Phosphine-Functionalized Graphene Oxide, A High PerformanceElectrocatalyst for Oxygen Reduction Reaction

Recent interests in generating a sustainable energy economy have given much interest to the concept of the hydrogen economy1. Fuel cells have drawn substantial interest as energy production devices, due to their potentials in low pollution output and high theoretical energy densities. Proton exchange membrane fuel cells (PEMFCs) are, arguably, the most commercialized fuel cells, but one of the key practical challenge for PEMFCs is the slow cathodic kinetics of oxygen reduction reaction (ORR) at the cathode that reduces the performance of fuel cells. Another major challenge is the high cost of Platinum based catalysts. Also platinum can suffer from strong adsorption of carbon monoxide (CO) at the platinum surface and blockingthe active sites, so dictating the use of highly purified hydrogen sources. Among the various alternatives for Pt-based catalyst, carbon-based materials are of great interest as non-precious metal catalysts for the ORR due to their relatively high activity and superior stability2.Here, a novel approach for the preparation of phosphine-functionalized graphene oxide (GOPPh2) is developed. Using a simple method, diphenylphosphine group was linked to the hydroxyl group of OH-functionalized graphene. The GO-PPh2 catalyst was characterized using some different microscopic and spectroscopic techniques including XPS, XRD, TGA, SEM and FT-IR analysis. The electrocatalytic activities of GO-PPh2, rGO, and Pt/C toward the ORR were studiedusing linear sweep voltammetry (LSV) in N2 and O2 saturated 0.1 mol L‒1 KOH solution, from +0.20 V to ‒0.60 V vs. Ag/AgCl and at a scan rate of 10 mV s‒1 for GO-PPh2, rGO, and Pt/C catalysts displayed featureless curves in N2-saturated solution. On the other hand, the LSV curves present a well-defined ORR peak in O2-saturated solution for proposed electrocatalysts, whichdemonstrate the good electrocatalytic activity of GO-PPh2 in comparison with unmodified glassy carbon electrode and rGO modified glassy carbon electrode catalyst toward the ORR.

Keywords:

Graphene Oxide , Phosphine-Functionalized , Oxygen Reduction Reaction , Electrocatalyst