Direct electrochemistry of catalase at multiwalled carbon nanotubes-nafion in presence of needle shaped DDAB for H2O2 sensor

The direct electrochemistry of catalase (CAT) at didodecyldimethylammonium bromide (DDAB) present on nafion dispersed multiwalled carbon nanotubes (MWCNTs-NF) modified glassy carbon electrode (GCE) has been reported. The presence of DDAB in MWCNTs-NF-CAT film enhances the surface coverage concentration of CAT (FeIII/II) to 48%. Similarly, in presence of DDAB, there is a 57% enhancement in electron transfer rate (ks) with 66% increase in CAT stability. (FeIII/II) redox couple exhibits linear dependence with the pH variation (−51 mV pH−1). The UV–vis absorption spectroscopy study reveals the entrapped CAT in DDAB film retains its native structure at MWCNTs-NF modified electrodes. Similarly, electrochemical impedance spectroscopy results confirm the co-existence of CAT and DDAB in the modified film. Further, scanning electron microscopy results reveal the structural morphological difference between various components in MWCNTs-NF-(DDAB/CAT) film. The cyclic voltammetry (CV) and amperometry (i–t curve) have been used for the measurement of electroanalytical properties of H2O2 by means of various film modified GCEs. The sensitivity values of MWCNTs-NF-(DDAB/CAT) film for H2O2 using CV (35.62 μA mM−1 cm2) are higher than the values which are obtained for MWCNTs-NF-CAT film (2.74 μA mM−1 cm2). Similarly, the sensitivity values using i–t curve are 101.74 μA mM−1 cm2 for MWCNTs-NF-(DDAB/CAT) and 74.69 μA mM−1 cm2 for MWCNTs-NF-CAT film. Finally, the diffusion coefficient of H2O2 at MWCNTs-NF-(DDAB/CAT) film (3.4 × 10−10 cm2 s−1) has been calculated using rotating disc electrode studies.