Title: Nanoscale mapping of hydrogen evolution on metallic and semiconducting MoS₂ nanosheets

Abstract

Hydrogen evolution reaction (HER) on molybdenum disulfide (MoS₂) nanosheets is enhanced for the metallic (1T) phase relative to the thermodynamically stable semiconducting (2H) phase. To measure this difference, we employ scanning electrochemical microscopy (SECM) for high-resolution mapping (<20 nm spatial resolution) of surface reactivity for mixed-phase and pure 2H-only MoS₂ nanosheets. For mixed-phase MoS₂ nanosheets, we find major differences in reactivity of the two phases for electron transfer involving ferrocenemethanol, allowing us to locate 1T and 2H regions and directly map the corresponding HER activity. In our measurements, we find that HER is immeasurably slow on the 2H basal plane and much faster on edges, whereas 1T portions are highly reactive across the entire portion. We also use scanning transmission electron microscopy-electron energy loss spectroscopy and scanning Kelvin probe microscopy to corroborate the phase domains and local workfunctions (surface potentials) within the MoS₂ nanosheets; the mixed-phase MoS₂ has a shallower workfunction compared to 2H MoS₂, which could enable a greater driving force for H₂ generation. As a result, this powerful combination of techniques for spatially mapping surface reactivity and correlated phase domains should be applicable to a broad range of materials for HER and other catalysis reactions.

Authors:

Sun, Tong ^[1]; Zhang, Hanyu  ^[2];

• Search DOE PAGES for author "Zhang, Hanyu"
• Search DOE PAGES for ORCID "0000-0001-9942-8186"

Wang, Xiang ^[1]; Liu, Jun ^[2]; Xiao, Chuanxiao  ^[2];

• Search DOE PAGES for author "Xiao, Chuanxiao"
• Search DOE PAGES for ORCID "0000-0002-4136-2249"

Nanayakkara, Sanjini U.  ^[2];

• Search DOE PAGES for author "Nanayakkara, Sanjini U."
• Search DOE PAGES for ORCID "0000-0003-1526-2081"

Blackburn, Jeffrey L.  ^[2];

• Search DOE PAGES for author "Blackburn, Jeffrey L."
• Search DOE PAGES for ORCID "0000-0002-9237-5891"

Mirkin, Michael V.  ^[1];

• Search DOE PAGES for author "Mirkin, Michael V."
• Search DOE PAGES for ORCID "0000-0002-3424-5810"

Miller, Elisa M.  ^[2]

• Search DOE PAGES for author "Miller, Elisa M."
• Search DOE PAGES for ORCID "0000-0002-7648-5433"

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+ Show Author Affiliations

1. Queens College-CUNY, Flushing, NY (United States); Graduate Center of CUNY, New York, NY (United States)
2. National Renewable Energy Lab. (NREL), Golden, CO (United States)

Publication Date:

Thu Nov 29 00:00:00 EST 2018

Research Org.:

National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1524319

Alternate Identifier(s):

OSTI ID: 1484536

Report Number(s):

NREL/JA-5900-71993
Journal ID: ISSN 2055-6756; NHAOAW

Grant/Contract Number:  

AC36-08GO28308

Resource Type:

Accepted Manuscript

Journal Name:

Nanoscale Horizons

Additional Journal Information:

Journal Volume: 4; Journal Issue: 3; Journal ID: ISSN 2055-6756

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; electron energy levels; electron energy loss spectroscopy; electron scattering; energy dissipation; high resolution transmission electron microscopy; hydrogen; layered semiconductors; mapping; nanosheets; scanning; scanning electron microscopy; scanning probe microscopy; sulfur compounds