Here we report the effect of microwave treatment on a silica–carbon (SiO2
/C) filler derived from rice husk and the function of the microwave‐treated filler in an epoxy matrix for electronic ...packaging applications. Thermogravimetric analysis revealed improved thermal stability of the SiO2
/C filler upon microwave treatment. X‐ray diffraction analysis indicated partial SiC formation after the microwave treatment. For packaging applications, compared to that of the pure epoxy polymer, the thermal conductivity of the epoxy–SiO2
/C composite was improved by 178% at 40 wt % content of the microwave‐treated SiO2
/C filler. Furthermore, an improvement of 149% in storage modulus and 17.6°C in glass transition temperature of the epoxy–SiO2
/C composites was realized. The improvement in thermal stability of SiO2
/C filler could be achieved via a simple microwave treatment, which in turn enhanced the thermal stability, thermal conduction, and thermomechanical strength of the electronic packaging materials.
Improvement in thermal stability of SiO2/C filler could be achieved via a microwave treatment, which in turn enhanced the thermal stability, thermal conduction, and thermomechanical strength of the electronic packaging materials.
•NbC/polyimide-derived graphene (PDG) composite has been prepared via laser scribing route.•The NbC decorated PDG show enhanced electric and thermal conductivities.•The NbC/PDG can be used as ...efficient heat sinks for industrial computers, LEDs and LIBs.•The photothermal properties of the NbC/PDG are also evaluated.
Thermal management and heat dissipation are universal challenges related to high-power systems. Graphene and its related composite materials exhibit the potential for widespread application as thermal management materials owing to their high thermal conductivity and emissivity. In this study, we synthesize polyimide (PI)-derived graphene (PDG) incorporated with NbC nanoparticles via CO2 laser scribing on Nb precursor-containing PI sheets. The resultant NbC-decorated PDG (NbC-PDG) shows improved thermal conductivity (0.70 W/m·K) compared with bare PDG (0.24 W/m·K). We use NbC-PDG as an efficient heat sink for industrial computers (ICs), light-emitting diode (LED) modules, and lithium-ion batteries (LIBs). The equilibrium temperature of the applications can be reduced significantly by the NbC-PDG layer owing to its excellent radiation heat transfer. After integration of the NbC-PDG heat sink, the equilibrium temperatures of the IC, LED module, and LIB decreased by 8.1, 9.9, and 7.3 °C, respectively. Accordingly, the performance, efficiency, and lifetime of optoelectronic and electrochemical systems can be enhanced considerably. The NbC-PDG composite with broadband absorption and excellent photothermal properties can be applied for efficient solar–thermal energy conversion. Additionally, we fabricate an NbC-PDG-deposited melamine sponge via spray coating and evaluate its performance in solar-driven desalination and water purification.
A coral-like carbon material (Coral-C) is synthesized by growing curled carbon nanotubes (CNTs) onto carbon black (Lamp Black) to incorporate the unique structures and properties of the two ...nanostructured carbons, CNTs and carbon spheres. This Coral-C, having a good electronic conductivity, is used as a supporting material for Pt nanocatalyst for application in fuel cell electrodes. The Pt nanoparticles, being synthesized by a ligand exchange method, are stabilized on Coral-C though an enhanced deposition process with poly(oxyproplyene)diamines. The Coral-C supported Pt catalyst shows excellent electrochemical active area (102.5 m2 g−1 Pt), good catalytic activity toward methanol oxidation (1.5 times higher than E-TEK Pt/C), and good power output in single DMFC (1.3 times better than E-TEK Pt/C), which could be attributed to the unique nanostructure of the catalyst: high conductivity of the surface accessible support and highly distributed Pt nanoparticles. The successful advancement in this coral-like nanostructure design for fuel cell catalyst presents a significant achievement in both the scientific and engineering fields.
A polyacrylonitrile (PAN)-interpenetrating cross-linked polyoxyethylene (PEO) network (named XANE) was synthesized acting as separator and as gel polymer electrolytes simultaneously. SEM images show ...that the surface of the XANE membrane is nonporous, comparing to the surface of the commercial separator to be porous. This property results in excellent electrolyte uptake amount (425 wt %), and electrolyte retention for XANE membrane, significantly higher than that of commercial separator (200 wt %). The DSC result indicates that the PEO crystallinity is deteriorated by the cross-linked process and was further degraded by the interpenetration of the PAN. The XANE membrane shows significantly higher ionic conductivity (1.06–8.21 mS cm–1) than that of the commercial Celgard M824 separator (0.45–0.90 mS cm–1) ascribed to the high electrolyte retention ability of XANE (from TGA), the deteriorated PEO crystallinity (from DSC) and the good compatibility between XANE and electrode (from measuring the interfacial-resistance). For battery application, under all charge/discharge rates (from 0.1 to 3 C), the specific half-cell capacities of the cell composed of the XANE membrane are all higher than those of the aforementioned commercial separator. More specifically, the cell composed of the XANE membrane has excellent cycling stability, that is, the half-cell composed of the XANE membrane still exhibited more than 97% columbic efficiency after 100 cycles at 1 C. The above-mentioned advantageous properties and performances of the XANE membrane allow it to act as both an ionic conductor as well as a separator, so as to work as separator-free gel polymer electrolytes.
Hollow Li2FeSiO4 spheres have been successfully prepared using hollow silica spheres as both reactant and template, for which the thickness of the nanoscale Li2FeSiO4 thin shells are about 50 nm. ...Then, the hollow Li2FeSiO4 spheres were coated by phenolic resin as a carbon precursor to obtain the hollow Li2FeSiO4/Carbon sphere (HLFS/C) composite. The structure characterizations by X-ray diffraction, transmission electron microscopy and scanning electron microscopy show that the HLFS/Cs are hollow structures with high purity. When used as the cathode material under charge/discharge rates at 0.05C (1C = 166 mAh g−1), the HLFS/C exhibited a capacity of 155 mAh g−1 with good cycle stability. Furthermore, the HLFS exhibited capacities of 820, 650 and 420 mAh g−1 for 0.15C, 0.3C and 0.6C rates for anode application, respectively, with good cycle stability. The hollow structure of HLFS/C enables us to overcome the aggregation and structural instability problems, which is essential for the improvement of the electrochemical performance.
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•Hollow Li2FeSiO4 spheres (HLFS) have been successfully prepared.•The HLFS were coated by carbon to obtain the hollow HLFS/C sphere composite.•The HLFS exhibited capacities of 820 mAh g−1 for 0.15C rates for anode application.
A thin layer of LiFePO4 was coated onto a mesoporous carbon sphere to obtain a mesoporous core–shell LiFePO4/carbon sphere (LFP/MCS) composite, for which the thickness of the nanoscale LiFePO4 thin ...shell was approximately 30–50 nm. Meanwhile, pristine LFP and MCS mixed with LFP samples (MCS‐m‐LFP) were prepared for comparison. The significantly larger surface area of LFP/MCS (43–151 m2 g−1) compared with pristine LFP (12 m2 g−1) is derived from the mesoporous carbon framework and thin nanoscale LFP shell. The large surface area of LFP/MCS provides greater surface content between the LiFePO4 shell and electrolytes, which results in a high charge–discharge rate. Also, this remarkably thin LiFePO4 cathode shell shortens the diffusion length of lithium ions thereby achieving a high charge–discharge rate for electrode materials. Consequently, under all charge–discharge rates (0.1–20 C), the specific capacities of LFP/MCS are higher than those of both the pristine LFP and MCS‐m‐LFP. More specifically, at 10 C, LFP/MCS exhibited the excellent rate performance of 82 mAh g−1, compared to 25 and 41 mAh g−1 for LFP and MCS‐m‐LFP, respectively. Furthermore, the discharge capacity for LFP/MCS at the high discharge rate of 20 C remains stable whereas that for LFP does not. This demonstrates the efficient transport capability of Li ions into the nanoscale LFP shell in the core–shell structure of LFP/MCS, which is essential for the improvement of the electrochemical performance.
Looking beyond the surface: A thin layer of LiFePO4 is coated onto a mesoporous carbon sphere to obtain a mesoporous core–shell LiFePO4/carbon sphere (LFP/MCS) composite. The large surface area of LFP/MCS provides greater surface content between the LiFePO4 shell and electrolytes, which results in a high charge–discharge rate.
► An exceptionally durable and highly active Pt catalyst has been prepared by embedding Pt nanoparticles inside the pores of a nitrogen-doped porous carbon layer coated on carbon nanotubes. ► In the ...accelerated durability test, the
I
max after 2000 cycles for Pt@NC-CNT-600 decreased from 13.2 to 6.9
mA
cm
−2 (48% decreased) compared with Pt/XC-72, which showed a decrease from 10.8 to 0.46
mA
cm
−2 (96% decreased). ► Pt@NC-CNT's superior durability properties were further verified by observing the changes of the Pt particle sizes using TEM images before and after accelerated durability tests, as compared with Pt/XC-72.
An exceptionally durable and highly active Pt catalyst has been prepared by embedding Pt nanoparticles inside the pores of a nitrogen-doped porous carbon layer coated on carbon nanotubes (denoted as Pt@NC-CNT). The aforementioned material, under different carbonization temperatures, is characterized by transmission electron microscopy, N
2 adsorption and desorption isotherms, X-ray photoelectron spectroscopy, and Raman spectroscopy. The maximum current density (
I
max) during the methanol oxidation reaction (MOR) observed for Pt@NC-CNT (13.2
mA
cm
−1) is 20% higher than that of the commercial Pt/XC-72 (10.8
mA
cm
−1) catalyst. In the accelerated durability test, the
I
max after 2000 cycles for Pt@NC-CNT-600 decreased from 13.2 to 6.9
mA
cm
−2 (48% decreased) compared with Pt/XC-72, which showed a decrease from 10.8 to 0.46
mA
cm
−2 (96% decreased). This indicates that the Pt@NC-CNT catalyst has extremely stable electrocatalytic activity for MOR owing to its unique structure, whereby Pt is protected by being embedded inside the pores of the nitrogen-doped carbon layer. Pt@NC-CNT's superior durability properties are further verified by observing the changes of the Pt particle sizes using TEM images before and after accelerated durability tests, as compared with Pt/XC-72.
Correction for 'Green synthesis of nitrogen-doped multiporous carbons for oxygen reduction reaction using water-caltrop shells and eggshell waste' by Chun-Han Hsu
et al.
,
RSC Adv.
, 2021,
11
, ...15738-15747. DOI:
10.1039/D1RA02100A
.
A thermally reduced graphene oxide (TRGO) grown with carbon nanotubes composite (G-CNT) was utilized as three-dimensional highly conductive carbon scaffolds, where a large amount of small and ...homogeneous Pt nanoparticles (from 3.37 ± 1.22 to 4.24 ± 1.83 nm) was directly synthesized on G-CNT to acquire a new type of catalyst (Pt/G-CNT). Meanwhile, Pt nanoparticles loaded on TRGO (Pt/TRGO) and on TRGO blended with carbon nanotubes (Pt/G-b-CNT) were prepared for comparison. The G-CNT showed a very high electrical conductivity (144.4 S cm−1) compared to the G-b-CNT (67.5 S cm−1) and TRGO (9.1 S cm−1). In contrast to Pt/G-b-CNT (36.8 m2 g−1) and Pt/TRGO (28.1 m2 g−1), Pt/G-CNT showed a very high electrochemically active surface area (77.4 m2 g−1). As these catalysts were utilized as the anode for the fuel cell, the maximum power density value for Pt/G-CNT (32.0 mW cm−2) was about 65% and 74% higher than that of Pt/G-b-CNT (19.4 mW cm−2) and Pt/TRGO (18.4 mW cm−2), respectively, and 26% higher than that of E-TEK (25.4 mW cm−2).
► A thermally reduced graphene oxide grown with CNT composite (G-CNT) was utilized as 3D highly conductive carbon scaffolds. ► The maximum current density for Pt/G-CNT was 23% higher than that of the commercial catalyst (E-TEK). ► The maximum power density value for Pt/G-CNT was 26% higher than that of E-TEK.
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