TY - JOUR
T1 - Role of anionic vacancy for active hydrogen evolution in WTe2
AU - Kwon, Hagyeong
AU - Ji, Byungdo
AU - Bae, Dongyeon
AU - Lee, Jun Ho
AU - Park, Hee Jung
AU - Kim, Do Hyun
AU - Kim, Young Min
AU - Son, Young Woo
AU - Yang, Heejun
AU - Cho, Suyeon
N1 - Publisher Copyright:
© 2020
PY - 2020/6/15
Y1 - 2020/6/15
N2 - Transition metal dichalcogenides (TMDs) have been investigated for use in a hydrogen evolution reaction (HER), mostly in the form of nano-sized flakes, due to the abundant active site formation by nanostructuring, surface functionalization, and phase engineering. However, the physical origin of the active HER on TMDs remains to be clarified. Here, we investigate the role of anion vacancies for the HER on the basal plane of single-crystalline tungsten dichalcogenide (WTe2), a group 6 metallic TMD. The WTe2 with a small amount of anionic (Te) vacancies shows an improved overpotential from –0.707 to –0.568 V and a constant Tafel slope of 154 mV/dec in the HER. Photoemission spectroscopy, combined with first-principle calculations, reveals that the work function of WTe2 is decreased by the anionic Te vacancies, which improves the bulk conductivity and the overpotential in the HER with the material. Moreover, the enlarged electrochemical active surface area with a large number of Te vacancies in the WTe2 critically improves the HER performance with decreases in the overpotential and the Tafel slope, –0.119 V and 79 mV/dec, respectively. Our results show that the modulation of work function and surface morphology is a promising way to improve the HER in TMDs.
AB - Transition metal dichalcogenides (TMDs) have been investigated for use in a hydrogen evolution reaction (HER), mostly in the form of nano-sized flakes, due to the abundant active site formation by nanostructuring, surface functionalization, and phase engineering. However, the physical origin of the active HER on TMDs remains to be clarified. Here, we investigate the role of anion vacancies for the HER on the basal plane of single-crystalline tungsten dichalcogenide (WTe2), a group 6 metallic TMD. The WTe2 with a small amount of anionic (Te) vacancies shows an improved overpotential from –0.707 to –0.568 V and a constant Tafel slope of 154 mV/dec in the HER. Photoemission spectroscopy, combined with first-principle calculations, reveals that the work function of WTe2 is decreased by the anionic Te vacancies, which improves the bulk conductivity and the overpotential in the HER with the material. Moreover, the enlarged electrochemical active surface area with a large number of Te vacancies in the WTe2 critically improves the HER performance with decreases in the overpotential and the Tafel slope, –0.119 V and 79 mV/dec, respectively. Our results show that the modulation of work function and surface morphology is a promising way to improve the HER in TMDs.
KW - Anion vacancy
KW - Hydrogen evolution reaction
KW - Transition metal dichalcogenides
KW - WTe
KW - Work function
UR - http://www.scopus.com/inward/record.url?scp=85081137098&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2020.145972
DO - 10.1016/j.apsusc.2020.145972
M3 - Article
AN - SCOPUS:85081137098
SN - 0169-4332
VL - 515
JO - Applied Surface Science
JF - Applied Surface Science
M1 - 145972
ER -