title: Electrochemical tuning of vertically aligned MoS2 nanofilms and its application in improving hydrogen evolution reaction.
abstract: The ability to intercalate guest species into the van der Waals gap of 2D layered materials affords the opportunity to engineer the electronic structures for a variety of applications. Here we demonstrate the continuous tuning of layer vertically aligned MoS2 nanofilms through electrochemical intercalation of Li(+) ions. By scanning the Li intercalation potential from high to low, we have gained control of multiple important material properties in a continuous manner, including tuning the oxidation state of Mo, the transition of semiconducting 2H to metallic 1T phase, and expanding the van der Waals gap until exfoliation. Using such nanofilms after different degree of Li intercalation, we show the significant improvement of the hydrogen evolution reaction activity. A strong correlation between such tunable material properties and hydrogen evolution reaction activity is established. This work provides an intriguing and effective approach on tuning electronic structures for optimizing the catalytic activity.
authors.affiliation: Departments of Applied Physics, Materials Science and Engineering, Mechanical Engineering, and Chemical Engineering, Stanford University, Stanford, CA 94305.
authors.forename: Haotian
authors.initials: H
authors.lastname: Wang
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Lu
authors.forename: Shicheng
authors.initials: S
authors.lastname: Xu
authors.forename: Desheng
authors.initials: D
authors.lastname: Kong
authors.forename: Judy J
authors.initials: JJ
authors.lastname: Cha
authors.forename: Guangyuan
authors.initials: G
authors.lastname: Zheng
authors.forename: Po-Chun
authors.initials: PC
authors.lastname: Hsu
authors.forename: Kai
authors.initials: K
authors.lastname: Yan
authors.forename: David
authors.initials: D
authors.lastname: Bradshaw
authors.forename: Fritz B
authors.initials: FB
authors.lastname: Prinz
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui
mesh_terms: D002384:Catalysis; D004220:Disulfides / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D006859:Hydrogen / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008982:Molybdenum / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*
chemical_list: D004220:Disulfides; D006859:Hydrogen; D008982:Molybdenum; C082964:molybdenum disulfide
keywords: 2D materials; electrochemical catalysis; layer vertically standing