ABSTRACT
This study describes the single-step synthesis of a mesoporous layered nickel-chromium-sulfide (NCS) and its hybridization with single-layered graphene oxide (GO) using a facile, inexpensive chemical method. The conductive GO plays a critical role in improving the physicochemical and electrochemical properties of hybridized NCS/reduced GO (NCSG) materials. The optimized mesoporous nanohybrid NCSG is obtained when hybridized with 20% GO, and this material exhibits a very high specific surface area of 685.84 m2/g compared to 149.37 m2/g for bare NCS, and the pore diameters are 15.81 and 13.85 nm, respectively. The three-fold superior specific capacity of this optimal NCSG (1932 C/g) is demonstrated over NCS (676 C/g) at a current density of 2 A/g. A fabricated hybrid supercapacitor (HSC) reveals a maximum specific capacity of 224 C/g at a 5 A/g current density. The HSC reached an outstanding energy density of 105 Wh/kg with a maximum power density of 11,250 W/kg. A 4% decrement was observed during the cyclic stability study of the HSC over 5000 successive charge-discharge cycles at a 10 A/g current density. These results suggest that the prepared nanohybrid NCSG is an excellent cathode material for gaining a high energy density in an HSC.
ABSTRACT
This study demonstrates a novel application of laser-induced graphene (LIG) as a reusable conductive particulate matter (PM) filter. Four types of LIG-based filters were fabricated based on the laser-induced pyrolysis of thin polyimide (PI) sheets, each pyrolyzed on either a single side or both sides, with or without densification. The LIG filters exhibited a high removal efficiency while maintaining minimal pressure drop compared to a commercial fiberglass filter. The densified LIG (dLIG) filters displayed a higher PM2.5 removal efficiency (>99.86%) than regular LIG filters. The dLIG filters also exhibited excellent durability when tested for washability by ultrasonication in tap water. After being cleaned and left to dry, the structures of the dLIG filters were well-maintained; their filtration efficiencies were also well-maintained (less than a 7% change in PM2.5 removal efficiency), and their resistances only marginally increased (less than a 7% increase after five uses). These results demonstrate the robustness and reusability of the dLIG filters and the accessibility of their cleaning (not requiring aggressive cleaning agents). These promising features will enable the application of LIG in economical, scalable, and high-performance air cleaning.
ABSTRACT
This study demonstrates a simple strategy to fabricate Co3O4 on N-doped laser-induced graphene (Co3O4-NLIG) based on duplicate laser pyrolysis, enabling the in situ generation of Co3O4 nanoparticles and heteroatom doping in laser-induced graphene (LIG). Morphological analyses reveal the uniform distribution of Co3O4 nanoparticles on the surface of the LIG structure. The modification of NLIG with Co3O4 nanoparticles results in impressive electrochemical performance due to the contributions from electric double-layer capacitance and pseudocapacitance. The optimal Co3O4-NLIG is produced at 20 wt% cobalt precursor loading (Co3O4-NLIG-20). In a three-electrode setup, this electrode exhibits a specific areal capacitance (C A) of 216.3 mF cm-2 at a current density of 0.5 mA cm-2 in a 1 M KOH electrolyte. When the optimal electrodes are assembled into a solid-state supercapacitor (Co3O4-NLIG-SC) using a poly(vinyl alcohol) phosphoric acid (PVA-H3PO4) gel electrolyte, a C A of 17.96 mF cm-2 is obtained with good cycling stability.
