Electrocatalytic Oxidation of Ethanol on Flexible Three‐dimensional Interconnected Nickel/Gold Composite Foams in Alkaline Media

Abstract

In this work, a porous and flexible three‐dimensional (3D) nickel/gold nanoparticle electrode (NiF/AuNPs) is presented as an efficient electrocatalyst for ethanol oxidation in alkaline media. The 3D nanocomposite electrode consists of interconnected porous nickel foam (NiF) with large pores (500±200 μm diameter) surrounded by interconnected struts (∼100 μm) that are decorated with gold nanoparticles (AuNPs, 37±8 nm) through in‐situ electrochemical deposition. The catalytic performance of the 3D electrode was evaluated by different electrochemical methods. An enhancement in the performance (about 253 %) and a remarkable decline in onset potential (about ∼0.63 V) in comparison with pristine NiF for ethanol oxidation are demonstrated. This potential is lower than many reported results except palladium‐ and platinum‐based catalysts, which are expensive. It is shown that both hydroxyl anions and cations affect the ethanol oxidation on the 3D electrode. The interconnected porous structure provides efficient mass diffusivity, which along with its high specific surface area combined with the catalytic nature of AuNPs, may open new opportunities for in‐inexpensive and highly efficient electro‐oxidation of ethanol for energy applications.

A comprehensive and critical review of the recent progress in electrocatalysts for the ethanol oxidation reaction

“…The effects of oxidation conditions, electrode structure, incorporation of gold nanoparticles, and resistance were also thoroughly studied. 167 …”

Advanced Catalytic Materials for Ethanol Oxidation in Direct Ethanol Fuel Cells

“…Nickel metal is prone to surface oxidation and tends to form NiOOH, especially in alkaline solution, which can promote the oxidation of CO adsorbed on the surface during EOR process [110]. Interested readers can refer to the comprehensive review on Ni-based catalysts for ethanol electro-oxidation [14].…”

“…This can be applied for large-area growth of Ni nanoparticles on various substrates. In addition, Ni foam was employed as a substrate and subjected to in-situ electrodeposition of Au nanoparticles to form three-dimensional (3D) interconnected Ni/Au foams [110] (Figure 9a-c). The porous Ni foam/Au composite catalysts exhibit greatly improved catalytic activity for EOR when compared to Ni foam without Au and Ni foil with Au deposition.…”

Activating bulk nickel foam for the electrochemical oxidization of ethanol by anchoring MnO2@Au nanorods

“…However, the powdery catalysts lm can easily peel off during long-term testing, especially at large current density and under turbulent electrolyte ow in practical applications. 19 Compared with powdery oxides, the use of bulk nickel metal can mitigate the above drawbacks and offer certain advantages: (1) the generation of a dense surface oxide layer on the bulk nickel surface is inevitable, meaning that active NiOOH on the surfaces of bulk nickel metal can be also generated for the EOR in alkaline solution; 16,20 (2) bulk nickel metal can be easily processed and manufactured into various shapes according to the practical requirements, which allows it to serve as both a substrate for conducting current and as a catalyst for enhancing EOR, promising long-term stability. 19,21 However, the surface area of bulk nickel metal is severely decreased when compared with its powdery counterparts, meaning there are much fewer active sites for the former case.…”