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The electrochemical performance of mechanically spheroidized natural and synthetic graphite particles is significantly influenced by the type of spheroidization process used and the applied conditions. In order to guarantee a consistent and high material quality, spherical graphite particles have to be carefully benchmarked before use. Three spherical natural graphites and three spheroidized synthetic...
Carbon nanotubes (CNTs) were chemically modified to achieve strong binding strength with the attached functional components as well as good dispersability and nanoparticle size-uniformity. An efficient multi-oxidation process was developed to create porous out layer with many nanoscale defects on the surface of CNTs for metallic nanoparticle close attachment and bond sufficient oxygen-containing groups,...
In this study, the analysis of the mechanical response of realistic fullerene-nanotube nanotruss networks with face-centered cubic geometry is performed by using molecular dynamics with reactive potentials. In particular, the mechanical properties of these novel architectures are investigated in both compressive and tensile regimes, a number of truss geometries by straining along different directions...
The effects of nitrogen and oxygen atomic co-functionalization of graphite felt (GF) by ammoxidation reactions for the positive and negative electrodes of vanadium redox flow battery (VRFB) are investigated. Ammoxidative surface reactions of the pristine-GF with NH3/O2 results in effective N and O co-doping dominantly with kinetically relevant N and O functional groups; pyrrolic-N, pyridinic-N, and...
In this paper, phosphomolybdic acid H3PMo12O40 (PMo12) was anchored to four synthetic micro-mesoporous carbons and a commercial one to analyse the relationship between the porous texture of the support, the PMo12 adsorption and the performance of the resulting hybrid materials as electrodes in supercapacitors. The uptake of PMo12 on carbon supports follows a clear correlation with the micropore volume,...
We developed a method of precise isotope labeling to visualize the continuous growth of graphene by chemical vapour deposition (CVD). This method allows us to observe, as a function of time, the growth of graphene monocrystals at a resolution of a few seconds. This technique is used to extract the anisotropic growth rates, as well as investigate the formation of dendrites, and the dependence of growth...
Low-pressure chemical vapor deposition of graphene has been investigated on various Pt substrates such as e-beam deposited films, sputtered films, and polycrystalline foils. High temperature sputtering is found to be crucial in growing single layer graphene on Pt. It gives highly (111)-oriented crystallization with a significant reduction of dewetting in Pt films, in contrast to e-beam deposited Pt...
A detailed scanning tunneling microscopic (STM) investigation is carried out to directly image and understand the mechanism behind enhanced conductivity and electron field emission (EFE) properties for platinum (Pt) ion doped/post-annealed ultrananocrystalline diamond (UNCD) films. Straight imaging of conducting/non-conducting sites is mapped by dynamic scanning tunneling microscopy (D–STM). Energy...
Many experiments have shown that electrical conductivity and dielectric permittivity of graphene-polymer nanocomposites are strongly dependent on the loading frequency, but at present no theory seems to be able to address the continuous influence of frequency. In this work we present a new effective-medium theory that is derived from the underlying physical processes including the effects of filler...
The amorphous carbon derived from a “molten salt CO2 capture and electrochemical transformation” process, was characterized and studied for the adsorption of aqueous solutes. XRF and TG measurements showed that the electrolytic carbon (E-carbon) had a higher purity than the commonly available biochars and activated carbons due to its unique growth mechanism in molten salts. The analysis on morphology,...
Structural properties of sixteen (16) commercial samples of graphene-based materials (GBM) labelled as graphene, graphene oxide or reduced graphene oxide are investigated at room temperature using X-ray diffraction (XRD) and Raman spectroscopy. Based on the observed correlation between the results obtained with these two techniques, these samples are classified into three groups: Group A of seven...
Amorphous carbon (a-C) films co-doped by two metals exhibit a desirable combination of mechanical and tribological properties for wider applications. Nevertheless, the structural evolution of metal co-doped a-C films from the atomic and electronic scales is a critical pre-requisite to illustrate the intrinsic mechanism of residual stress reduction. Herein, we first fabricated the Ti/Al co-doped a-C...
Fine particulate matter (PM 2.5) is the principal instigators of adverse health events, yet gaps still remain in understanding the mechanism mediating its toxic response. Similar to nanoparticles, PM 2.5, with large surface area to volume ratio, can absorb multipollutants in air, displaying toxicity profiles that are very different from those of coarse particles of the same composition. One particularly...
Photoluminescence (PL) spectra of boron-doped diamonds at temperature 298 K were recorded with excitation in wavelength range 110–300 nm from a synchrotron source. A prominent emission feature was measured at 480.0 nm, corresponding to energy 2.535 eV; we detected also a distinct photoluminescence excitation (PLE) band at 220.5 nm, 5.623 eV, for the first time. For sensitive analysis, the UV-PL technique...
Even when not functionalized intentionally, most carbon materials are not hydrophobic and readily adsorb water molecules from atmospheric water vapor. We have equilibrated an ultramicroporous carbon at several levels of relative humidity, thereby attaining various hydration levels. The water molecules were adsorbed on the pore walls (but did not fill completely the pore volume) and thus could be better...
Strategies to synthesize reduced graphene oxide (rGO) abound but, in most studies, research teams select one particular oxidation-reduction method without providing a methodic reasoning for doing so. Herein, it is analyzed how diverse oxidation-reduction strategies commonly used can result in considerable performance differences of rGO for supercapacitor applications. Depending on the graphite oxidation...
A novel strategy for the synthesis of hierarchical porous carbons (HPCs) from interpenetrating polymer networks (IPNs) for advanced supercapacitor electrodes was reported. There is hydrogen-bonding interaction between resorcinol/formaldehyde (R/F) resol and zinc tartrate, and they were introduced into the inter space of sodium polyacrylate (PAAS) to form IPNs. HPCs with foam-like macropores, uniform...
In spite of high mean transfer number and catalytic ability of the oxygen reduction reaction (ORR), α-MnO2 is lack of electric conductivity and specific surface area to fully exert the performance of rechargeable Zn-air battery. Here, carbons in various forms are chosen as substrates for uniform dispersion of α-MnO2 to form air electrode catalysts to evaluate the influences of carbon types on the...
The ultrathin porous carbon shell with the thickness of about 10 nm has been fabricated by a facile method using sodium citrate as carbon precursor without any activation. The electric conductivity of the material is as high as 7.12 S/cm, which contributes to a good rate performance for supercapacitor electrode without any conductive additive. When tested in 6 M KOH by three-electrode system, the...
Lithium inventory loss is the most important reason for capacity decay of commercial lithium ion batteries. To suppress lithium inventory loss and prolong the battery cycle-life, sodium maleate (SM) is coated onto the surface of graphite active materials and act as the starting material for in-situ growth of SEI film. Microscopic studies show that the SM salt is uniformly dispersed on the graphite...
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