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A NiCo 2 O 4 Shell on a Hollow Ni Nanorod Array Core for Water Splitting with Enhanced Electrocatalytic Performance
Author(s) -
Wang Luyu,
Gu Changdong,
Ge Xiang,
Zhang Jialei,
Zhu Hongyi,
Tu Jiangping
Publication year - 2018
Publication title -
chemnanomat
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.947
H-Index - 32
ISSN - 2199-692X
DOI - 10.1002/cnma.201700291
Subject(s) - overpotential , electrocatalyst , bifunctional , water splitting , oxygen evolution , nanorod , materials science , electrode , electrochemistry , catalysis , chemical engineering , nickel , electrolyte , cobaltite , nanotechnology , chemistry , metallurgy , photocatalysis , biochemistry , engineering
Nickel cobaltite (NiCo 2 O 4 ) nanostructures have been considered as promising bifunctional electrocatalyst materials for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolyte. However, the activity of these materials toward overall water splitting is still unsatisfactory because a larger voltage is needed to drive the reactions. This study shows that more‐efficient bifunctional catalysts based on NiCo 2 O 4 materials can be obtained by adopting an integrated composite electrode with robust hollow structures. This novel electrode is constructed by the growth of hollow Ni@NiCo 2 O 4 nanorod arrays on three‐dimensional (3D) Ni foam. The interlayer of Ni hollow nanorods is conformally covered by NiCo 2 O 4 nanosheets, providing large surface area and fast electron transport. Benefiting from these integrated characteristics, the hollow Ni@NiCo 2 O 4 electrode as an oxygen evolution electrocatalyst can deliver a low overpotential of 270 mV at 10 mA cm −2 and present excellent electrochemical durability. Meanwhile, the HER performance also impressive, with an overpotential of about 87 mV at 10 mA cm −2 . As a result, the hollow Ni@NiCo 2 O 4 electrode as a bifunctional catalyst can achieve a current density of 10 mA cm − 2 with a voltage of only 1.58 V, showing promise for high performance yet cheap electrocatalysts for the overall water splitting reactions.