Enhanced oxygen evolution reaction on polyethyleneimine functionalized graphene oxide in alkaline medium

Abstract

Practical applications of metal free catalysts are hindered by their innate poor stability for electrocatalytic application. Accordingly, in this study, synthesis and functionalization of graphene oxide via a modified Tour's method (GOT) with different amine containing molecules results in excellent catalytic performance and stability toward OER in alkaline medium. The as-synthesized polyethyleneimine GOT electrode (P-GOT), produced current densities of 10, 50 and 100 mA/cm2 at overpotentials of 240, 350 and 420 mV, respectively, with small Tafel slope of 47 mV/dec. The X-ray diffraction analysis (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis confirms the successful functionalization of GOT by ethylenediamine (E) and polyethyleneimine (P) molecules, respectively. Morphological studies based on field emission scanning electron microscopy (FESEM) confirm that the modification via covalent bonding preserved the original wrinkled and layered structure of GOT. The P-GOT with cross-linked amine can expose more active sites and is not easy to peel off, which corresponds to attaining lower charge transfer resistance (1.01Ω cm2) and remarkable current stability in 1.0 M KOH solution, compared to the pristine GOT and E-GOT electrodes. From this perspective, our results therefore provide a valuable route for development and practical application of metal free catalytic materials for water oxidation reaction.