Stimulation of ethylene glycol electrooxidation on electrodeposited Ni–PbO2–GN nanocomposite in alkaline medium

Abstract

In this work, a novel system composed of non-precious nickel-based metal oxide/reduced graphene oxide nanocomposite (Ni–PbO2–GN) is used for electrooxidation of ethylene glycol (EG) in 1.0 M NaOH solution and compares its activity with that of Ni, Ni–GN, and Ni–PbO2. The facile electrodeposition technique is used to prepare the catalysts on glassy carbon (GC) substrates. The outcomes of electrochemical measurements show a high performance towards EG oxidation is obtained for Ni-nanocomposite electrodes compared to that of Ni mainly due to their higher surface areas. The excellent electrocatalytic properties of the Ni-nanocomposite could be ascribed to the synergistic contributions of PbO2 and graphene (GN) nano-sheets that help the reduction of Ni grains. A smaller charge transfer resistance value of 34.5 Ω cm2 for EG oxidation reaction at + 360 mV is recorded for GC/Ni–PbO2–GN compared to the other prepared electrodes. Moreover, it exhibits higher kinetic parameters of EG such as diffusion coefficient (D = 3.9 × 10–10 cm2 s−1) and charge transfer rate constant (ks = 32.5 mol−1 cm3 s−1). The overall performance and stability of the prepared catalysts towards EG electrooxidation have been estimated to be in the order of GC/Ni–PbO2–GN > GC/Ni–GN > GC/Ni–PbO2 > GC/Ni. Graphical abstract

A novel Ni–Schiff base complex for motivating glucose electrooxidation in alkaline solutions

“…8b) show seven peaks at binding energies of 855.91, 859.75, 863.23, 867.3, 872.66, 875.6, and 880.05 eV. The peaks that appeared at 855.91 and 859.75 eV are assigned to Ni 2+ 2p3/2 of Ni(OH) 2 and Ni 3+ 2p3/2 of NiOOH, 31,61 respectively. The peak at 863.23 eV is a satellite peak of Ni 2+ 2p3/2 and the peak at 867.3 eV is a satellite peak of Ni 3+ 2p3/2.…”

“…7). Two well defined peaks are observed in both anodic and cathodic half cycles (black lines) at 0.55 and 0.38 V, probably due to the formation of the NiOOH and Ni(OH) 2 redox couple, respectively, 31,57,58 according to eqn (13) and (14):[Ni( ii )–SB] + OH − → [Ni( ii )–SB(OH)] − [Ni( ii )–SB(OH)] − = [Ni( iii )–SB(OH)] + e − …”

“…[18][19][20][21][22][23][24] Focusing on nonnoble catalysts, nickel and nickel hydroxide exhibited a promising electrocatalytic performance in alkaline medium due to their low cost, high activity and the possibility of stimulating electron transfer reactions at lower overpotentials. [25][26][27][28][29][30][31] Moreover, the literature reported that nickel complexes as catalysts showed excellent catalytic activity for oxidation of alcohols in alkaline medium due to the formation of NiOOH species. [32][33][34] The glucose oxidation products were studied and well established on Ni based electrodes in the literature by many authors, where gluconolactone was formed as an oxidation product in alkaline solution.…”