Rapid Preparation and Electrochemical Energy Storage Applications of Silicon Carbide and Silicon Oxycarbide Ceramic/Carbon Nanocomposites Derived Via Flash Photothermal Pyrolysis of Organosilicon Preceramic Polymers

Abstract

Silicon carbide (SiC) and silicon oxycarbide (SiOC) ceramic/carbon (C) nanocomposites are prepared via photothermal pyrolysis of cross-linked polycarbosilanes and polysiloxanes using a high-intensity pulsed xenon flash lamp in air at room temperature to yield crystalline and amorphous phases of SiC and SiOC ceramics, graphitic, and amorphous carbon phases. The millisecond duration of the radiation pulse is shorter than the thermal equilibrium time of the preceramic polymers (PCPs), enabling pyrolysis of the precursor phase and crystallization of the product before significant energy transfer to the substrate, making this process uniquely amenable to ceramic processing on or adjacent to thermally sensitive materials. Rapid precursor pyrolysis and product crystallization during flash lamp processing, even in air, limit oxidation of the resulting ceramics. To prepare the nanocomposites, PCPs are coated onto woven carbon fiber fabrics, thermally cross-linked, and then flash-lamp-pyrolyzed. The resulting nanocomposites are thermally and oxidatively stable at extremely high temperatures. The nanocomposites exhibit excellent performance as supercapacitor electrodes with capacitance as high as 27.2 mF/cm2 at a 10 mV/s scan rate at room temperature, excellent stability over 1000 cycles, and Coulombic efficiency of 80%. Patterned nanocomposites are prepared via nanoimprint lithography, followed by photothermal processing of precursor films. These nanocomposites have potential applications in energy storage, catalysis, and separations.

Rapid Synthesis of Patterned Silicon Carbide Coatings Using Laser‐Induced Pyrolysis and Crystallization of Polycarbosilane

“…Peaks corresponding to SiO at 101.7 eV and SiOC 3 at 103.3 eV are also inferred after deconvolution. [ 23 ] Note that oxide phase in the LISiC can be reduced by scanning the laser under inert atmosphere. Figure S3, Supporting Information, shows the XRD of LISiC synthesized after lasing with nitrogen flow (inert environment) instead of air flow.…”

“…Wang et al [ 22 ] sandwiched a 3D‐printed PCP structure between two Joule‐heating carbon paper strips that quickly heated samples to high temperatures (3000 °C) under inert environment and sintered them via heat radiation and conduction. Okoroanyanwu et al [ 23 ] used a high‐intensity pulsed light from a Xenon flash lamp for photothermal pyrolysis of cured PCP films and evaluated the resulting ceramic‐carbon composites as electrodes for supercapacitors.…”

Effect of pendant groups on the mass yield and density of polycarbosilanes during pyrolysis

“…The increased allylic group concentration and the added presence of methyl groups also contribute to a significantly higher concentration of excess carbon in the pyrolyzed SMP-877 samples relative to the SMP-10 samples. 28 The difference in the excess carbon observed at 1200 • C is likely established by 800 • C, as there is little mass loss at temperatures above that for both preceramic polymers (Figure 4). Specifically for SMP-10, the material density is relatively insensitive to time at a temperature between 800 and 1200 • C, 3 thus its slope is effectively a function of temperature.…”

Adsorption of anionic polyelectrolyte on an SiC surface and effects on dispersion stability

“…Silicon carbide (SiC) is an advanced ceramic with excellent integrated performance, such as high hardness and strength, high fracture toughness, superior thermal and chemical stability, and great thermal shock resistance 1–5 . Based on the previously mentioned characteristics, SiC ceramics have a broad application potential in the fields of nuclear, metallurgy, aerospace, catalysis, energy, and automobiles 6–9 . Some common defects, including inhomogeneous microstructure and pores in ceramic body, can deteriorate the mechanical properties of SiC ceramics 10,11 .…”

“…[1][2][3][4][5] Based on the previously mentioned characteristics, SiC ceramics have a broad application potential in the fields of nuclear, metallurgy, aerospace, catalysis, energy, and automobiles. [6][7][8][9] Some common defects, including inhomogeneous microstructure and pores in ceramic body, can deteriorate the mechanical properties of SiC ceramics. 10,11 High-concentrated SiC slurry with great stability and rheological behavior is the key for some forming processes to prepare dense green body with homogeneous microstructure.…”