Molten salt synthesis of porous carbon and its application in supercapacitors: A review

Carbon materials have taken an important role in supercapacitor applications due to their outstanding features of large surface area,low price,and stable physicochemical properties.Considerable research efforts have been devoted to the development of novel synthesis strategy for the preparation of porous carbon materials in recent years.In particular,molten salt strategy represents an emerging and promising method,whereby it has shown great potential in achieving tailored production of porous carbon.It has been proved that the molten salt-assisted production of carbon via the direct carbonization of carbonaceous precursors is an effective approach.Furthermore,with the incorporation of electrochemical technology,molten salt synthesis of porous carbon has become flexible and diversiform.Here,this review focuses on the mainstream molten salt synthesis strategies for the production of porous carbon materials,which includes direct molten salt carbonization process,capture and electrochemical conversion of CO_(2)to value-added carbon,electrochemical exfoliation of graphite to graphene-based materials,and electrochemical etching of carbides to new-type carbide-derived carbon materials.The reaction mechanisms and recent advances for these strategies are reviewed and discussed systematically.The morphological and structural properties and capacitive performances of the obtained carbon materials are summarized to reveal their appealing points for supercapacitor applications.Moreover,the opportunities and challenges of the molten salt synthesis strategy for the preparation of carbon materials are also discussed in this review to provide inspiration to the future researches.

A bioactive nanocomposite sponge for simultaneous hemostasis and antimicrobial therapy

Uncontrollable bleeding and bacterial infections are the major reasons for the high mortality of post-traumatic.In this study,a composite hemostatic chitosan sponge CaO_(2)@SiO_(2)/CS was prepared by combining a novel core-shell inorganic nano hemostatic CaO_(2)@SiO_(2)nanoparticles with carboxylated chitosan,which presents a multi-layered structure with a rough and hydrophilic surface for rapid absorption of blood.When the CaO_(2)@SiO_(2)nanoparticles in the CaO_(2)@SiO_(2)/CS come into contact with blood,the silanol group on its surface and the released H_(2)O_(2)and Ca2+can recruit and activate platelets,while generating fibrin clots and activating the endo-exogenous coagulation cascade reaction to achieve rapid clotting.The H_(2)O_(2)released from CaO_(2)@SiO_(2)shows the antimicrobial capacity and stimulates the production of tissue factors by endothelial cells.Meanwhile,the silica coating reduces the cytotoxicity of bare CaO_(2),thus reducing the risk of secondary bleeding at the site of vascular injury.CaO_(2)@SiO_(2)/CS(48 s)showed a 1.83-and 2.52-fold reduction in hemostasis time compared to commercial gelfoam and CS in a femoral artery hemorrhage model.This study illustrates the hemostatic mechanism of CaO_(2)@SiO_(2)and provides a reference for the development of clinical biomedical inorganic hemostatic materials.

Ultrasmall Fe-doped carbon dots nanozymes for photoenhanced antibacterial therapy and wound healing

Pathogenic bacteria pose a devastating threat to public health.However,because of the growing bacterial antibiotic resistance,there is an urgent need to develop alternative antibacterial strategies to the established antibiotics.Herein,iron-doped carbon dots(Fe-CDs,~3 nm)nanozymes with excellent photothermal conversion and photoenhanced enzyme-like properties are developed through a facile one-pot pyrolysis approach for synergistic efficient antibacterial therapy and wound healing.In particular,Fe doping endows CDs with photoenhanced peroxidase(POD)-like activity,which lead to the generation of heat and reactive oxygen species(ROS)for Gram-positive and Gram-negative bacteria killing.This study demonstrates Fe-CDs have significant wound healing efficiency of Fe-CDs by preventing infection,promoting fibroblast proliferation,angiogenesis,and collagen deposition.Furthermore,the ultrasmall size of Fe-CDs possesses good biocompatibility favoring clinical translation.We believe that the nanozyme-mediated therapeutic platform presented here is expected to show promising applications in antibacterial.

Graphene-enabled electrically controlled terahertz meta-lens

Metasurfaces have become a new photonic structure for providing potential applications to develop integrated devices with small thickness, because they can introduce an abrupt phase change by arrays of scatterers. To be applied more widely, active metasurface devices are highly desired. Here, a tunable terahertz meta-lens whose focal length is able to be electrically tuned by ～4.45λ is demonstrated experimentally. The lens consists of a metallic metasurface and a monolayer graphene. Due to the dependence of the abrupt phase change of the metasurface on the graphene chemical potential, which can be modulated using an applied gate voltage, the focal length is changed from 10.46 to 12.24 mm when the gate voltage increases from 0 to 2.0 V. Experimental results are in good agreement with the theoretical hypothesis. This type of electrically controlled meta-lens could widen the application of terahertz technology.

Weakened interlayer coupling in two-dimensional MoSe2 flakes with screw dislocations

The screw dislocations are intriguing defects that are often observed in natural and artificial materials. The dislocation spirals break the reflection and inversion symmetries of the lattices and modify the interlayer coupling in layer-structured materials, inducing additional complexity in layer stacking and thus novel properties in materials. Here, we report on the interlayer coupling of two-dimensional (2D) MoSe2 flakes with screw dislocations by atomic force microscopy (AFM), Raman spectra and photoluminescence (PL) spectra. By controlling the supersaturation conditions, 2D MoSe2 flakes with screw dislocations are grown on amorphous SiO2 substrates by chemical vapor deposition (CVD). AFM measurements reveal that the interlayer spacing in such 2D MoSe2 flakes with screw dislocation is slightly widened with respect to the normal AA- or AB-stacked ones due to the presence of the screw dislocations. Raman and PL spectra show that the interlayer coupling is weaker and thus the band gap is wider than that in the normal AA- or AB-stacked ones. Our work demonstrates that the interlayer coupling of 2D transition metal dichalcogenides (TMDCs) flakes can be tuned by the induction of screw dislocations, which is very helpful for developing novel catalysts and electronic devices.