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ACS Nano. 2018 May 22;12(5):4565-4573. doi: 10.1021/acsnano.8b00942. Epub 2018 Apr 24.

Two-Dimensional MoS2 Confined Co(OH)2 Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes.

Author information

1
Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) , Tsinghua University , Shenzhen 518055 , PR China.
2
Graduate School at Shenzhen , Tsinghua University , Shenzhen 518055 , PR China.
3
Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang , Liaoning 110016 , PR China.

Abstract

The development of abundant and cheap electrocatalysts for the hydrogen evolution reaction (HER) has attracted increasing attention over recent years. However, to achieve low-cost HER electrocatalysis, especially in alkaline media, is still a big challenge due to the sluggish water dissociation kinetics as well as the poor long-term stability of catalysts. In this paper we report the design and synthesis of a two-dimensional (2D) MoS2 confined Co(OH)2 nanoparticle electrocatalyst, which accelerates water dissociation and exhibits good durability in alkaline solutions, leading to significant improvement in HER performance. A two-step method was used to synthesize the electrocatalyst, starting with the lithium intercalation of exfoliated MoS2 nanosheets followed by Co2+ exchange in alkaline media to form MoS2 intercalated with Co(OH)2 nanoparticles (denoted Co-Ex-MoS2), which was fully characterized by spectroscopic studies. Electrochemical tests indicated that the electrocatalyst exhibits superior HER activity and excellent stability, with an onset overpotential and Tafel slope as low as 15 mV and 53 mV dec-1, respectively, which are among the best values reported so far for the Pt-free HER in alkaline media. Furthermore, density functional theory calculations show that the cojoint roles of Co(OH)2 nanoparticles and MoS2 nanosheets result in the excellent activity of the Co-Ex-MoS2 electrocatalyst, and the good stability is attributed to the confinement of the Co(OH)2 nanoparticles. This work provides an imporant strategy for designing HER electrocatalysts in alkaline solutions, and can, in principle, be expanded to other materials besides the Co(OH)2 and MoS2 used here.

KEYWORDS:

Co(OH)2; MoS2; alkaline media; density functional theory; hydrogen evolution reaction; nanoconfinement; two-dimensional materials

PMID:
29688695
DOI:
10.1021/acsnano.8b00942

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