Silver-integrated cobalt hydroxide hybrid nanostructured materials for improved electrocatalytic oxygen evolution reaction

• Published in: New journal of chemistry 2024-01, Vol.48 (4), p.1671-1677
• Main Authors: Arunkumar, Gunasekaran, Muthukumar, Pandi, Deviga, Govindan, Mariappan, Mariappan, Pannipara, Mehboobali, Al-Sehemi, Abdullah G, Anthony, Savarimuthu Philip
• Format: Article
• Language: English
• Subjects: Charge transfer; Cobalt; Current density; Electrocatalysts; Nanostructured materials; Oxidation; Oxygen evolution reactions; Photoelectrons; Reaction kinetics; Silver; Valence; X ray photoelectron spectroscopy
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d3nj05268k

Cobalt hydroxide Co(OH) 2 is considered to be a potential material for electrocatalyst, especially for oxygen evolution reaction (OER), owing to the earth's abundance, environmentally benign nature, and redox-active properties of cobalt. Herein, we report the fabrication of pristine Co(OH) 2 and AgNP-integrated Co(OH) 2 (Ag-Co(OH) 2 ) by simple wet chemical methods and explore the electrocatalytic OER activity in the alkaline medium. High-resolution transmission electro-microscopic (HR-TEM) analysis revealed featureless nanostructures for Co(OH) 2 with coexisting amorphous and crystalline phases, as well as the inclusion of crystalline AgNPs in Ag-Co(OH) 2 . X-ray photoelectron spectroscopic (XPS) analysis confirmed the inclusion of metallic AgNPs and the presence of Co at a mixed oxidation state. Electrocatalytic OER studies indicated that pristine Co(OH) 2 required the overpotential of 299 mV to achieve a geometric current density of 10 mA cm −2 . The integration of AgNPs in Co(OH) 2 (Ag-Co(OH) 2 ) showed a gradual improvement in the OER activity. The optimized sample, Ag-Co(OH) 2 -5, required the overpotential of 253 mV to produce 10 mA cm −2 current density. Tafel slope analysis revealed a lower value upon AgNP integration and electrochemical impedance showed lower charge transfer resistance. The lower Tafel value and charge transfer resistance of Ag-Co(OH) 2 -5 indicated good chemical coupling and faster reaction kinetics at the electrode surface. AgNPs incorporation with Co(OH) 2 also showed enhanced turn-over frequency, electrochemical active surface area, and double-layer capacitance. The fabricated hybrid Ag-Co(OH) 2 -5 catalyst also exhibited good stability over 60 h. Thus, the electrocatalytic activity of low-cost Co(OH) 2 was improved by fabricating coexisting amorphous and crystalline phases and integrating noble silver nanoparticles. Synthesizing Co(OH) 2 with coexisting amorphous and crystalline phases showed strong electrocatalytic OER activity in the alkaline medium. The OER activity of Co(OH) 2 was further improved upon the integration of AgNPs.