General Colloidal Synthesis of Transition-Metal Disulfide Nanomaterials as Electrocatalysts for Hydrogen Evolution Reaction

Abstract

The material-efficient monolayers of transition-metal dichalcogenides (TMDs) are a promising class of ultrathin nanomaterials with properties ranging from insulating through semiconducting to metallic, opening a wide variety of their potential applications from catalysis and energy storage to optoelectronics, spintronics, and valleytronics. In particular, TMDs have a great potential as emerging inexpensive alternatives to noble metal-based catalysts in electrochemical hydrogen evolution. Herein, we report a straightforward, low-cost, and general colloidal synthesis of various 2D transition-metal disulfide nanomaterials, such as MoS 2 , WS 2 , NiS x , FeS x , and VS 2 , in the absence of organic ligands. This new preparation route provides many benefits including relatively mild reaction conditions, high reproducibility, high yields, easy upscaling, no post-thermal annealing/treatment steps to enhance the catalytic activity, and, finally, especially for molybdenum disulfide nanosheets, high activity in the hydrogen evolution reaction. To underline the universal application of the synthesis, we prepared mixed Co x Mo 1−x S 2 nanosheets in one step to optimize the catalytic activity of pure undoped MoS 2 , which resulted in an enhanced hydrogen evolution reaction performance characterized by onset potentials as low as 134 mV and small Tafel slopes of 55 mV/dec.

Untangling the Intertwined: Metallic to Semiconducting Phase Transition in Colloidal MoS2 Nanoplatelets and Nanosheets

“…14,15 On the one hand, the influence of edge states increases for small lateral sizes of 2D TMDC layers. While these states are found in the band gap and are essential for catalysis, [16][17][18][19] they also suppress photoluminescence (PL) by non-radiative recombination in the structures. 20 On the other hand, the wave functions of the electron and hole are affected by growing quantum confinement in 2D MoS 2 with decreasing lateral dimension.…”

Layer-Dependent Band Structure of Ternary Metal Chalcogenides: Thickness-Controlled Hexagonal FeIn2S4

“…When CS 2 is injected into the reaction under the presence of a primary amine, dithiocarbamate is formed followed by nucleophilic attack (Step 1 in Scheme S1). Then, with excess oleyl amine and thermal energy, a second amine molecule is added rapidly, leading to in situ release of H 2 S gas − (Step 2 in Scheme S1). When alkyl thiol is injected into the reaction in the presence of the primary amine, a bond between the metal cation and sulfur is formed following a deprotonation reaction at the SH group (Step 1 in Scheme S2).…”

2D Transition Metal Dichalcogenides‐Based Electrocatalysts for Hydrogen Evolution Reaction

“…Very recently, Meerbach et al. [ 183 ] has designed a general synthetic route to fabricate transition‐metal disulphide nanomaterials as electrocatalysts for HER. Precisely, the group has successfully synthesized different 2D materials without any organic ligand, e.g., VS 2 , NiS, FeS, and MoS 2 .…”

“…In order to enhance the maximum exposed active sites, compact size of the single layer nanosheet of 2D materials could enhance the specific surface area, which lead to the enhanced HER performances. Very recently, Meerbach et al [183] has designed a general synthetic route to fabricate transition-metal disulphide nanomaterials as electrocatalysts for HER. Precisely, the group has successfully synthesized different 2D materials without any organic ligand, e.g., VS 2 , NiS, FeS, and MoS 2 .…”