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.