Growing Biomorphic Transition Metal Dichalcogenides and Their Alloys Toward High Permeable Membranes and Efficient Electrocatalysts Applications

3D architecratured transition metal dichalcogenides constructed by atomically thin layers are appealing building blocks in various applications,such as catalysts,energy storage,conversions,sensors,and so on.However,the direct growth of 3D transition metal dichalcogenides architectures with high crystal quality and well-controlled size/thickness remains a huge challenge.Herein,we report a facile,highly-repeatable,and versatile chemical vapor deposition strategy,for the mass production of high-quality 3D-architecratured transition metal dichalcogenides(e.g.,MoS_(2),WS_(2),and ReS_(2))and their alloys(e.g.,W_(x)Mo(1–x)S_(2)and Rex Mo_((1–x))S_(2))nanosheets on naturally abundant and low-cost diatomite templates.Particularly,the purified transition metal dichalcogenides products exhibit unique and designable 3D biomorphic hierarchical microstructures,controllable layer thicknesses,tailorable chemical compositions,and good crystallinities.The weak interlayer interactions endow them with good dispersity in solutions to form stable additive-free inks for solution-processing-based applications,for example,high-permeable and high-stable separation membranes for water purification,and efficient electrocatalysts for hydrogen evolution reactions.This work paves ways for the low-cost,mass production of versatile transition metal dichalcogenides powder-like materials with designable structures and properties,toward energy/environmental-related applications and beyond.

Space-confined growth of monolayer ReSe2 under a graphene layer on Au foils

Vertical heterostructures based on two-dimensional(2D)materials have attracted widespread interest for their numerous applications in electronic and optoelectronic devices.Herein,we report the direct construct!on of an abnormal graphene/ReSe2 stack on Au foils by a two-step chemical vapor deposition(CVD)strategy.During the second growth stage,mono layer ReSe2 is found to prefere ntially evolve at the irUerface between the first-grown graphene layer and the Au substrate.The unusual stacking behavior is unraveled by in-situ"cutting open"the upper graphene from the defects to expose the lower ReSe2 using scanning tunneling microscopy(STM).From combination of these results with density functional theory calculations,the domain boundaries and edge sites of graphene are proposed to be adsorption sites for Re and Se precursors,further facilitating the growth of ReSe2 at the van der Waals gap of graphene/Au.This work hereby offers an intriguing strategy for obtaining vertical 2D heterostructures featured with an ultra-clean interface and a designed stacking geometry.

Scalable salt-templated directed synthesis of high-quality MoS_(2) nanosheets powders towards energetic and environmental applications

Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have emerged as perfect platforms for developing applications in nano-electronics,catalysis,energy storage and environmental-related fields due to their superior properties.However,the low-cost,batch production of high-quality 2D TMDCs remains a huge challenge with the existing synthetic strategies.Herein,we present a scalable chemical vapor deposition(CVD)approach for the batch production of high-quality MoS_(2) nanosheet powders,by using naturally abundant,water-soluble and recyclable NaCl crystal powders as templates.The high-quality MoS_(2) nanosheets powders are achieved by a facile water dissolution-filtration process,by virtue of the excellent dispersibility of the as-grown products in water.The internal mechanism for the scalable synthesis strategy is explored.The applications of the MoS_(2) nanosheets powders are also demonstrated as catalysts or adsorbents in hydrogen evolution reaction(HER)and organic dyes adsorption,respectively.This work should hereby pave ways for the mass production and application of powdery TMDCs in energetic and environmental related fields.

Salt-assisted growth and ultrafast photocarrier dynamics of large-sized monolayer ReSe2

Owing to its anisotropic optical and electrical properties,rhenium diselenide(ReSe2)has garnered considerable attention recently as a candidate material for polarization-sensitive photodetectors.However,the direct and controllable synthesis of large-sized ReSe2 with a uniform thickness is still a great challenge.Herein,we have refined the synthesis method to obtain uniform monolayer ReSe2 flakes with a size of up to^106μm on sapphire via an ambient-pressure chemical vapor deposition technique using Na promoter from sodium chloride.Interestingly,optical pump-probe spectroscopy revealed a fast switching from saturable absorption(SA)to absorption enhancement(AE)in subpicosecond time scale,followed by a slower decay induced by exciton recombination.Furthermore,both AE and SA signals exhibited clear angular dependence with a periodicity of 180°,which reflected the dichroism in nonlinear absorption dynamics.In addition,the photocarrier dynamics including free-carrier transport and subpicosecond relaxation due to exciton formation or surface trapping was probed using time resolved terahertz spectroscopy.We believe that our study serves as a reference for atomically controlled synthesis of large-sized ReSe2 and provides useful insights on its optoelectronic properties for novel device applications.