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Crystalline Multi-Metal Nanosheets Array with Enriched Oxygen Vacancies as Efficient and Stable Bifunctional Electrocatalysts for Water Splitting
journal contribution
posted on 2019-11-19, 17:06 authored by Muhammad
Imran Abdullah, Asima Hameed, Tuoping Hu, Ning Zhang, Mingming MaThe electrolysis of water on a large scale for hydrogen
production
needs low cost, efficient, and stable electrocatalysts for the hydrogen
evolution reaction (HER) and oxygen evolution reaction (OER). Herein,
we report the synthesis of a crystalline multimetal (Co, Ni, Fe) nanosheets
array (NSA) enriched with oxygen vacancies by a simple electrosynthesis
method, which can serve as efficient and stable electrocatalysts for
both OER and HER. The oxygen vacancies are generated by electro-oxidation
or electro-reduction of CoFeNiSe precursor via the replacement of
selenium by oxygen. For HER, as synthesized CoFeNi-NSA achieved a
400 mA cm–2 current density at a low overpotential
of −211 mV. For OER, CoFeNi-NSA was in situ oxidized to form
CoFeNiO-NSA, which achieved a 400 mA cm–2 current
density at a low overpotential of 270 mV. The activities of CoFeNi-NSA
and CoFeNiO-NSA remained stable after 150 h HER or OER test at high
current densities, showing higher activity and stability than noble-metal
electrocatalysts Pt/C and IrO2, respectively. The electrolytic
cell of CoFeNiO-NSA∥CoFeNi-NSA can achieve a high current density
of 400 mA cm–2 at a moderate voltage of 1.98 V.
During a long-term water splitting test, the voltage of the electrolytic
cell remained stable at 1.76 V for 150 h at a current density of 120
mA cm–2, indicating that these catalysts have both
high activity and stability for OER and HER reactions.