In situ or Ex situ Synthesis for Electrochemical Detection of Hydrogen Peroxide-An Evaluation of Co2SnO4/RGO Nanohybrids

Abstract

Nowadays, there is no doubt about the high electrocatalytic efficiency that is obtained when using hybrid materials between carbonaceous nanomaterials and transition metal oxides. However, the method to prepare them may involve differences in the observed analytical responses, making it necessary to evaluate them for each new material. The goal of this work was to obtain for the first time Co₂SnO₄ (CSO)/RGO nanohybrids via in situ and ex situ methods and to evaluate their performance in the amperometric detection of hydrogen peroxide. The electroanalytical response was evaluated in NaOH pH 12 solution using detection potentials of -0.400 V or 0.300 V for the reduction or oxidation of H₂O₂. The results show that for CSO there were no differences between the nanohybrids either by oxidation or by reduction, unlike what we previously observed with cobalt titanate hybrids, in which the in situ nanohybrid clearly had the best performance. On the other hand, no influence in the study of interferents and more stable signals were obtained when the reduction mode was used. In conclusion, for detecting hydrogen peroxide, any of the nanohybrids studied, i.e., in situ or ex situ, are suitable to be used, and more efficiency is obtained using the reduction mode.

Keywords: Co2SnO4; electrochemical detection; nanohybrids; reduced graphene oxide.

Figure 1

(a) Phase analysis of XRD patterns [ICDD #00-029-0514]. (b) Raman spectra between 1000 and 3000 cm⁻¹ Raman shift. (c) Raman spectra between 200 and 750 cm⁻¹ Raman shift. (d) N₂ adsorption–desorption isotherm profile.

Figure 2

SEM micrographs of (a) CSO+RGO and (b) CSO/RGO. EDX mapping (oxygen, tin, and cobalt) of (c) CSO+RGO and (d) CSO/RGO.

Figure 3

Nyquist plot of 10 mM hydrogen peroxide solution as a redox probe on: a. CSO/RGO, b. CSO+RGO, c. RGO, d. CSO. Figure Inset: Total resistance and equivalent circuit.

Figure 4

(a) Amperometric response of A. CSO+RGO, B. CSO/RGO, C. RGO and D. CSO at −0.400 V; (b) sensitivity toward H₂O₂ reduction obtained from amperometric experiments; (c) calibration plot for the electrochemical H₂O₂ reduction response. (d) Amperometric response of A. CSO+RGO, B. CSO/RGO, C. RGO, and D. CSO at 0.300 V. (e) Sensitivity toward H₂O₂ oxidation obtained from amperometric experiments. (f) Calibration plot for the electrochemical H₂O₂ oxidation response. Amperometric experiments were performed with the successive addition of 0.1 mM H₂O₂ in NaOH solutions at pH 12.

Figure 5

Amperometric responses to successive additions of 0.1 mM and 1.0 mM H₂O₂, uric acid (AU), glucose (GLU), sodium sulfate (SO₄²⁻) and ascorbic acid (AA): (a) reduction for CSO/RGO in situ and (b) reduction for CSO+RGO ex situ electrodes at −0.400 V applied, (c) oxidation for CSO+RGO ex situ (d) oxidation for CSO/RGO in situ electrodes at 0.300 V applied.