Fabrication of Two‐Dimensional Lateral Heterostructures of WS₂/WO₃⋅H₂O Through Selective Oxidation of Monolayer WS₂

Abstract

Two-dimensional (2D) lateral heterostructures have emerged as a hot topic in the fast evolving field of advanced functional materials , but their fabrication is challenging. The layer-structured WS2 was theoretically demonstrated to be inert to oxidation except for the monolayer, which can be selectively oxidized owing to the simultaneous interaction of oxygen with both sides. Combined with the theoretical calculations, a new method was developed for the successful construction of 2D lateral heterostructures of WS2 /WO3 ⋅H2 O in an ambient environment, based on a simple liquid-phase solution exfoliation. These lateral heterostructures of WS2 /WO3 ⋅H2 O have interesting properties, as indicated by enhanced photocatalytic activity toward the degradation of methyl orange (MO).

Enhanced Photocatalytic Activity of WS2 Film by Laser Drilling to Produce Porous WS2/WO3 Heterostructure

“…The XPS spectrum of a laser-treated sample is shown in Fig. 4d, where peaks located at 32.16 and 34.37 eV belong to W 4f 7/2 and W 4f 5/2 peaks of the atoms in +4 form, and relatively high energies of 35.74 and 37.75 eV originate from W 4f 5/2 and W 4f 7/2 peaks of the W atoms in +6 oxidation state, all of which are in agreement with previously reported WO 3 values 20, 46 . These results altogether reveal that the laser-treated sample contained two compositions of chemical compounds (WS 2 with W 4+ and WO 3 with W 6+ ).…”

“…The valence band after laser treatment increased, which is probably due to the partial oxidation of WS 2 into WO 3 created by laser treatment. WO 3 has a band gap of 2.5–2.8 eV, of which the potential at the valence band maximum versus the reversible hydrogen electrode (RHE) is larger than that of WS 2 20, 55 . The approximate band structure and charge transfer of WS 2 /WO 3 heterostructure is presented in Fig.…”

“…Visible-light responding WO 3 /WS 2 heterojunctions have been developed by hydrothermal/gas phase reaction 16 , in-situ anodic oxidation 17 , spray pyrolysis/sulfurization 18 , sputtering/plasma sulfurization 19 , and have exhibited both high optical absorption coefficients and catalytic activity. Compared against bulk WS 2 , the lateral heterostructure of WS 2 /WO 3 is capable of much greater degradation of methyl orange and higher photocurrent response 20 . The slow decrease in photocurrent observed on the WS 2 /WO 3 composite when the light was switched off reflects the favorable recombination properties of electron/hole pairs in the heterojunction 21 .…”

Interfacing 2D Semiconductors with Functional Oxides: Fundamentals, Properties, and Applications

“…Research on other transition-metal dichalcogenide (TMD) materials, such as MoSe2 and WS2, has shown similar properties. Currently, most reports are focused on MoS2, and thereby we mainly discuss MoS2 in this review [27][28][29].…”

Facile Preparation of Multifunctional WS2/WOxNanodots for Chelator-Free89Zr-Labeling and In Vivo PET Imaging

“…[15] In a few latest studies, MoS 2 and WS 2 dots were prepared by high-powered ultrasonication or high temperature hydrothermal processes, [15a, 15b, 16] during which the Mo (W) edge on the surface of the Mo(W)S 2 nanosheets were slightly oxidized. [15a, 17] In this work, we for the first time report that the synthesized WS 2 /WO x nanodots could function as inherent hard oxygen donors for stable radiolabeling of 89 Zr, which has a relatively long decay half-life (t 1/2 = 78.4 h) and a low positron energy (β + avg = 395.5 keV) particularly suitable for long-term tracking with PET imaging. [18] Those WS 2 /WO x nanodots with uniform ultra-small sizes but varied oxidation levels are prepared through solution treatment of WS 2 nanoflakes synthesized by a bottom-up method.…”