Directly Exfoliated Ultrathin Silicon Nanosheets for Enhanced Photocatalytic Hydrogen Production

Abstract

Here we present direct exfoliation of ultrathin silicon nanosheets from commercial silicon powders through an improved liquid phase exfoliation procedure. The feasibility of exfoliation was ascribed to the intrinsic anisotropic lattice structure, which allowed the oriented propagations of cryo-mediation-induced quenching cracks with the assistance of sonication. It was also revealed that the solid–solvent interface played a critical role in determining the morphology of exfoliated pieces as well as the exfoliation efficiency. Moreover, due to its superior morphology, enlarged surface area, and improved photon absorption, the resulting ultrathin silicon nanosheets presented enhanced and visible light responsive photocatalytic hydrogen generation performance, even without applying any co-catalyst.

Impact of Pretreatment of the Bulk Starting Material on the Efficiency of Liquid Phase Exfoliation of WS2

“…This means that the lateral size of ML nanosheets will be intrinsically limited by the material’s binding strength and that the resultant aspect ratio will depend on the crystal structure. Note that this picture of LPE also explains why it is also possible to exfoliate non van der Waals crystals with anisotropic binding situation, as demonstrated recently for metal diborides [ 49 ], silicon [ 50 ] or germanium [ 51 ].…”

Liquid‐Phase Exfoliation of Nonlayered Non‐Van‐Der‐Waals Crystals into Nanoplatelets

“…In fact, as shear exfoliation is a relatively low energy process, [36] it is perhaps surprising that it can be used to exfoliate isotropic NL-NvdW materials at all. Certain crystals such β-B, [86][87][88][89][90]112,[115][116][117][118] FeS 2 , [79,82] Si, [73,78] and Ge [77,84] have been exfoliated by various research groups using multiple methods of LPE. This has resulted in different yields and dimensions of the exfoliated products as discussed in the next sections.…”

“…[79] Around the same time, silicon, a group 14 semiconductor with cubic crystal lattice structure was exfoliated using commercial sourced silicon powder. [78] TEM images showed the 2D-nature of the exfoliated product, and HRTEM showed lattice spacing of 0.19 nm, assigned to the (111) planes of the cubic crystal lattice structure of silicon. [78] We want to mention here that the first claims of silicon exfoliation were published in 2019 [73] but no structural analysis was done by the authors.…”

In Situ Cation Intercalation in the Interlayer of Tungsten Sulfide with Overlaying Layered Double Hydroxide in a 2D Heterostructure for Facile Electrochemical Redox Activity

“…Two-dimensional (2D) materials are currently hogging the limelight because of their unique chemistry, new structure–property function, large surface area that endows amenability toward top-down and bottom-up lithography methods, pliability and ability to be mechanically strained, and a wide range of applications. , A majority of the chemically synthesized nanosheets are stacked and/or agglomerated, and separating such 2D layers needs chemical exfoliation methods to increase the interlayer distance between the nanosheets . The interlayer interactions can be regulated by the intercalation of cations through controllable chemical reactions that can preserve ultrathin 2D crystalline nanosheets .…”

“…5,6 A majority of the chemically synthesized nanosheets are stacked and/or agglomerated, 7 and separating such 2D layers needs chemical exfoliation methods to increase the interlayer distance between the nanosheets. 6 The interlayer interactions can be regulated by the intercalation of cations through controllable chemical reactions that can preserve ultrathin 2D crystalline nanosheets. 8 Smaller cations like Li + and Na + are used as intercalating agents in energy storage devices where the insertion and extraction of these cations often lead to variations in the 2D interlayer spacing and successive phase transitions during the charge−discharge process.…”