Amperometric hydrogen peroxide sensor based on the use of CoFe2O4 hollow nanostructures

Hybrid Layer‐by‐Layer Film of Polyelectrolytes‐Embedded Catalytic CoFe2O4 Nanocrystals as Sensing Units in Capacitive Electrolyte‐Insulator‐Semiconductor Devices

“…One could observe that the lifetime of the EIS sensor was linked to the amount of times, which the device was mounted in and out, respectively, into the electrochemical cell, and not due to the amount of measurements performed by the sensor and/or by the film degradation in the chip surface. Furthermore, the performance of the 3‐bilayer EIS‐CoFe 2 O 4 sensor, in terms of linear detection concentration range, fits to data discussed in literature for amperometric H 2 O 2 sensors based on the CoFe 2 O 4 material . For instance, Vasuki et al reported the use of CoFe 2 O 4 hollow nanostructures in the concentration range from 10 × 10 –6 m to 1.2 × 10 –3 m .…”

“…Furthermore, the performance of the 3‐bilayer EIS‐CoFe 2 O 4 sensor, in terms of linear detection concentration range, fits to data discussed in literature for amperometric H 2 O 2 sensors based on the CoFe 2 O 4 material . For instance, Vasuki et al reported the use of CoFe 2 O 4 hollow nanostructures in the concentration range from 10 × 10 –6 m to 1.2 × 10 –3 m . In other reports, CoFe 2 O 4 nanoparticles decorated with graphene oxide presented a linear calibration curve in the concentration range of 0.9 × 10 –6 m to 0.9 × 10 –3 m while a CoFe 2 O 4 ‐chitosan nanocomposite system reported a linear range of detection from 30 × 10 –6 m to 8 × 10 –3 m .…”

“…Nevertheless, a possible overall mechanism that can explain the operating principle of the EIS‐CoFe 2 O 4 sensor may be assigned to the catalytic activity of the CoFe 2 O 4 nanocrystals toward H 2 O 2 . Vasuki et al and Zhu et al reported that for CoFe 2 O 4 spinel materials the H 2 O 2 is attracted by the Co 2+ , and the CoFe 2 O 4 weakens the O‐H bonds of H 2 O 2 , causing its decomposition and releasing H + ‐ions that is responsible to promote the interface potential across the solid‐liquid junction (chip sensor‐H 2 O 2 solution), which finally generates the response signal of the EIS sensor. In this process the H 2 O 2 oxidizes the Co 2+ to Co 3+ and after the reduction to Co 2+ the adsorbed H 2 O 2 is decomposed, releasing the O 2 molecule and H + ‐ions (see Figure for the chemical reaction involved toward H 2 O 2 detection using the EIS‐CoFe 2 O 4 sensor).…”

“…Concerning the potential use of different nanomaterials with suitable properties for sensing applications, cobalt ferrite (CoFe 2 O 4 ) nanocrystals are an interesting material for application in catalysis and sensor fields due to their ability to catalyze the breakdown of some dangerous substances such as cyclohexane, alkenes, and hydrogen peroxide . Particularly for the latter, it is reported that compound‐based MFe 2 O 4 (transition metal) presents propitious properties for H 2 O 2 determination due to its spinel structures, as M x+ ions may interact with the O–O bond of H 2 O 2 , releasing ions and electrons that can be measured by using different electrochemical methods . In this sense, the capacitive EIS sensor can be an alternative sensing platform toward H 2 O 2 detection, as the release of H + ‐ions in solution can promote an interface potential across the solid–liquid junction (sensor chip–H 2 O 2 solution), which can be detected by the EIS sensor .…”

“…However, to our knowledge there are no studies reported involving EIS sensors using CoFe 2 O 4 as sensitive layer for H 2 O 2 detection. Most of the studies reporting the application of CoFe 2 O 4 toward this compound are based on amperometric sensors …”