Advancing OER and Methanol Oxidation: A Comparative Study of Silver and Copper Modified Hydrothermally Synthesized Nickel Cobalt Oxide Electrocatalyst

Abstract

Finding an alternative energy source that is more reliable and less harmful to the environment has been one of the scientific research priorities for the past few decades. In this pursuit electrocatalysis has proven to be the best choice to move forward with. This thesis presents a comprehensive study leveraging hydrothermally synthesized NiCo2O4 and uniquely extracted silver and copper metal from their salts. The extraction method results in the production of silver metal and copper/copper oxide mixture, which when used to modify the surface of NiCo2O4 through ultrasonication, enhances its electrocatalytic performance not just for Oxygen Evolution Reaction (OER) but also for Methanol Oxidation Reaction (MOR). Moreover, the synthesized electrocatalysts are characterized using X-Ray Diffraction analysis (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). In the modified electrocatalysts both the metals influence the electrochemical properties of the support NiCo2O4 in their own way, which draws a parallel between two transition metals and gives us the opportunity to meticulously tune the electrocatalyst by understanding their behavior. The Cu/Cu2O@NiCo2O4 5% gives the lowest onset potential of 360 mV at 10 mAcm-2 . On the other hand, Ag@NiCo2O4 4% gives an exceptionally high output current of 390.88 mAcm-2 at 1.79 V vs RHE for OER. For MOR both electrocatalysts have comparable onset potential, however, Cu/Cu2O@NiCo2O4 shows peak current density of 120 mAcm-2 at just 0.54 vs Ag/AgCl.