1T-Phase Transition Metal Dichalcogenides (MoS₂, MoSe₂, WS₂, and WSe₂) with Fast Heterogeneous Electron Transfer: Application on Second-Generation Enzyme-Based Biosensor

Abstract

Two-dimensional transition metal dichalcogenides (TMDs) have been in the spotlight for their intriguing properties, including a tunable band gap and fast heterogeneous electron-transfer (HET) rate. Understandably, they are especially attractive in the field of electrochemical biosensors. In this article, HET capabilities of various TMDs (MoS, MoSe, WS, and WSe) within group VI chemically exfoliated via t-BuLi intercalation are studied and these capabilities are used in the second generation electrochemical glucose biosensor. Strikingly, tungsten dichalcogenides (WS and WSe) exhibit superior HET properties compared to that of their molybdenum counterparts (MoS and MoSe). When incorporated into second generation glucose biosensors, WS and WSe generated a higher electrochemical responses than that of MoS and MoSe, following the same trend as expected. The commendable performance by WX is attributed to the dominance of 1T phase, revealed by characterization data. The developed and optimized 1T WX-based biosensor achieved analytical requirements of selectivity, wide linear ranges, as well as low limits of detection and quantification. The outstanding electrochemical performances of WS and WSe are to be recognized, adding on to the fact that they are not decorated with any metal nanoparticles. This is imperative to showcase the real potential of two-dimensional TMDs in electrochemical biosensors.

Composition dependence of the charge-driven phase transition in group-VI transition metal dichalcogenides

“…They are prevented from transitioning immediately back to the ground-state H phase by an energy barrier. This is supported by the observation of the M 4+ oxidation state in X-ray photoelectron spectra (XPS) 24,25,57 .…”

“…Yet, compared to other group-VI TMDs, the phase transition efficiency in MoS 2 can be relatively low: a comprehensive side-by-side comparison of the experimental transition efficiency in four group-VI TMDs -MoS 2 , MoSe 2 , WS 2 and WSe 2found that WS 2 exhibited the largest increase in the proportion of the 1T phase compared to the starting 2H phase (i.e., the 1T/2H ratio), followed by MoSe 2 and WSe 2 , and eventually MoS 2 . 24 While the exact ratios were subsequently found to depend on the nature of the organolithium intercalant group used in the experiment, the general trend remained: WX 2 compounds display a higher proportion of T phase compared to MoX 2 , for both X = S and Se 25,26 .…”

Strong Charge Transfer at 2H–1T Phase Boundary of MoS2 for Superb High‐Performance Energy Storage

“…It is affected by the parameters such as the sample size, chemical environment, and content of defects. [13,[22][23][24] To trace the kinetics of this phase transition in the MoS 2 /G nanohybrid film, we have measured the evolution of the XPS spectra of Mo 3d with the increase in annealing temperature (Figure 2a). The quantitative analysis of the phase change shows that the content of the 1T phase decreases almost linearly with increasing temperature up to about 150 °C (Figure 2b).…”

Enhanced Charge Transport via Metallic 1T Phase Transition Metal Dichalcogenides‐Mediated Hole Transport Layer Engineering for Perovskite Solar Cells

“…Structural quality of WSe 2 flake was investigated through X‐ray diffraction (XRD) analysis. As shown in Figure S1 is available online at, the distinctive (00 l ) at 13.6, 41.8, and 56.8°, represented as (002), (006), and (008), respectively, implies the c‐axis of hexagonal WSe 2 with well‐ordered crystal structure . The morphology of as‐exfoliated WSe 2 flakes was investigated by atomic force microscopy (AFM) as presented in Figure d.…”

“…As shown in Figure S1 is available online at, the distinctive (00 l) at 13.6, 41.8, and 56.8°, represented as (002), (006), and (008), respectively, implies the c-axis of hexagonal WSe 2 with well-ordered crystal structure. [30] The morphology of as-exfoliated WSe 2 flakes was investigated by atomic force microscopy (AFM) as presented in Figure 1d. The thickness of WSe 2 flakes ranged from 2.0-3.0 nm corresponding to a few layers in thickness.…”