Application of manganese (II) phthalocyanine synthesized in situ in the SiO2/SnO2 mixed oxide matrix for determination of dissolved oxygen by electrochemical techniques

Research on the Influence of Core Sensing Components on the Performance of Galvanic Dissolved Oxygen Sensors

The galvanic dissolved oxygen sensor finds widespread applications in multiple critical fields due to its high precision and excellent stability. As its core sensing components, the oxygen-permeable membrane, electrode, and electrolyte significantly impact the sensor's performance. To systematically investigate the comprehensive effects of these core sensing components on the performance of galvanic dissolved oxygen sensors, this study selected six types of oxygen-permeable membranes made from two materials (Perfluoroalkoxy Polymer (PFA) and Fluorinated Ethylene Propylene Copolymer (FEP)) with three thicknesses (0.015 mm, 0.03 mm, and 0.05 mm). Additionally, five concentrations of KCl electrolyte were configured, and four different proportions of lead-tin alloy electrodes were chosen. Single-factor and crossover experiments were conducted using the OxyGuard dissolved oxygen sensor as the experimental platform. The experimental results indicate that under the same membrane thickness conditions, PFA membranes provide a higher output voltage compared to FEP membranes. Moreover, the oxygen permeability of FEP membranes is more significantly affected by temperature. Furthermore, the oxygen permeability of the membrane is inversely proportional to its thickness; the thinner the membrane, the better the oxygen permeability, resulting in a corresponding increase in sensor output voltage. When the membrane thickness is reduced from 0.05 mm to 0.015 mm, the sensor output voltage for PFA and FEP membranes increases by 86% and 74.91%, respectively. However, this study also observed that excessively thin membranes might compromise measurement accuracy. In a saturated, dissolved oxygen environment, the sensor output voltage corresponding to the six oxygen-permeable membranes used in the experiment exhibits a highly linear inverse relationship with temperature (correlation coefficient ≥ 98%). Meanwhile, the lead-tin ratio of the electrode and electrolyte concentration have a relatively minor impact on the sensor output voltage, demonstrating good stability at different temperatures (coefficient of variation ≤ 0.78%). In terms of response time, it is directly proportional to the thickness of the oxygen-permeable membrane, especially for PFA membranes. When the thickness increases from 0.015 mm to 0.05 mm, the response time extends by up to 2033.33%. In contrast, the electrode material and electrolyte concentration have a less significant effect on response time. To further validate the practical value of the experimental results, the best-performing combination of core sensing components from the experiments was selected to construct a new dissolved oxygen sensor. A performance comparison test was conducted between this new sensor and the OxyGuard dissolved oxygen sensor. The results showed that both sensors had the same response time (49 s). However, in an anaerobic environment, the OxyGuard sensor demonstrated slightly higher accuracy by 2.44%. This study not only provides a deep analysis of the combined effects of oxygen-permeable membranes, electrodes, and electrolytes on the performance of galvanic dissolved oxygen sensors but also offers scientific evidence and practical guidance for optimizing sensor design.

Oxygen sensitive 1-amino-2-naphthol immobilized functionalized-carbon nanotube electrode

Immobilization of 1-amino-2napthol (AN) is enhanced complexing with Cu²⁺ on multiwalled carbon nanotubes (f-MWCNT) surface. Oxygen is reduced at the ligand (AN) site into water, therefore AN–Cu²⁺ immobilized on MWCNT exhibits oxygen sensing.

Review of Dissolved Oxygen Detection Technology: From Laboratory Analysis to Online Intelligent Detection

Dissolved oxygen is an important index to evaluate water quality, and its concentration is of great significance in industrial production, environmental monitoring, aquaculture, food production, and other fields. As its change is a continuous dynamic process, the dissolved oxygen concentration needs to be accurately measured in real time. In this paper, the principles, main applications, advantages, and disadvantages of iodometric titration, electrochemical detection, and optical detection, which are commonly used dissolved oxygen detection methods, are systematically analyzed and summarized. The detection mechanisms and materials of electrochemical and optical detection methods are examined and reviewed. Because external environmental factors readily cause interferences in dissolved oxygen detection, the traditional detection methods cannot adequately meet the accuracy, real-time, stability, and other measurement requirements; thus, it is urgent to use intelligent methods to make up for these deficiencies. This paper studies the application of intelligent technology in intelligent signal transfer processing, digital signal processing, and the real-time dynamic adaptive compensation and correction of dissolved oxygen sensors. The combined application of optical detection technology, new fluorescence-sensitive materials, and intelligent technology is the focus of future research on dissolved oxygen sensors.

Nonenzymatic amperometric dopamine sensor based on a carbon ceramic electrode of type SiO2/C modified with Co3O4 nanoparticles

An amperometric nonenzymatic dopamine sensor has been developed. Cobalt oxide (Co₃O₄) nanoparticles were uniformly dispersed inside mesoporous SiO₂/C. A sol-gel process was used for the preparation of this mesoporous composite material (SiO₂/C). This mesoporous composite has a pore size of around 13-14 nm, a large surface area (S_BET 421 m²·g^-1) and large pore volume (0.98 cm³·g^-1) as determined by the BET technique. The material compactness was confirmed by SEM images which showing that there is no phase segregation at the magnification applied. The chemical homogeneity of the materials was confirmed by EDX mapping. The SiO₂/C/Co₃O₄ nanomaterial was pressed in desk format to fabricate a working electrode for nonenzymatic amperometric sensing of dopamine at a pH value of 7.0 and at a typical working potential of 0.25 V vs SCE. The detection limit, linear response range and sensitivity are 0.018 μmol L^-1, 10-240 μmol L^-1, and 80 μA·μmol L^-1 cm^-2, respectively. The response timé of the electrode is less than 1 s in the presence of 60 μmol L^-1 of dopamine. The sensor showed chemically stability, high sensitivity and is not interfered by other electroactive molecules present in blood. The repeatability of this sensor was evaluated as 1.9% (RSD; for n = 10 at a 40 μmol L^-1 dopamine level. Graphical abstract Schematic presentation of the preparation of a nanostructured composite of type SiO₂/C/Co₃O₄ for electrooxidative sensing of dopamine.

Immobilization of alkynyl functionalized manganese phthalocyanine via click electrochemistry for electrocatalytic oxygen evolution reaction

Modified electrodes (ITO/PANI-N₃-MnPc and GCE/PANI-N₃-MnPc) were constructed by click electrochemistry (CEC). The GCE/PANI-N₃-MnPc electrode was tested as a potential electrocatalyst for water splitting reaction.

Study on the structural and electrocatalytic properties of Ba2+- and Eu3+-doped silica xerogels as sensory platforms

This work reports on the sol–gel synthesis of barium- and europium-doped silica xerogel and its use as an electrocatalytic sensor.