in striatal subregions, including the dorsolateral striatum where dopamine measurements are challenging with FSCV.

Electrification of a Milstein-type Catalyst for Alcohol Reformation

Novel energy and atom efficiency processes will be keys to develop the sustainable chemical industry of the future. Electrification could play an important role, by allowing to fine-tune energy input and using the ideal redox agent: the electron. Here we demonstrate that a commercially available Milstein ruthenium cata-lyst (1) can be used to promote the electrochemical oxidation of ethanol to ethyl acetate and acetate, thus demonstrating the four electron oxidation under preparative conditions. Cyclic voltammetry and DFT-calculations are used to devise a possible catalytic cycle based on a thermal chemical step generating the key hydride intermediate. Successful electrification of Milstein-type catalysts opens pathway to use alcohols as renewable feedstock for the generation of esters and other key building blocks in organic chemistry, thus contributing to increase energy efficiency in organic redox chemistry.

Structural Characterization, DFT Geometry Optimization, Cyclic Voltammetry and Biological Assay of (Tellurite-pyridine) Mixed Ligandcomplexesof Cd(II)

This research work presents spectral characterizations (IR, 1H NMR and 13C NMR) of anionic tellurito Cd(II) complexes that prepared using cyanopyridine derivatives as a polydentate ligands. Also, X-ray based techniques involving (EDX and XRD) are applied for cadmium complexes to realize elemental composition and average crystallographic coherence. Moreover, the electrochemical studies represented on cyclic voltammetry are determined for Cd)II) in (absence/presence) of ligands to detect the role of complexation in solution measurements. All the previous experimental investigations are supported with molecular modeling of the geometric optimized structures based on density function theory (DFT) for all compounds accompanied by the calculations of different energetic parameters such as EHOMO and ELUMO. Finally, anti-microbial (antibacterial and antifungal), anti-oxidant and Bleomycin dependent DNA damage are screened for all samples to predict the influence of metal complex formation on the biological activity of pyridyl ligands besides their priority.

A graphene-printed paper electrode for determination of H2O2 in municipal wastewater during the COVID-19 pandemic

Graphene prepared through exfoliation process was printed on paper substrate using inkjet-printer and then printed paper electrode was used as an electrochemical sensor for analysis of H2O2 in cyclic voltammetry.

Electro-Oxidation of Amino-Functionalized Multiwalled Carbon Nanotubes

We report the electrochemistry of amino-functionalized multiwalled carbon nanotubes (MWCNTs-NH2) in the pH range from 0.3 to 6.4 using quantitative cyclic voltammetry (CV) and single entity electrochemistry measurements, making comparison...

Rapid Determination of the ‘Legal Highs’ 4-MMC and 4-MEC by Spectroelectrochemistry: Simultaneous Cyclic Voltammetry and In Situ Surface-Enhanced Raman Spectroscopy

The synthetic cathinones mephedrone (4-MMC) and 4-methylethcathinone (4-MEC) are two designer drugs that represent the rise and fall effect of this drug category within the stimulants market and are still available in several countries around the world. As a result, the qualitative and quantitative determination of ‘legal highs’, and their mixtures, are of great interest. This work explores for the first time the spectroelectrochemical response of these substances by coupling cyclic voltammetry (CV) with Raman spectroscopy in a portable instrument. It was found that the stimulants exhibit a voltammetric response on a gold screen-printed electrode while the surface is simultaneously electro-activated to achieve a periodic surface-enhanced Raman spectroscopy (SERS) substrate with high reproducibility. The proposed method enables a rapid and reliable determination in which both substances can be selectively analyzed through the oxidation waves of the molecules and the characteristic bands of the electrochemical SERS (EC-SERS) spectra. The feasibility and applicability of the method were assessed in simulated seized drug samples and spiked synthetic urine. This time-resolved spectroelectrochemical technique provides a cost-effective and user-friendly tool for onsite screening of synthetic stimulants in matrices with low concentration analytes for forensic applications.

Interaction of Mn(II) and Zn(II) with ciprofloxacin antibiotics

The aim of this study is to check the redox behavior of Mn (II) and Zn (II) metals before and after interaction with ciprofloxacin in potassium chloride solution by using cyclic voltammetry, chronoamperomety and chronocoulometry methods. Equimolar solutions of Mn (II) and ciprofloxacin were mixed to a ratio of 1:2 and that of Zn (II) and ciprofloxacin to a 1:1 ratio. The results showed that the redox couple involved in Mn (II) as well as Mn(II)-ciprofloxacin interaction systems are quasi-reversible. However, the Zn (II) systems showed reversibility and the Zn(II)-ciprofloxacin interaction was quasi-reversible. The results obtained from the chronoamperometric study showed that after interaction with ciprofloxacin the rate of electrolysis in the metal systems decreased. Bangladesh J. Sci. Ind. Res.56(4), 285-292, 2021

A Reliable Cyclic Voltammetry Technique for the Degradation of Salicylaldehyde: Electrode Kinetics

Salicylaldehyde (SA) is used in numerous biological, pharmaceutical, and industrial applications. Releasing effluents from these industries contaminates water. So the degradation of salicylaldehyde is necessitated. The electrochemical degradation of salicylaldehyde in buffered media was studied using the eco-friendly cyclic voltammetry (CV) technique on a platinum electrode at different scan rates. Kinetic and electrochemical parameters were evaluated for the reaction such as standard heterogeneous rate constant (k0,2.468×103 s-1 ), anodic electron transfer rate constant (kox,2.507×103 s-1), electron transfer coefficient of reaction (?,0.673), and formal potential (E0, 1.0937) under the influence of scan rate. The nature of the reaction is found to be diffusion controlled. The concentration study in the range of 1 mM to 4 mM was calibrated. The limit of detection and the limit of quantification were calculated to be 0.0031 mM and 0.0103 mM respectively.