Novel two-step process for the fabrication of MnO2 nanostructures on tantalum for enhanced electrochemical H2O2 detection

Abstract

We demonstrate the influence of MnO2 nanostructures on the H2O2 sensing performance. A novel two-step process using hydrothermal synthesis and spray pyrolysis deposition was used to fabricate the MnO2/Ta sensor electrode. First, different MnO2 nanostructures were synthesized by temperature controlled autoclave-hydrothermal processing through the manipulation of Mn concentration. The MnO2 nanoparticles revealed preferentially oriented (101) peak with high intensity. The absorption bands at 760-375 cm−1 confirmed the coupling between Mn-O stretching modes of tetrahedral and octahedral sites. SEM images revealed the formation of horn-like MnO2 nanowires and nanoflakes with good crystallinity. The MnO2 nanoflakes synthesized with 3 at.% Mn exhibit needle like morphology at the edge of nano-architecture, favorable for remarkable electrochemical properties and stability. Next, the MnO2 nanostructures were transferred onto Ta electrode by a novel spray deposition to form a multi-terminal network H2O2 adsorption layer. The 3D nanoflakes like MnO2/Ta electrode revealed a very low detection limit of 0.06 μM towards H2O2, with insignificant responses for interfering compounds. The sensor also displayed good recovery >95% when tested in milk samples.