Mg- and Ni-modified Fe2O3@rGO as enhanced peroxide scavenger cocatalysts in oxygen reduction reaction

Abstract

The exploitation of graphene oxide (GO)-based composites for fuel cell electrocatalysts has gained significant interest, yet the integration of iron oxide nanoparticles grafted onto GO, doped with different metals, remains relatively unexplored. This study aims to fill this gap by synthesizing and characterizing Fe₂O₃ nanoparticles grafted on GO doped with two different metals, specifically magnesium and nickel, each at three different concentrations (6%, 12%, and 18% by weight). The successful doping and incorporation of Fe₂O₃ on the GO matrix is confirmed using X-ray diffraction (XRD) and Raman spectroscopy. Scanning electron microscopy (SEM) provides insights into the morphology and dispersion of Fe₂O₃ nanoparticles on the GO surface. Rotating Ring Disk Electrode (RRDE) is used to analyze the electrochemical activities toward the oxygen reduction reaction (ORR). The results demonstrated improved electrocatalytic activity and selectivity with increasing metal concentration. Notably, the electrocatalysts with 6% Mg and 6% Ni doping exhibit superior peroxide scavenging properties. When 6% Ni is mixed with FePc600, it provides additional active sites devoted to the peroxide scavenging increasing the limiting current from 4.69 to 5.62 mA cm^-2, halving the peroxide production, passing from 5.1% to 2.9%. Overall, this study provides insights into the tunable properties of Fe₂O₃@GO composites through metal doping, offering a versatile approach to enhance the performance of composite materials in various technological applications, and specifically suggests that Fe₂O₃ grafted on GO, modified with Mg and Ni, holds significant potential as a cocatalyst for ORR in energy devices such as alkaline fuel cells.