One-step synthesis of zinc–cobalt layered double
hydroxide (Zn–Co-LDH) nanosheets for high-
efficiency oxygen evolution reaction†
Chen Qiao,
a
Yuan Zhang,
ac
Youqi Zhu,
b
Chuanbao Cao,
b
Xinhua Bao
*
a
and Jiaqiang Xu
*
a
Two-dimensional (2D) nanomaterials show great potential for electrocatalysis or other applications that
require large surface area. In this work, we developed porous zinc–cobalt layered double hydroxide (Zn–
Co-LDH) nanosheets by using a one-step microwave-assisted approach, and examine their oxygen
evolution reaction (OER) performance. The Zn–Co-LDH nanosheets with a high specific surface area of
116.4 m
2
g
1
exhibit good OER activity, expressed as low onset overpotential, small Tafel slope and large
exchange current density. At the overpotential of 0.54 V, the current density of Zn–Co-LDH nanosheets
is about 15.06 mA cm
2
, which is much higher than that of Zn–Co-LDH nanoparticles. The comparable
electrocatalytic performance may be attributed to the porous 2D structure generating more active sites
and higher electronic conductivity. Furthermore, the obtained Zn–Co-LDH nanosheets show good
stability during long time running at 1.55 V vs. RHE. Accordingly, an effective OER catalyst is exploited by
using a simple microwave-assisted synthesis. Such an effective method could be extended to large-scale
synthesis of uniform and stable 2D LDH nanomaterials.
Introduction
Nowadays, the exhaustion of traditional energy and the deteri-
oration of the environment are serious considerations in
current society.
1–4
Hence, topics that nd efficient electro-
catalysts to solve energy problems are arousing the interest of
many researchers. Oxygen evolution reaction (OER) is an
important half reaction involved in many energy conversion
and storage processes such as water splitting.
5,6
Many
researches have been focused on the design and controllable
synthesis of OER catalysts. Noble metal catalysts like RuO
2
and
IrO
2
exhibit high performance.
7,8
Zhongbin Zhuang and co-
workers
9
found that monodispersed Au@Co
3
O
4
core–shell
exhibited excellent catalytic activity and great stability for OER
in alkali solution. Tobias Reier and co-workers
10
reported that Ir
nanoparticles showed good stability and high OER activity as
nanoscaled OER catalyst. However, new catalysts with low cost,
high activity and enhanced OER kinetics are continuously in
great demand.
11–17
Layered double hydroxides (LDHs) are a class of layered
materials, in which the positively charged layers contain alter-
nately arranged metal cations (they are commonly divalent and
trivalent, although monovalent metal cations are also
known
18,19
) balanced by charge-compensating anions posi-
tioned within the interlayer space. Due to the rapid develop-
ment of electrocatalysts, the study of LDHs for OER has
attracted much attention.
20–22
Tewodros Asefa and co-workers
18
reported that the bimetallic Zn–Co layered double hydroxide
(Zn–Co-LDH) can serve as an efficient electrocatalyst for water
and alcohol oxidation.
Two-dimensional (2D) materials have larger active surface
areas compared with other bulk counterparts.
23–28
Norskøv and
coworkers used density functional theory (DFT) to build a
theoretical model for hydrogen evolution reaction (HER) based
on the calculated adsorption energies.
29–31
In accordance with
their results, the edge of lamellar MoS
2
revealed reasonably
high activity.
32
Hongjie Dai and his co-workers
33
found that
NiFe-LDH nanoplates were highly active for oxygen evolution
reaction in alkaline solutions. Fang Song and Xile Hu
34
showed
that the higher OER activity of exfoliated LDHs was mainly
attributed to an increase in the number of active edge sites and
the higher electronic conductivity.
Liquid exfoliation of layered materials has emerged as a
conventional method in producing novel two-dimensional
materials.
35–37
However, because of the low yield and complex
synthesis of two-dimensional materials from liquid exfoliation,
it is expected to nd simple and effective new ways to prepare
a
Department of Chemistry, Shanghai University, Shanghai 200444, China. E-mail:
xujiaqiang@shu.edu.cn
b
Research Center of Materials Science, Beijing Institute of Technology, Beijing 100081,
China. E-mail: cbcao@bit.edu.cn; Fax: +86 10 68912001; Tel: +86 10 68913792
c
State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem
and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
† Electronic supplementary information (ESI) available: Turnover frequency (TOF)
calculation and electrochemical measurements. See DOI: 10.1039/c4ta06643k
Cite this: J. Mater. Chem. A,2015,3,
6878
Received 3rd December 2014
Accepted 3rd February 2015
DOI: 10.1039/c4ta06634k
www.rsc.org/MaterialsA
6878 | J. Mater. Chem. A,2015,3,6878–6883 This journal is © The Royal Society of Chemistry 2015
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