pH sensing in aqueous solutions using a MnO2 thin film electrodeposited on a glassy carbon electrode

Abstract

An electrodeposition method based on chronoamperometry was used to develop a highly reproducible and fast elaboration method of adherent manganese dioxide thin films on a glassy carbon electrode from aqueous solutions containing sulfuric acid and manganese sulfate. The resulting films were found to have a nanostructured character presumably due rather to birnessite (G-MnO 2) than to J-MnO 2 , as suggested by their Raman and XRD signatures. They lead to modified electrodes that present an obvious although complex pH dependent potentiometric response. This sensor indeed showed a single slope non-Nernstian linear behaviour over the 1.5-12 pH range for increasing pH direction ("trace") whereas a Nernstian two slopes linear behaviour was observed for decreasing pH direction ("re-trace"). Preliminary EIS experiments carried out at a pH value of 1.8 seem to reveal a sensitivity mechanism based on proton insertion process at least at highly acidic pH values.

Electrocatalytic Oxygen Reduction and Oxygen Evolution in Mg‐Free and Mg–Containing Ionic Liquid 1‐Butyl‐1‐Methylpyrrolidinium Bis (Trifluoromethanesulfonyl) Imide

“…Supporting Information). MnO 2 was electrodeposited on the GC substrate according to the procedure described by Cherchour et al [46] First the pH of an aqueous solution of manganese (II) sulfate was adjusted to 1.8 using sulfuric acid. Then, electrodeposition was performed by stepping the potential step from 0.4 to 1.1 V vs SCE for 30 s. The composition and structure of the electrodeposited film was then characterized by SEM, XPS and Raman spectroscopy (cf.…”

“…Supporting Information). MnO 2 was electrodeposited on the GC substrate according to the procedure described by Cherchour et al . First the pH of an aqueous solution of manganese (II) sulfate was adjusted to 1.8 using sulfuric acid.…”

New Developments in Smart Bandage Technologies for Wound Diagnostics

“…In most cases, a functional material containing pH sensitive components is applied to the surface of an appropriate sensor substrate through a variety of methods that include: Adsorption/monolayer, [ 39,48 ] polymer fi lms, [ 36 ] screen printed inks, [ 35,38,40,47 ] covalent attachment, [ 46,47 ] or electrodeposition. [ 32,33,37,[42][43][44]50 ] Screen printed electrochemical sensors have been designed specifi cally for wound pH monitoring applications and shown to be a versatile addition. [ 16 ] Rather than relying on potentiometric detection methodologies, they have exploited voltammetric scanning (typically using square-wave voltammetry) in which an endogenous biomarker such as uric acid (which is ubiquitous within most fl uids) is oxidized.…”

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

“…For example, Ni(OH) 2 is most commonly prepared galvanostatically or potentiostatically from an aqueous solution containing nickel nitrate. [159][160][161][162][163][164] Under such circumstances the deposition chemistry involves the direct or indirect reduction of the nitrate ion to either nitrous acid, hydroxylamine or the nitrite ion. 160,171,172 In all cases the hydroxyl ion is generated, resulting in the formation of either a-Ni(OH) 2 or b-Ni(OH) 2 according to eqn (2),…”