Hybrid 2D-1D nanostructure of NiO composited with PEDOT:PSS and rGO: Bifunctional electrocatalyst towards methanol oxidation and oxygen evolution reaction

The electrocatalytic performance and stability of methanol oxidation reaction (MOR) and oxygen evolution reaction (OER) are mainly governed by the interfacial and surface characteristics of catalysts. Herein, a ternary nanocomposite (NiPR) of reduced graphene oxide (rGO), poly (3,4-ethylenedioxythiophene) (PEDOT): poly (styrene sulfonic acid) (PSS) and nickel oxide (NiO) nanoplate-nanorod structures has been developed to use as electrooxidation catalyst for methanol and water. Two-dimensional nanostructures have large number of electroactive sites at the surface and conjugation with one-dimensional nanostructure provides additional active sites at the interface. The synergetic effect of conducting polymer of PEDOT:PSS, large surface area of rGO and metal oxide enhances electrical conductivity and also facilitates contact between electrolyte ions and the nanocomposite for methanol and water oxidations. The linear rise in current has been observed with increase in methanol within the concentration range from 0.1 to 2 M. The electrocatalytic activity of the ternary electrocatalyst has been analysed by cyclic voltammetry in 0.5 M methanol containing 0.5 M NaOH at various sweep rates (10-150 mV s(-1)). An anodic current density of 62.6 mA cm(-2) has been obtained with an onset voltage of 0.34 V at a 50 mV s(-1). sweep rate for 0.5 M of methanol oxidation. Moreover, NiPR nanocomposite shows a lower overvoltage of 439 mV vs RHE at 20 mA cm(-2) with a small Tafel slope of 65 mV dec and long-term stability (similar to 7 hours) in 0.5 M NaOH for OER.