Here in, we are reporting simple, selective and direct immobilization of a biological redox mediator, catechol (1,2-dihydroxy phenol, CA), on glassy carbon electrode (GCE) and screen-printed carbon electrode (SPCE) surfaces through electrochemical oxidation procedures in aqueous solutions without any other external matrix. The CA immobilized activated carbon electrodes (GCE*-CAads and SPCE*-CAads) have shown well-defined and stable surface confined redox behavior centered (Eo′) at ∼0.05 V vs Ag/AgCl and peak-to-peak separation (ΔEp) of ∼20 mV in pH 7 PBS. This observation is selective for CA on the carbon surfaces. Control experiments with other hydroxyl phenols including, Dopamine and Resorcinol failed to show any such adsorption or immobilization on the carbon surfaces. XPS and ATIR/FTIR characterization implies covalent immobilization of the C-4 of the CA through carboxylic functional group of the activated surfaces. Crown Copyright © 2009.

Senthil Kumar Annamalai

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Gayathri P

Department of Database Systems

School of Computer Science and Engineering

Sornambikai S

Zen J.-M.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Journal of Electroanalytical Chemistry

Electrocatalytic oxidation of NADH has been demonstrated using an electrochemically immobilized Alizarin (AZ) on multiwalled carbon nanotube (MWCNT) modified glassy carbon electrode (GCE/AZ@MWCNT) in pH 7 phosphate buffer solution. The GCE/AZ@MWCNT shows three surface-confined redox peaks centered (E1/2) at -0.067, -0.351 and -0.620 V vs Ag/AgCl, due to the 1,2 dihydroxy and anthraquinone (at two different energetic MWCNT) redox sites of the AZ. Calculated respective surface excess values are 59.13, 8.12 and 9.73×10-10 mol.cm-2. Amongst the three, the E 1/2 = -0.067 redox peak shows specific NADH electrocatalytic oxidation behavior in a concentration range = 0-7 mM by cyclic voltammetry. Transmission electron microscope characterization reveals immobilization of the AZ both on inner and outer walls of the MWCNT. Investigation on different CNTs viz., impure, purified, functionalized MWCNT, and single-walled carbon nanotube systems, the impure MWCNT shows the highest AZ immobilization and electrocatalytic behavior towards NADH oxidation. ©The Electrochemical Society.

ECS Transactions

Electrocatalytic Oxidation of NADH Using Alizarin Immobilized Carbon Nanotube Modified Electrode

Search for simple and economical electrocatalyst for the hydrogen gas evolution reaction (HER), which can resemble to the performance of Pt and other precious metals, is a challenging research interest. In this work, a systematic effect of pre-treatment potential of screen-printed carbon (SPCE) surface on the HER performance in 0.5 M H 2 SO 4 was carried out. A new observation of a low potential HER (onset potential, E onset = −0.02 V vs. RHE) at a cathodic potential, −0.5 V vs. Ag/AgCl on 1 hr pre-treated screen-printed carbon electrode (SPCE*, * = pre-treated) was observed. Physicochemical and electrochemical characterizations of the SPCE* by field emission scanning electron-microscope, Raman, IR and X-Ray photoelectron spectroscopes reveals specific generation of carboxylic acid functionalized carbon surface and in turn for the enhanced HER on the modified electrode surface. Electrochemical characterization of SPCE* with Fe(CN) 6 3− support the observation. A marked decrement in the peak current and significant increase in the peak-to-peak separation potential response due electrostatic repulsion between the anion sites of Fe(CN) 6 3− and –COO – were noticed. This observation is in parallel with the reduced electrical double layer capacitance value of the SPCE* system. The E onset and Tafel value (54.7 mV dec −1 ) obtained here are comparable to those at Pt, MoS 2 , MoSe 2 and superior over the N- and P-doped graphene/carbon electrocatalysts for HER. A prototype HER system was developed and demonstrated for H 2 gas production at a rate of 0.0053 μM s −1 (Operating potential = −0.5 V vs Ag/AgCl), which is comparable to that of precious metal and metal compound electrocatalysts based HER performance. © 2019 Elsevier B.V.

A catholically pre-treated low cost screen-printed carbon electrode surface for metal compounds electrocatalyst like hydrogen evolution activity

Simple, selective and contentious fluidic detection of As(iii) species in drinking water has been demonstrated.

Analytical Methods

Flow-injection analysis coupled with electrochemical detection of poisonous inorganic arsenic(iii) species using a gold nanoparticle/carbon nanofiber/chitosan chemically modified carbon screen printed electrode in neutral pH solution

Amongst various isomers of dihydroxy benzene, 1,2-dihydroxy benzene (Catechol, CA) isomer and its derivative based natural compounds are considered to be the key functional group for various health benefits. In electrochemistry, pulse voltammetric techniques combined with chemically modified electrodes (CMEs) have been often reported for simultaneous detection of 1,2- (CA); 1,3- (Resorcinol, RE) and 1,4-dihydroxy benzene (hydroquinone, HQ) isomers at discreet potentials, ∼0.1, ∼0.2 and ∼0.4 V vs Ag/AgCl, respectively, in a neutral pH condition. Indeed, the above technique and the reported CMEs were not suitable for selective amperometric i-t based detection of CA without interference from HQ and RE. In fact, at CA detection potential, ∼0.2 V, HQ also got co-detected. Herein, we report a palladium nanoparticles-Chitosan indium tin oxide modified electrode (ITO/CHIT@Pdnano) as a selective amperometric sensor system for CA isomer detection without any interference of HQ and RE. A specific interaction between Pd2+ and CA as {Pd2+-CA complex} is proposed as a key factor for the selectivity achieved in this work. As a proof of concept, flow injection analysis of CA functional group in wine and tea real samples was demonstrated. © 2017 Elsevier B.V.

Sensors and Actuators B: Chemical

Selective amperometric and flow injection analysis of 1,2-dihydroxy benzene isomer in presence of 1,3- and 1,4-dihydroxy benzene isomers using palladium nanoparticles-chitosan modified ITO electrode

Electrochemical oxidation of aniline and its derivatives, such as aminobenzene sulfonic acid (SA), on solid electrodes [Pt, glassy carbon (GCE), indium tin oxide (ITO), and Au] leads to the formation of conducting polyaniline (PANI) and its derivatives as the only products in aqueous solution. We report here, for the first time, the unique and unexpected electrochemical transformation of ortho-, meta- and para-SA into highly redox-active, adsorption-controlled quinone isomers [catechol (CA), resorcinol (Re), hydroquinone (HQ)], without any PANI-like product formation on a multiwalled carbon nanotube (MWCNT)-modified GCE (GCE/MWCNT@Q, where Q=quinone) within a restricted potential cycling window (−0.4 to 0.4 V versus Ag/AgCl) in a neutral pH solution. It is proposed that upon the potential cycling of a 2.1 wt% iron-impurity-containing MWCNT-modified GCE with a millimolar concentration of SA isomers, benzene (after deamination and desulfonation of SA) and hydrogen peroxide (from the oxygen reduction reaction at −0.4 V vs. Ag/AgCl) are formed as intermediate species, which are then converted to quinones and quinone-like products through the electro-Fenton reaction (utilizing the iron impurity and H2O2). One of the reaction intermediates, benzene, was identified (Mw=77.8±0.5 g mol−1) by using an in situ electrochemical quartz crystal microbalance coupled cyclic voltammetric technique. By using GCE/MWCNT@HQ as a model system, efficient electrocatalytic oxidation and sensing of the reduced form of nicotinamide adenine dinucleotide (NADH) was successfully demonstrated. © 2017 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim

ChemElectroChem

Unexpected Electrochemical Transformation of Aminobenzene Sulfonic Acid Isomers to Respective Surface-Confined-Redox Active Quinones Bypassing Polyaniline on a MWCNT Surface

Screen-printed enzymatic biosensor modified with carbon nanotube for the methimazole determination in pharmaceuticals formulations

The Journal of Physical Chemistry C

Electrochemical Functionalization of a Gold Electrode with Redox-Active Self-Assembled Monolayer for Electroanalytical Application

Journal of Solid State Chemistry

Oxidation and deprotonation of synthetic FeII–FeIII (oxy)hydroxycarbonate Green Rust: An X-ray photoelectron study

Talanta

Amperometric and voltammetric detection of hydrazine using glassy carbon electrodes modified with carbon nanotubes and catechol derivatives

Free Radical Biology and Medicine

Evidence from ESI-MS for NQO1-catalyzed reduction of estrogen ortho-quinones

Selective covalent immobilization of catechol on activated carbon electrodes

Journal	Data powered by TypesetJournal of Electroanalytical Chemistry
Publisher	Data powered by TypesetElsevier BV
ISSN	1572-6657
Open Access	0