Abstract
Despite an increased interest in sustainable energy conversion systems, there have been limited studies investigating the electrocatalytic reaction mechanism of methanol oxidation on Ni-based amorphous materials in alkaline media. A thorough understanding of such mechanisms would aid in the development of amorphous catalytic materials for methanol oxidation reactions. In the present work, amorphous Ni-B and Ni-B-Co nanoparticles were prepared by a simple chemical reduction, and their electrocatalytic properties were investigated by cyclic voltammetry measurements. The diffusion coefficients (D0) for Ni-B, Ni-B-Co0.02, Ni-B-Co0.05, and Ni-B-Co0.1 nanoparticles were calculated to be 1.28 × 10−9, 2.35 × 10−9, 4.48 × 10−9 and 2.67 × 10−9 cm2 s−1, respectively. The reaction order of methanol in the studied transformation was approximately 0.5 for all studied catalysts, whereas the reaction order of the hydroxide ion was nearly 1. The activation energy (Ea) values of the reaction were also calculated for the Ni-B and Ni-B-Co nanoparticle systems. Based on our kinetic studies, a mechanism for the methanol oxidation reaction was proposed which involved formation of an electrocatalytic layer on the surface of amorphous Ni–B and Ni-B-Co nanoparticles. And methanol and hydroxide ions could diffuse freely through this three-dimensional porous conductive layer.
Highlights
Direct methanol fuel cells (DMFCs) have become popular for use in portable electronic devices, such as cell phones and laptops as well as in the transportation sector, due to their high energy density and quick refueling characteristics [1,2]
The electrocatalytic reaction mechanism of methanol oxidation catalyzed by amorphous Ni-B and
The activation energy (Ea ) values for the Ni-B methanol oxidation system was lower than the Ni-B-Co nanoparticles
Summary
Direct methanol fuel cells (DMFCs) have become popular for use in portable electronic devices, such as cell phones and laptops as well as in the transportation sector, due to their high energy density and quick refueling characteristics [1,2]. DMFCs typically require expensive and scarce noble metal Pt-Ru catalysts at the anode for methanol oxidations; there is a demand for the design of highly efficient and cost-effective alternatives [3,4,5]. Ni-based catalysts which are currently regarded as one of the most promising alternatives due to their respectable electrocatalytic activity toward methanol oxidations under alkaline conditions [6,7]. Dopant atoms, particle sizes, and substrates have been studied in an effort to improve their electrocatalytic methanol oxidation reactivity. Heterostructures composed of Ni cores partially encapsulated within the surface-oxidized layers of NiO were synthesized with low Ni loadings, exhibiting enhanced catalytic activity and stability for methanol oxidations [9]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have