Site‐Selective Oxidation of Monolayered Liquid‐Exfoliated WS₂ by Shielding the Basal Plane through Adsorption of a Facial Amphiphile

Abstract

In recent years, various functionalization strategies for transition-metal dichalcogenides have been explored to tailor the properties of materials and to provide anchor points for the fabrication of hybrid structures. Herein, new insights into the role of the surfactant in functionalization reactions are described. Using the spontaneous reaction of WS 2 with chloroauric acid as a model reaction, the regioselective formation of gold nanoparticles on WS 2 is shown to be heavily dependent on the surfactant employed. A simple model is developed to explain the role of the chosen surfactant in this heterogeneous functionalization reaction. The surfactant coverage is identified as the crucial element that governs the dominant reaction pathway and therefore can severely alter the reaction outcome. This study shows the general importance of the surfactant choice and how detrimental or beneficial a certain surfactant can be to the desired functionalization.

Anti-corrosion MgO nanoparticle-equipped graphene oxide nanosheet for efficient room-temperature H2S removal

“…Furthermore, the S 2p high-resolution XPS spectra of MgO/rGO-S (Fig. 4g) reveal four peaks, namely S 2p 3/2 (164.0 eV) and S 2p 1/2 (165.2 eV) of elemental sulfur (S, 0 valence) peak, 59 and S 2p 3/2 (168.8 eV) and S 2p 1/2 (170.0 eV) of sulfate (S, +6 valence) peak, 60 with elemental sulfur and sulfate at 89.0% and 11.0% (Table S5†), respectively. For ZnO/rGO-S and Fe 2 O 3 /rGO-S (Fig.…”

Spontaneous Decoration of Ultrasmall Pt Nanoparticles on Size‐Separated MoS2 Nanosheets

“…Additives such as surfactants could impact the spontaneous metal decoration process, and even bring about site-selective reactivity to nanosheets. [18] Their absence on nanosheet surfaces in the present case provides an insight into intrinsic nanosheet reactivity. The exfoliated nanosheets have been characterized by various methods to determine both lateral dimensions, as well as thickness.…”

“…In this manner, size‐selected nanosheet dispersions of MoS 2 are obtained in water without the use of stabilizing additives. Additives such as surfactants could impact the spontaneous metal decoration process, and even bring about site‐selective reactivity to nanosheets [18] . Their absence on nanosheet surfaces in the present case provides an insight into intrinsic nanosheet reactivity.…”

Spontaneous formation of gold nanoparticles on MoS2 nanosheets and its impact on solution-processed optoelectronic devices

“…Upon obtaining dispersions with controlled and well-characterized nanosheet size, we carried out Au nanoparticle decoration through a spontaneous reduction of HAuCl 4 using MoS 2 . This reaction is enabled through a suitable alignment of the energy levels between MoS 2 and AuCl 4 − , which results in a spontaneous electron transfer ( Grieger et al., 2020 ; Kim et al., 2013 ; Polyakov et al., 2014 ; Song et al., 2018 ; Yuan et al., 2019 ). As also observed for other 2D materials, the reduction occurs preferably at defect sites owing to favorable energetics ( Lu et al., 2015 , 2018 ; Tao et al., 2021 ), and results in the growth of Au nanoparticles.…”

“…Direct addition of nanoparticles is another adopted route, although the process for first growing such nanoparticles forms a separate synthesis step and involves the use of reducing agents ( Pramanik et al., 2019 ). In this regard, transition metal dichalcogenides possess a rich chemistry, which enables them to reduce metal precursors such as HAuCl 4, resulting in Au nanoparticle decoration through solution-processable protocols ( Grieger et al., 2020 ; Kim et al., 2013 ; Polyakov et al., 2014 ). The spontaneity of this reduction reaction arises from the intrinsic chemical nature of the nanosheets and effectively bypasses the need for additional synthetic processes and associated use of chemicals.…”