Journal
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Volume 622, Issue -, Pages 728-737Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2022.04.150
Keywords
Overall water splitting; Bi-functional electrocatalysts; Nickel sulfides; Heterostructures; In-situ reconstruction
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By introducing facile O2-plasma activation, bi-functional electrocatalysts with improved performance are constructed via nickel sulfide-oxide heterostructures. The activated Ni3S2-NiOx exhibits lower overpotentials for both HER and OER reactions and a lower voltage for overall water splitting.
Bi-functional electrocatalysts are desired for both hydrogen and oxygen evolution reactions (HER and OER). Herein, facile O2-plasma activation is introduced to improve the bi-functionality via constructing nickel sulfide-oxide heterostructures. Ni3S2-NiOx supported by nickel foam delivers obviously elevated HER and OER activity in comparison with pristine Ni3S2 and recently reported NiSx-based electrocatalysts, featured by the low overpotentials for HER (104 mV) and OER (241 mV) at +/- 10 mA cm-2 in 1.0 M KOH, as well as a voltage of 1.52 V for overall water splitting. As revealed by in-situ Raman spectroscopy, on the one hand, Ni(OH)2 generated from Ni3S2 during alkaline HER accelerates water dissociation toward the gradually improved performance; on the other hand, this heterostructure undergoes extensive oxidation during OER, leading to excessive NiOOH covering on Ni3S2 and thereby declining activity. These changes are interpreted by the distinct thermodynamic relationship under specific electro-chemical conditions via density functional theory calculations. (c) 2022 Elsevier Inc. All rights reserved.
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