3D graphene decorated with hexagonal micro-coin of Co(OH)2: A competent electrocatalyst for hydrogen and oxygen evolution reaction

• Published in: International journal of hydrogen energy 2019-06, Vol.44 (29), p.14770-14779
• Main Authors: Ullah, Nabi, Shah, Sayyar Ali, Xie, Meng, Rasheed, Haroon Ur, Oluigbo, Chidinma Judith, Jiang, Di, Xu, Yuanguo, Xie, Jimin
• Format: Article
• Language: English
• Subjects: 3D graphene; Co(OH)2; HER; Hexagonal micro-coin; OER
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2019.03.278

Herein, 3D graphene is synthesized from the cation exchange resin by a cheap and efficient strategy, and then hexagonal micro-coin Co(OH)2 particles are loaded by a simple double displacement reaction. Different analytical techniques confirm that the 3D graphene exhibit rose petal-like structure, which is decorated with Co(OH)2 hexagonal micro coin structure. The hexagonal micro-coin Co(OH)2 are the actual active sites for electrochemical reactions, while conductive graphene eases the transport of electrons which may further heighten their performance. The as-synthesized electrocatalysts are used to study different electrochemical measurement in an alkaline (1 M KOH) solution. The as-prepared Co(OH)2-3 dimensional graphene-0.5 delivered the overpotential value of −0.367 and 1.599 V (vs RHE) (10 mA cm−2), the calculated Tafel slope values were 96 and 110 mV dec−1 for hydrogen and oxygen evolution reactions correspondingly. Different concentrations of Co were used to study the effect of Co on electrochemical measurements. The data shows that Co(OH)2-3DG-0.5 exhibited better performance than the other as-prepared Co(OH)2 based electrocatalysts. The as-prepared electrocatalyst also shows low Rct and reasonable stability for hydrogen and oxygen evolution reaction. Hexagonal micro coin-like Co(OH)2 particles on the surface of 3D graphene are the active site for reaction and conductivity of graphene layer facilitate fast transport of electron, which leads the efficient catalytic activity and stability for OER and HER. [Display omitted] •A novel and less toxic precursor is used to synthesize 3D graphene.•3D graphene composed of rose petal-like lamella, loaded with coin-like Co(OH)2.•The Co(OH)2 3D graphene exhibits better HER and OER activity and stability.•High exposed edges of coin-like Co(OH)2 particles leads to good activity.