Fast colloidal synthesis of scalable Mo-rich hierarchical ultrathin MoSe_2−xnanosheets for high-performance hydrogen evolution

Abstract

MoSe2 nanosheets have been extensively pursued due to the outstanding properties of this typical layered transition metal dichalcogenide (LTMD). In this work, we report a facile, fast strategy to synthesize scalable hierarchical ultrathin MoSe2-x (x ∼ 0.47) nanosheets. The nanosheets possess 2-5 Se-Mo-Se atomic layers and were synthesised through a bottom-up colloidal route within 20 mins under mild conditions from the reaction of MoO2(acac)2 with dibenzyl diselenide. The as-obtained hierarchical ultrathin MoSe2-x nanosheets are Mo-rich with a Se vacancy and show excellent HER performance with a small overpotential of ∼170 mV, large cathodic currents, and a Tafel slope of 98 mV per decade. Such high performance has been attributed to the unique structure of the Se vacancy defect, large surface area, as well as the enhanced conductivity. Meanwhile, the pathway can be extended as a general strategy to prepare other metal selenides, such as ultrathin WSe2 and SnSe nanosheets, and PbSe nanocrystals. It will also pave a new way to synthesize scalable nanostructured materials for intriguing nanodevices and large-scale applications.

One-pot synthesis of nanosheet-assembled hierarchical MoSe2/CoSe2 microcages for the enhanced performance of electrocatalytic hydrogen evolution

“…11, 49 The peaks of Co 2p 1/2 at 793.5 eV and Co 2p 3/2 at 778.5 eV (Fig. S1c †) indicate the presence of Co-Co, 78 which is commonly present in CoSe 2 with Co/Se/Co layered structure.…”

“…Therefore, the increase number of active sites by forming the nanosheets or nanoparticles with particular morphologies have been found to be an efficient pathway to enhance the HER activity. 8,13,28,31,43,44,49 However, with the introduction of the active edge sites the nanosized particles or sheets would intensively reduce the intrinsic electric conductivity of the catalysts, with a consequent degradation of the electrons transport during the catalytic process. [52][53][54] It is therefore critical to develop electrocatalysts with both active edges and good conductivity to achieve high HER performance.…”

“…13,50,60,61,74,75 Molybdenum chalcogenides is prone to evolve into a hierarchical structure composed of ultrathin nanosheets, 49 while cobalt chalcogenides tend to form simpler shapes such as nanobelt 76,77 or nanoparticles. These different structural congurations imply the existence of different crystallization kinetics in these two types of TMD composites synthesized via hydrothermal, solvothermal or colloidal methods.…”

Modelling the nucleation, growth and coarsening kinetics of γ″ (D022) precipitates in the Ni-base Alloy 625

“…48 The resulting MoS 2 structures are free from organic ligands, such as oleylamine, which would otherwise need to be removed prior to use in catalysis or energy storage applications. 37,49 UV-visible and photoluminescence (PL) spectroscopy of the samples are described in the Supporting Information, and demonstrate how the optical properties of the frustules can be controlled by the addition of the MoS 2 nanosheets. The unique photonic properties of diatom frustules, 18 in combination with the broadband absorption, good electron mobility, and tuneable band gap of MoS 2 (ranging from 1.2eV in the bulk to 1.8eV in monolayers), could also be exploited in optoelectronic devices.…”

A general method for ultrathin 1D oxide nanomaterials

“…Moreover, the ultrathin 1D nanostructures with size of 1-2 nm is rarely studied due to the lack of preparation methods for such materials. [7][8][9][10][11][12] In this work, we report a universal method through the construction of inorganic-surfactant mesostructures to synthesize such ultrathin 1D nanostructures, including transition metal oxides and rare earth oxides.…”