Edge-On MoS2 Thin Films by Atomic Layer Deposition for Understanding the Interplay between the Active Area and Hydrogen Evolution Reaction

Thi Anh Ho, Changdeuck Bae, Seonhee Lee, Myungjun Kim, Josep M. Montero-Moreno, Jong Hyeok Park, Hyunjung Shin

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The edge sites of molybdenum disulfide (MoS2) have been shown to be efficient electrocatalysts for the hydrogen evolution reaction (HER). To utilize these structures, two main strategies have been proposed. The first strategy is to use amorphous structures, which should be beneficial in maximizing the area of the edge-site moieties of MoS2. However, these structures experience structural instability during HER. The other strategy is nanostructuring, in which, to enhance the resulting HER performance, the exposed surfaces of MoS2 cannot be inert basal planes. Therefore, MoS2 may need critical nanocrystallinity to produce the desired facets. Here, we first describe that when atomic layer deposition (ALD) is applied to layered materials such as MoS2, MoS2 exhibits the nonideal mode of ALD growth on planar surfaces. As a model system, the ALD of MoCl5 and H2S was studied. This nonideality does not allow for the conventional linear relationship between the growth thickness and the number of cycles. Instead, it provides the ability to control the relative ratios of the edge sites and basal planes of MoS2 to the exposed surfaces. The number of edge sites produced was carefully characterized in terms of the geometric surface area and effective work function and was correlated to the HER performance, including Tafel slopes and exchange current densities. We also discussed how, as a result of the low growth temperature, the incorporation of chlorine impurities affected the electron doping and formation of mixed 2H and 1T phases. Remarkably, the resulting 1T phase was stable even upon thermal annealing at 400 °C. With the simple, planar MoS2 films, we monitored the resulting catalytic performance, finding current densities of up to 20 mA cm-2 at -0.3 V versus the reversible hydrogen electrode (RHE), a Tafel slope of 50-60 mV/decade, and an onset potential of 143 mV versus RHE.

Original languageEnglish
Pages (from-to)7604-7614
Number of pages11
JournalChemistry of Materials
Volume29
Issue number17
DOIs
Publication statusPublished - 2017 Sep 12

Fingerprint

Atomic layer deposition
Hydrogen
Thin films
Current density
Electrodes
Electrocatalysts
Chlorine
Growth temperature
Molybdenum
Doping (additives)
Annealing
Impurities
Electrons

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cite this

Ho, Thi Anh ; Bae, Changdeuck ; Lee, Seonhee ; Kim, Myungjun ; Montero-Moreno, Josep M. ; Park, Jong Hyeok ; Shin, Hyunjung. / Edge-On MoS2 Thin Films by Atomic Layer Deposition for Understanding the Interplay between the Active Area and Hydrogen Evolution Reaction. In: Chemistry of Materials. 2017 ; Vol. 29, No. 17. pp. 7604-7614.
@article{d5fdfc02b0ea4134b4d85049c22139a7,
title = "Edge-On MoS2 Thin Films by Atomic Layer Deposition for Understanding the Interplay between the Active Area and Hydrogen Evolution Reaction",
abstract = "The edge sites of molybdenum disulfide (MoS2) have been shown to be efficient electrocatalysts for the hydrogen evolution reaction (HER). To utilize these structures, two main strategies have been proposed. The first strategy is to use amorphous structures, which should be beneficial in maximizing the area of the edge-site moieties of MoS2. However, these structures experience structural instability during HER. The other strategy is nanostructuring, in which, to enhance the resulting HER performance, the exposed surfaces of MoS2 cannot be inert basal planes. Therefore, MoS2 may need critical nanocrystallinity to produce the desired facets. Here, we first describe that when atomic layer deposition (ALD) is applied to layered materials such as MoS2, MoS2 exhibits the nonideal mode of ALD growth on planar surfaces. As a model system, the ALD of MoCl5 and H2S was studied. This nonideality does not allow for the conventional linear relationship between the growth thickness and the number of cycles. Instead, it provides the ability to control the relative ratios of the edge sites and basal planes of MoS2 to the exposed surfaces. The number of edge sites produced was carefully characterized in terms of the geometric surface area and effective work function and was correlated to the HER performance, including Tafel slopes and exchange current densities. We also discussed how, as a result of the low growth temperature, the incorporation of chlorine impurities affected the electron doping and formation of mixed 2H and 1T phases. Remarkably, the resulting 1T phase was stable even upon thermal annealing at 400 °C. With the simple, planar MoS2 films, we monitored the resulting catalytic performance, finding current densities of up to 20 mA cm-2 at -0.3 V versus the reversible hydrogen electrode (RHE), a Tafel slope of 50-60 mV/decade, and an onset potential of 143 mV versus RHE.",
author = "Ho, {Thi Anh} and Changdeuck Bae and Seonhee Lee and Myungjun Kim and Montero-Moreno, {Josep M.} and Park, {Jong Hyeok} and Hyunjung Shin",
year = "2017",
month = "9",
day = "12",
doi = "10.1021/acs.chemmater.7b03212",
language = "English",
volume = "29",
pages = "7604--7614",
journal = "Chemistry of Materials",
issn = "0897-4756",
publisher = "American Chemical Society",
number = "17",

}

Edge-On MoS2 Thin Films by Atomic Layer Deposition for Understanding the Interplay between the Active Area and Hydrogen Evolution Reaction. / Ho, Thi Anh; Bae, Changdeuck; Lee, Seonhee; Kim, Myungjun; Montero-Moreno, Josep M.; Park, Jong Hyeok; Shin, Hyunjung.

In: Chemistry of Materials, Vol. 29, No. 17, 12.09.2017, p. 7604-7614.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Edge-On MoS2 Thin Films by Atomic Layer Deposition for Understanding the Interplay between the Active Area and Hydrogen Evolution Reaction

AU - Ho, Thi Anh

AU - Bae, Changdeuck

AU - Lee, Seonhee

AU - Kim, Myungjun

AU - Montero-Moreno, Josep M.

AU - Park, Jong Hyeok

AU - Shin, Hyunjung

PY - 2017/9/12

Y1 - 2017/9/12

N2 - The edge sites of molybdenum disulfide (MoS2) have been shown to be efficient electrocatalysts for the hydrogen evolution reaction (HER). To utilize these structures, two main strategies have been proposed. The first strategy is to use amorphous structures, which should be beneficial in maximizing the area of the edge-site moieties of MoS2. However, these structures experience structural instability during HER. The other strategy is nanostructuring, in which, to enhance the resulting HER performance, the exposed surfaces of MoS2 cannot be inert basal planes. Therefore, MoS2 may need critical nanocrystallinity to produce the desired facets. Here, we first describe that when atomic layer deposition (ALD) is applied to layered materials such as MoS2, MoS2 exhibits the nonideal mode of ALD growth on planar surfaces. As a model system, the ALD of MoCl5 and H2S was studied. This nonideality does not allow for the conventional linear relationship between the growth thickness and the number of cycles. Instead, it provides the ability to control the relative ratios of the edge sites and basal planes of MoS2 to the exposed surfaces. The number of edge sites produced was carefully characterized in terms of the geometric surface area and effective work function and was correlated to the HER performance, including Tafel slopes and exchange current densities. We also discussed how, as a result of the low growth temperature, the incorporation of chlorine impurities affected the electron doping and formation of mixed 2H and 1T phases. Remarkably, the resulting 1T phase was stable even upon thermal annealing at 400 °C. With the simple, planar MoS2 films, we monitored the resulting catalytic performance, finding current densities of up to 20 mA cm-2 at -0.3 V versus the reversible hydrogen electrode (RHE), a Tafel slope of 50-60 mV/decade, and an onset potential of 143 mV versus RHE.

AB - The edge sites of molybdenum disulfide (MoS2) have been shown to be efficient electrocatalysts for the hydrogen evolution reaction (HER). To utilize these structures, two main strategies have been proposed. The first strategy is to use amorphous structures, which should be beneficial in maximizing the area of the edge-site moieties of MoS2. However, these structures experience structural instability during HER. The other strategy is nanostructuring, in which, to enhance the resulting HER performance, the exposed surfaces of MoS2 cannot be inert basal planes. Therefore, MoS2 may need critical nanocrystallinity to produce the desired facets. Here, we first describe that when atomic layer deposition (ALD) is applied to layered materials such as MoS2, MoS2 exhibits the nonideal mode of ALD growth on planar surfaces. As a model system, the ALD of MoCl5 and H2S was studied. This nonideality does not allow for the conventional linear relationship between the growth thickness and the number of cycles. Instead, it provides the ability to control the relative ratios of the edge sites and basal planes of MoS2 to the exposed surfaces. The number of edge sites produced was carefully characterized in terms of the geometric surface area and effective work function and was correlated to the HER performance, including Tafel slopes and exchange current densities. We also discussed how, as a result of the low growth temperature, the incorporation of chlorine impurities affected the electron doping and formation of mixed 2H and 1T phases. Remarkably, the resulting 1T phase was stable even upon thermal annealing at 400 °C. With the simple, planar MoS2 films, we monitored the resulting catalytic performance, finding current densities of up to 20 mA cm-2 at -0.3 V versus the reversible hydrogen electrode (RHE), a Tafel slope of 50-60 mV/decade, and an onset potential of 143 mV versus RHE.

UR - http://www.scopus.com/inward/record.url?scp=85029307807&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85029307807&partnerID=8YFLogxK

U2 - 10.1021/acs.chemmater.7b03212

DO - 10.1021/acs.chemmater.7b03212

M3 - Article

AN - SCOPUS:85029307807

VL - 29

SP - 7604

EP - 7614

JO - Chemistry of Materials

JF - Chemistry of Materials

SN - 0897-4756

IS - 17

ER -