Vertical Heterophase for Electrical, Electrochemical, and Mechanical Manipulations of Layered MoTe₂

Abstract

Phase engineering is a breakthrough for various electronic and energy device applications with transition metal dichalcogenides (TMDs). Chemical methods, such as lithium intercalation, are mostly used for phase engineering, which achieves atomically thin flakes and high catalytic performances in several group 6 TMDs including MoS 2 . However, chemical methods cannot be applied to MoTe 2 , a widely investigated group 6 TMD with intriguing semiconducting, topological, and catalytic properties. The lack of modifying MoTe 2 by chemical methods remains a puzzling issue considering the small energy difference between the polymorphs of MoTe 2 . Here, a convectionassisted lithium ion intercalation and phase transition is reported to achieve a vertical heterophase in a MoTe 2 crystal. The vertical heterophase in MoTe 2 reduces the Schottky barrier with metal electrodes down to 66 meV, enhancing the overall ion conductance for electrochemical hydrogen production. Moreover, the weakened adhesion of the 1T' phase layers on the top and bottom surfaces in the vertical heterophase, formed by the intercalation, enables a unique surface tension-driven exfoliation of MoTe 2 flakes. The heterophase chemical engineering suggests a new platform for hybrid catalysts and next-generation electronic devices based on 2D materials.

2D Transition Metal Dichalcogenides: Design, Modulation, and Challenges in Electrocatalysis

“…The first one is the chemical exfoliation process with organolithium compounds such as butyllithium (BuLi), [ 84–88 ] methyllithium (MeLi), [ 89 ] or lithium borohydride (LiBH 4 ) [ 87 ] ( Figure a–c). In this method, bulk TMDs powder would be soaked into the solution, containing the lithium sources and corresponding organic solvent (such as hexanes), and continuous ultrasonication (usually more than 2 days) would be synchronously applied to make the exfoliation more efficient.…”

Bilayer MoSe2/HfS2 Nanocomposite as a Potential Visible-Light-Driven Z-Scheme Photocatalyst

“…In order to set up a sustainable society, photocatalytic water splitting for hydrogen production has been deemed as an effective route to solve the problems of environmental pollution and energy shortage [1]. Owing to the groundbreaking work by Honda and Fujishima in 1972 [2], a variety of semiconductor materials have been extensively investigated to explore high-performance photocatalysts for water decomposition [3][4][5][6][7]. However, a majority of one-component photocatalysts, such as TiO 2 and ZnO, can only utilize a small amount of the solar energy and the lifetimes of photoinduced electron-hole pairs in these materials are short, which leads to the problem that the photocatalytic efficiency is low and hampers their future applications [8,9].…”

Metallic Transition Metal Dichalcogenides of Group VIB: Preparation, Stabilization, and Energy Applications

“…Moreover, the induction methods are also alternative controllable strategies to obtain metallic TMDs by the means of triggering transition from the 2H phase counterparts. The inducer could be the introduction of foreign species (such as alkali ions intercalations [78][79][80][81][82] ), the extra energy supplying (external irradiation methods [83][84][85][86][87] ) or the additional applied force (strain methods [88][89][90] ). Herein, several common preparation strategies of metallic group VIB TMDs have been discussed in this part, the merits and deficiencies of those approaches are also briefly compared as listed in Table 1 and 2.…”