title: All The Catalytic Active Sites of MoS2for Hydrogen Evolution.
abstract: MoS2presents a promising low-cost catalyst for the hydrogen evolution reaction (HER), but the understanding about its active sites has remained limited. Here we present an unambiguous study of the catalytic activities of all possible reaction sites of MoS2, including edge sites, sulfur vacancies, and grain boundaries. We demonstrate that, in addition to the well-known catalytically active edge sites, sulfur vacancies provide another major active site for the HER, while the catalytic activity of grain boundaries is much weaker. The intrinsic turnover frequencies (Tafel slopes) of the edge sites, sulfur vacancies, and grain boundaries are estimated to be 7.5 s-1(65-75 mV/dec), 3.2 s-1(65-85 mV/dec), and 0.1 s-1(120-160 mV/dec), respectively. We also demonstrate that the catalytic activity of sulfur vacancies strongly depends on the density of the vacancies and the local crystalline structure in proximity to the vacancies. Unlike edge sites, whose catalytic activity linearly depends on the length, sulfur vacancies show optimal catalytic activities when the vacancy density is in the range of 7-10%, and the number of sulfur vacancies in high crystalline quality MoS2is higher than that in low crystalline quality MoS2, which may be related with the proximity of different local crystalline structures to the vacancies.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Li
authors.forename: Du
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Qiao
authors.identifier: 0000-0002-0229-4407
authors.initials: Q
authors.lastname: Qiao
authors.forename: Yifei
authors.initials: Y
authors.lastname: Yu
authors.forename: David
authors.identifier: 0000-0002-4256-9866
authors.initials: D
authors.lastname: Peterson
authors.forename: Abdullah
authors.initials: A
authors.lastname: Zafar
authors.forename: Raj
authors.identifier: 0000-0003-4001-0011
authors.initials: R
authors.lastname: Kumar
authors.forename: Stefano
authors.initials: S
authors.lastname: Curtarolo
authors.forename: Frank
authors.initials: F
authors.lastname: Hunte
authors.forename: Steve
authors.initials: S
authors.lastname: Shannon
authors.affiliation: Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Yimei
authors.initials: Y
authors.lastname: Zhu
authors.forename: Weitao
authors.initials: W
authors.lastname: Yang
authors.forename: Linyou
authors.identifier: 0000-0002-7834-8336
authors.initials: L
authors.lastname: Cao