Published May 2018 | Version v1
Journal article Metadata-only

Novel insight into the epitaxial growth mechanism of six-fold symmetrical β-Co(OH)2/Co(OH)F hierarchical hexagrams and their water oxidation activity

Creators

  • 1. Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119 (China)
  • 2. Department of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm (Sweden)
  • 3. Department of Chemistry, Renmin University of China, Beijing, 100872 (China)
  • 4. College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871 (China)

Description

Highlights: • The formation process of novel β-Co(OH)2/Co(OH)F hexagrams were reported. • The Co(OH)F nanorods grow along β-Co(OH)2 hexagon edges as lateral branches. • .The lattice matching between Co(OH)F and β-Co(OH)2 leads to the epitaxial growth. • The hybrids show high OER performance. The six-fold symmetry widely presents in both natural and artificial architectures. Understanding the growth mechanism of six-fold symmetrical materials is of fundamental interest and significance. Herein, we report the formation process of β-Co(OH)2/Co(OH)F hierarchical hexagrams with a six-fold symmetrical arrangement. Our results demonstrate that hexagonal β-Co(OH)2 plates are first formed under the reaction condition. These hexagonal plates then act as templates for the growth of Co(OH)F nanorods. The intermediate material is therefore composed of plate-like β-Co(OH)2 hexagonal cores appended with six rod-like Co(OH)F branches, giving the β-Co(OH)2/Co(OH)F hybrid. After prolonged reaction, the β-Co(OH)2 hexagons can be completely converted, leading to authentic six-branched Co(OH)F nanorods as the final product. Consequently, for both intermediate and final materials, the Co(OH)F nanorods are arranged with a six-fold symmetry. Importantly, these Co(OH)F nanorods grow along β-Co(OH)2 hexagon edges as lateral branches instead of perpendicular to hexagons. This uncommon epitaxial growth mechanism is considered to be a result of the matching between the b-axis of Co(OH)F crystals and the a-axis of β-Co(OH)2 crystals, which is beneficial for the electrocatalysis. The β-Co(OH)2/Co(OH)F hierarchical hexagrams show enhanced water oxidation activity compared to the pure β-Co(OH)2 and Co(OH)F.

Availability note (English)

Available from http://dx.doi.org/10.1016/j.electacta.2018.03.186

Additional details

Identifiers

DOI
10.1016/j.electacta.2018.03.186;
PII
S0013468618307126;

Publishing Information

Journal Title
Electrochimica Acta
Journal Volume
271
Journal Page Range
p. 526-536
ISSN
0013-4686
CODEN
ELCAAV

INIS

Country of Publication
United Kingdom
Country of Input or Organization
International Atomic Energy Agency (IAEA)
INIS RN
53033338
Subject category
S77: NANOSCIENCE AND NANOTECHNOLOGY;
Descriptors DEI
COBALT HYDROXIDES; CRYSTALS; ELECTROCATALYSTS; EPITAXY; FLUORINE COMPOUNDS; NANOSTRUCTURES; OXIDATION; SYMMETRY
Descriptors DEC
CATALYSTS; CHEMICAL REACTIONS; COBALT COMPOUNDS; CRYSTAL GROWTH METHODS; HALOGEN COMPOUNDS; HYDROGEN COMPOUNDS; HYDROXIDES; OXYGEN COMPOUNDS; TRANSITION ELEMENT COMPOUNDS

Optional Information

Copyright
Copyright (c) 2018 Elsevier Ltd. All rights reserved.