Search results for "graphe"

3D defective graphenes with subnanometric porosity obtained by soft-templating following zeolite procedures

2019

[EN] By applying the well-known templating mechanism employed for the synthesis of mesoporous silicas to the structuration of sodium alginate, a novel defective 3D tubular graphene material (graphenolite) with hierarchical macro/meso/micro-porous structure, very high powder specific surface area (1820 m(2) g(-1)) and regular micropore size (0.6 nm) has been obtained. The key feature of the process is the filmogenic property of alginate that is able to replicate the liquid crystal rods formed by the CTAC template in the aqueous phase. The 3D graphene exhibits 2.5 times higher capacitance using Li+ electrolyte compared to K+, indicating that Li+ can ingress to the ultramicropores which, in co…

Electrophoretic Nanocrystalline Graphene Film Electrode for Lithium Ion Battery

2015

Graphene sheets were fabricated by electrophoretic deposition method from water suspension of graphene oxide followed by thermal reduction. The formation of nanocrystalline graphene sheets has been confirmed by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The electrochemical performance of graphene sheets as anode material for lithium ion batteries was evaluated by cycling voltammetry, galvanostatic charge-discharge cycling, and electrochemical impedance spectroscopy. Fabricated graphene sheets exhibited high discharge capacity of about 1120 mAhg−1 and demonstrated good reversibility of lithium intercalation and deintercalation in graphene sheet film with capacity…

Technical Program

2015

Electrical and Magnetic Properties of Graphene Films with Ni Nanoparticles

2015

Electrical properties and magnetic properties of graphene oxide and reduced graphene oxide films with addition of Ni nanoparticles were investigated. It is found that reduction of GO by Hydrazine hydrate (HH) and subsequent mixing with Ni NPs yields a higher current (10(-5)A) compared to the samples where GO is first mixed with Ni NPs and further reduced (10(-6)A). At the same time, GO sample prepared by addition of Ni NPs to GO with subsequent reduction by HH presents the largest hysteresis with Mr as high as 11.8emu/g. Moreover, mixing of Ni NPs with HH before addition to GO or addition of Ni NPs to already reduced GO yields smaller values of the magnetization. Thus, the optimal procedure…

The synthesis of a hybrid graphene–nickel/manganese mixed oxide and its performance in lithium-ion batteries

2012

Abstract Mixing of aqueous suspensions of delaminated NiMn layered double hydroxide (LDH) and graphene oxide leads to the instantaneous precipitation of a hybrid material that after calcination under inert atmosphere at 450 °C leads to Ni6MnO8 nanoparticles deposited on larger reconstituted graphene sheets. This material exhibits electrical conductivity similar to graphite, superparamagnetism and can be used as an anode for Li-ion batteries. A maximum capacity value of 1030 mA h g−1 was found during the first discharge, and capacity values higher than 400 mA h g−1 were still achieved after 10 cycles. The methodology used here should allow the preparation of a large variety of hybrid graphen…

Layer-by-Layer Graphene Growth on β-SiC/Si(001)

2019

ACS nano 13(1), 526 - 535 (2019). doi:10.1021/acsnano.8b07237

Synthesis of graphene oxide-intercalated α-hydroxides by metathesis and their decomposition to graphene/metal oxide composites

2010

Graphene oxide-intercalated alpha-metal hydroxides were prepared using layers from the delaminated colloidal dispersions of cetyltrimethylammonium-intercalated graphene oxide and dodecylsulfate-intercalated alpha-hydroxide of nickel/cobalt as precursors. The reaction of the two dispersions leads to de-intercalation of the interlayer ions from both the layered solids and the intercalation of the negatively charged graphene oxide sheets between the positively charged layers of the alpha-hydroxide. Thermal decomposition of the intercalated solids yields graphene/nanocrystalline metal oxide composites. Electron microscopy analysis of the composites indicates that the nanoparticles are intercala…

Facile hybridization of Ni@Fe2O3 superparticles with functionalized reduced graphene oxide and its application as anode material in lithium-ion batte…

2015

Abstract In our present work we developed a novel graphene wrapping approach of Ni@Fe2O3 superparticles, which can be extended as a concept approach for other nanomaterials as well. It uses sulfonated reduced graphene oxide, but avoids thermal treatments and use of toxic agents like hydrazine for its reduction. The modification of graphene oxide is achieved by the introduction of sulfate groups accompanied with reduction and elimination reactions, due to the treatment with oleum. The successful wrapping of nanoparticles is proven by energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy and Raman spectroscopy. The developed composite material shows strongly i…

How surface tension matters in polymer-free graphene transfer

2020

Abstract The main goal of this work is to achieve a direct transfer of graphene and examine the exact effect of surface tension (ST) on graphene during this type of transfer. To reach this target, we designed a specific transfer container with two-sided ports to facilitate replacing liquids underneath graphene and monitor the effect of ST. We prepared liquids with various STs by mixing pure deionized-water with different ratios of isopropanol (IPA). Our results indicate that high ST does not break the graphene structure if graphene has good quality. Besides, a ST gap (STG) can be applied to graphene at a specific level without damaging the graphene monolayer. Comparing those results to the …

Investigation of electron transfer between single plasmon and graphene by dark field spectroscopy

2020

Abstract We investigated the electron transfer time between single plasmonic gold nanoparticles and graphene with our home-build spectral imaging dark-field microscope. The process of electron transfer is supposed to be shuttling of hot electrons on the nanoparticle-graphene interface, resulting in a slight broadening of the scattering spectrum. For detecting the minor spectrum broadening, we firstly characterized our setup systematically and then calibrated its intrinsic error. We found the mechanism of a common but normally neglected setup error, scattering spectrum broadening, which is caused by the bandwidth of the incident light and could exist in most fast dark-field microscopy setups…