Production of monolayer-rich gold-decorated 2H–WS2 nanosheets by defect engineering

Abstract

Chemical functionalization of low-dimensional nanostructures has evolved as powerful tool to tailor the materials' properties on demand. For two-dimensional transition metal dichalcogenides, functionalization strategies are mostly limited to the metallic 1T-polytype with only few examples showing a successful derivatization of the semiconducting 2H-polytype. Here, we describe that liquid-exfoliated WS 2 undergoes a spontaneous redox reaction with AuCl 3 . We propose that thiol groups at edges and defects sites reduce the AuCl 3 to Au 0 and are in turn oxidized to disulfides. As a result of the reaction, Au nanoparticles nucleate predominantly at edges with tuneable nanoparticle size and density. The drastic changes in nanosheet mass obtained after high loading with Au nanoparticles can be exploited to enrich the dispersions in laterally large, monolayered nanosheets by simple centrifugation. The optical properties (for example photoluminescence) of the monolayers remain pristine, while the electrocatalytic activity towards the hydrogen evolution reaction is significantly improved.

Class-selective voltammetric determination of hydroxycinnamic acids structural analogs using a WS2/catechin-capped AuNPs/carbon black–based nanocomposite sensor

“…with AuNPs has been attempted using different strategies (auto assembling exploiting gold thiophilicity, electrodeposition, etc.) [8,12,25], the decoration of WS2 with AuNPs has been explored in lesser extension [13,14] particularly for the development of sensors [15]. In this work, the WS2 decoration was attempted using AuNPs synthesized using catechin (AuNPs-CT), sodium citrate and sodium borohydride as mild reducing agent following the strategy of section 2.3.2 (schematized in Scheme S1).…”

“…Nevertheless, TMDs have demonstrated to be elective building blocks for the development of hybrids nanomaterials, giving rise to improved and sometimes unexpected properties [8][9][10][11]. However, despite metal nanostructure-decorated MoS2 nanocomposites, have been extensively studied [8], the use of WS2 has been little explored [13,14] particularly in the sensors field [15].…”

Tailoring the physicochemical properties of solution-processed transition metal dichalcogenides via molecular approaches

“…In fact, NPs can interact with both liquid-phase exfoliated and ce-TMDs via covalent 133 and non-covalent 127 interactions, resulting in hybrid systems characterized by exceptional performances for (photo)catalysis 134,135 and biomedicine 131,136 applications. The growth of NPs takes place after the reduction of a noble metal precursor salt, 17 due to an addition of reducing agent 137 or spontaneous formation.…”

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

“…Dispersions of nanomaterials are particularly suitable for functionalization owing to the efficiency and versatility of wet chemical methods, yet the reaction mechanisms for these heterogeneous reactions leading to functionalization are often not well understood. For example, a surprising regioselectivity was found in the recently reported spontaneous redox reaction of LPE WS 2 with chloroauric acid, which resulted in the formation of covalently bound nanoparticles to edges of the nanosheets . By controlling the reaction conditions, it was possible to remove heavy mass aggregates of Au@WS 2 to isolate predominantly monolayers in high yield with small (2–4 nm) Au nanoparticles at edges.…”