Mingled MnO₂ and Co₃O₄ Binary Nanostructures on Well-Aligned Electrospun Carbon Nanofibers for Nonenzymatic Glucose Oxidation and Sensing

Abstract

This work reports on uniformly mingled nanostructures of Co3O4 and MnO2 deposited on a well-aligned electrospun carbon nanofiber (WA-ECNF) mat for rapid glucose electrooxidation and sensing. The hybridization of Co3O4 and MnO2 is synthesized by a simple one-step and template-free electrodeposition technique with a constant low current at 60 μA for 3 h at room temperature in an aqueous solution. The binary MnO2/Co3O4@WA-ECNF nanomatrix electrode exhibits excellent uniformity with high porosity, increased electrochemically active surface areas and conductivity, fast charge transfer, and improved efficiency for glucose electrooxidation in comparison to the monometallic MnO2 or Co3O4 at the WA-ECNFs. The electrochemical performance of the MnO2/Co3O4@ECNF electrode is characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). The MnO2/Co3O4@ECNF electrode shows superior sensing characteristics including a rapid glucose oxidation response within 5 s, a wide range of detection from 5 μM to 10.9 mM, an excellent sensitivity of 1159 μA mM–1 cm–2, and a detection limit of 0.3 μM (S/N = 3) with satisfactory selectivity, great reproducibility, and stability. These results are discussed with mechanisms of glucose absorption to the nanostructure surfaces followed by a fast glucose oxidation reaction.

Electrospun Manganese-Based Metal–Organic Frameworks for MnOx Nanostructures Embedded in Carbon Nanofibers as a High-Performance Nonenzymatic Glucose Sensor

“…In the second linear range of 4.1−9.1 mM, MOF MnO x -CNFs provide an optimal environment to allow efficient adsorption of glucose molecules and desorption of reaction byproducts. 53 In particular, the sensing characteristics of the MOF MnO x -CNFs/GCE electrode are among the best-reported values for nonenzymatic sensors based on nanostructured materials (Table 1). 54−60 The outstanding catalytic activity of MOF MnO x -CNFs in glucose oxidation can be attributed to the following factors.…”

“…The first linear fit implies that the electro-oxidation of the glucose reaction is limited by glucose absorption onto electrochemically active sites, which is followed by redox reaction and charge transfer. In the second linear range of 4.1–9.1 mM, MOF MnO x -CNFs provide an optimal environment to allow efficient adsorption of glucose molecules and desorption of reaction byproducts . In particular, the sensing characteristics of the MOF MnO x -CNFs/GCE electrode are among the best-reported values for nonenzymatic sensors based on nanostructured materials (Table ).…”

Binary MnO2/Co3O4Metal Oxides Wrapped on Superaligned Electrospun Carbon Nanofibers as Binder Free Supercapacitor Electrodes

“…It is known that metal doping can effectively increase the number of micro- and mesopores in the nanomaterials . Mingled binary MnO 2 /Co 3 O 4 structures stabilize the fine porous structure for better electrochemical performance . An increase in the number of micro- and mesopores in the nanomaterial can effectively enhance the specific surface area, hence increasing the specific capacitance by divulging more active sites .…”

“…21 Mingled binary MnO 2 /Co 3 O 4 structures stabilize the fine porous structure for better electrochemical performance. 66 An increase in the number of micro-and mesopores in the nanomaterial can effectively enhance the specific surface area, hence increasing the specific capacitance by divulging more active sites. 67 Moreover, the affinity of water to the binary metal oxide porous surface, which is revealed in the XPS deconvolution graph of O 1s (Figure 4c), can facilitate the electrolyte transportation inside the electrode's active material, thus improving its performance by increasing its ionic conductivity and decreasing its polarization.…”

A Perspective on the Recent Amelioration of Co3O4 and MnO2 Bifunctional Catalysts for Oxygen Electrode Reactions

“…An inherent property, surface area is often morphology dependent since different morphologies have different surface areas even for identical phases [25]. The electrochemical reaction takes place only at the interface, where surface atoms are in contact with electrolytes rather than interior atoms.…”