Promising Electrocatalytic Water and Methanol Oxidation Reaction Activity by Nickel Doped Hematite/Surface Oxidized Carbon Nanotubes Composite Structures

Abstract

Tailoring the precise construction of non-precious metals and carbon-based heterogeneous catalysts for electrochemical oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) is crucial for energy conversion applications. Herein, this work reports the composite of Ni doped Fe₂ O₃ (Ni-Fe₂ O₃ ) with mildly oxidized multi-walled CNT (O-CNT) as an outstanding Mott-Schottky catalyst for OER and MOR. O-CNT acts as a co-catalyst which effectively regulates the charge transfer in Ni-Fe₂ O₃ and thus enhances the electrocatalytic performance. Ni-Fe₂ O₃ /O-CNT exhibits a low onset potential of 260 mV and overpotential 310 mV @ 10 mA cm^-2 for oxygen evolution. Being a Mott-Schottky catalyst, it achieves the higher flat band potential of -1.15 V with the carrier density of 0.173×10²⁴ cm^-3 . Further, in presence of 1 M CH₃ OH, it delivers the MOR current density of 10 mA cm^-2 at 1.46 V vs. RHE. The excellent electrocatalytic OER and MOR activity of Ni-Fe₂ O₃ /O-CNT could be attributed to the synergistic interaction between Ni-doped Fe₂ O₃ and O-CNT.

Keywords: Mott-Schottky catalysts; carbon nanotubes; electrochemistry; methanol oxidation reaction; oxygen evolution reaction.