Nanoscale hetero-structured Co−Co(OH)2 composite/amorphous carbon core/shell bi-functional electrocatalysts electrochemically evolved from metastable hexagonal-phase cobalt for overall water splitting. (1st August 2021)

• Record Type: Journal Article
• Authors: Lu, Pai; Chen, Xuyuan
• Is Part Of: Electrochimica acta. Volume 386(2021)
• Publication Date: 2021-08-01
• Subjects: Water splitting -- Bi-functional electrocatalyst -- Nanocomposite -- Cobalt -- Cobalt hydroxide; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.138517
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: Nanowire array electrode assembled by ultrafine Co-Co(OH)2 /C core/shell nanoparticles. Nanoscale Co-Co(OH)2 heterostructure via phase evolution from metastable Hexagonal Co. Mild preparation conditions for carbon coated core/shell nanostructure electrode. Superior bi-functional alkaline electrocatalytic water splitting performance. Abstract: Bi-functional electrocatalysts suited to alkaline water splitting systems are highly pursued, towards the most realistic application enabled by simplified electrolyzer design and cost-effective operation. Herein, a novel nanocomposite Co−Co(OH)2 /C electrocatalyst with nanoscale hetero-structured metastable hexagonal-phase Co (H-Co) crystallites and Co(OH)2 crystallites encapsulated by amorphous carbon shells is developed. We employ a mild thermal decomposition route coupled with in-situ carbon deposition performed at 400 °C to prepare H-Co/C core/shell structured precursor. In a following controllable electrochemical transformation at room temperature the partial conversion of the metastable H-Co to Co(OH)2 leads to the mutual embedding of nanoscale crystalline H-Co and Co(OH)2 confined in the amorphous carbon shells. Taking advantage of the nanowire array morphology, carbon coated core/shell structure, nanoscale size, and the synergistic H-Co and Co(OH)2 bi-components, an outstanding bi-functional electrocatalytic performance for overall water splitting is attained with proved small overpotentials (93 mV for hydrogen evolution reaction, 264 mV for oxygen evolution reaction at 10 mA cm −2 ). Graphical abstract: Image, graphical abstract