Nickel and cobalt in situ grown in 3-dimensional hierarchical porous graphene for effective methanol electro-oxidation reaction

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2019-04, Vol.838, p.7-15
• Main Authors: Ullah, Nabi, Xie, Meng, Oluigbo, Chidinma Judith, Xu, Yuanguo, Xie, Jimin, Rasheed, Haroon Ur, Zhang, Mingmei
• Format: Article
• Language: English
• Subjects: Catalysis; Co@3DHPG; Cobalt; Current density; Electrocatalysts; Encapsulation; Graphene; In situ grown; Ion exchange; Methanol; Methanol electro-oxidation reaction; Nanoparticles; Ni@3DHPG; Nickel; Oxidation; Silver chloride; Three dimensional composites
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2019.02.022

Here we report, an efficient, cheap and simple strategy to obtain electrocatalysts for methanol electro-oxidation reactions. Nickel encapsulated 3-dimensional hierarchical porous graphene and cobalt encapsulated 3-dimensional hierarchical porous graphene composites are obtained by ion exchange/activation method. The well dispersion of nickel and cobalt nanoparticles are observed inside the nickel encapsulated 3-dimensional hierarchical porous graphene and cobalt encapsulated 3-dimensional hierarchical porous graphene composites respectively. Graphene layer over the metals nanoparticles may suppress metal corrosion and enhance their catalytic performance for methanol electro-oxidation reactions. Nickel encapsulated 3-dimensional hierarchical porous graphene exhibits low onset potential of 0.32V (vs Ag/AgCl) and the highest current density of 147.108mAcm−2 at a low overpotential of 0.728V (vs Ag/AgCl). Similarly, cobalt encapsulated 3-dimensional hierarchical porous graphene shows lower onset potential of 0.45V (vs Ag/AgCl) and high current density of 10mAcm−2 at low overpotential of 0.62V (vs Ag/AgCl). More importantly, better methanol electro-oxidation reaction was recorded in 1M KOH and 0.75M methanol solution with a scan rate of 50mVs−1. The nickel-containing electrocatalyst show better performance than cobalt based electrocatalyst under same conditions. •Ni@3DHPG and Co@3DHPG prepared by single-step from novel and less toxic precursor•Ni@3DHPG and Co@3DHPG highly porous electrocatalysts for methanol activities•Conductive 3DHPG reduced metal corrosion and enhanced electrocatalytic reaction.•Ni@3DHPG is better catalyst than Co@3DHPG for methanol electro-oxidation reaction.