Electrochemically exfoliated graphene as high-performance catalyst support to promote electrocatalytic oxidation of methanol on Pt catalysts

Electrochemically exfoliated graphene(EEG)is a kind of high-quality graphene with few oxygen-containing functional groups and defects on the surface,and thereby is more suitable as catalyst support than other carbon materials such as extensively used reduced graphene oxide(rGO).However,it is difficult to grow functional materials on EEG due to its inert surface.In this work,ultra-small Pt nanocrystals(~2.6 nm)are successfully formed on EEG and show better electrocatalytic activity towards methanol oxidation than Pt catalysts on r GO.The outstanding catalytic properties of Pt catalysts on EEG can be attributed to the fast electron transfer through EEG and high quality of Pt catalysts such as small grain size,high dispersibility and low oxidation ratio.In addition,SnO2 nanocrystals are controllably generated around Pt catalysts on EEG to raise the poison tolerance of Pt catalysts through using glycine as a linker.Owing to its outstanding properties such as high electrical conductivity and mechanical strength,EEG is expected to be widely used as a novel support for catalysts.

3D printing of high-performance micro-supercapacitors with patterned exfoliated graphene/carbon nanotube/silver nanowire electrodes

Micro-supercapacitors(MSCs)show great potential as on-chip energy storage devices for portable electronics.The major flaw of thin-film MSCs is their low energy density.To improve the energy density,thicker electrodes are required.However,the fabrication of MSCs with thick electrodes remains a challenge.In this work,a novel 3D printing method is employed to fabricate high-performance MSCs with interdigitated exfoliated graphene(EG)/carbon nanotube(CNT)/silver nanowire(Ag NW)electrodes.The nanowelding of Ag NW junction plays a critical role in the realization of 3D printing.To enhance the electrochemical performances of EG,phosphorus atoms are incorporated into the carbon framework with 1.7 at%.The areal capacitance of the 3D printed MSC is 21.6 mF cm^(-2)at a scan rate of 0.01 V s^(-1).The areal energy density of the MSC ranges from 0.5 to 2μWh cm^(-2)with a maximum power density of 2.5 mW cm^(-2).

A nanosilica/exfoliated graphene composite film-modified electrode for sensitive detection of methyl parathion

Graphene nanosheets （GS） were easily prepared through liquid-phase exfoliation of graphite powder in N,N-dimethylformamide （DMF） with the assistance of sodium citrate. Then, GS was coated onto a glassy carbon electrode （GCE） surface by drop to fabricate a GS]GCE nanointerface. Subsequently, by using tetraethylorthosilicate sol as precursor, nanosilica was electrochemically deposited onto the GS]GCE surface to produce a nanocomposite film electrode （nanosilicaJGSJGCE）. Electrochemical behaviors of methyl parathion （MP） on the nanosilica/GS/GCE surface were investigated thoroughly. It was found that the nanosilicaJGS nanocomposites can improve the redox peak currents of MP significantly due to the synergetic effect. The oxidation peak current was linearly related to MP concentration in the range from 0.0005 μmol/L to 5.6 μmol/L. The detection limit was calculated to be 0.07 nmol/L （SJN = 3）. The developed method was used to determine MP in real samples. The recoveries were in the range from 95.4% to 104.2%, demonstrating satisfactory results.

The Anti-Inflammatory Effects of NaCl with KCl as a Potent Graphene Exfoliator in a Patient with Guillaine-Barré Syndrome and Facial Nerve Palsy

Guillain-Barré syndrome is a rare but fatal autoimmune disease of unknown origin. Infectious disease is the most common etiology of Guillain-Barré syndrome. We had a 75-year-old female patient with Guillain-Barré syndrome and a 90-year-old male patient with facial nerve palsy admitted to our hospital. Both patients experienced recovery from early Guillain-Barré syndrome and peripheral facial nerve palsy after receiving intravenous infusion of NaCl with KCl solution and taking vitamin C.

Self-assembly of nitrogen-doped TiO2 with exposed {001} facets on a graphene scaffold as photo-active hybrid nanostructures for reduction of carbon dioxide to methane

Tailored synthesis of well-defined anatase TiO2-based crystals with exposed {001} facets has stimulated incessant research interest worldwide due to their scientific and technological importance. Herein, anatase nitrogen-doped TiO2 （N-TiO2） nanoparticles with exposed {001} facets deposited on the graphene （GR） sheets （N-TiO2-001/GR） were synthesized for the first time via a one-step solvothermal synthetic route using NH4F as the morphology-controlling agent. The experimental results exemplified that GR was uniformly covered with anatase N-TiO2 nanoparticles （10-17 nm）, exposing the {001} facets. The percentage of exposed {001} facets in the N-TiO2-001/GR nanocomposites was calculated to be ca. 35%. Also, a red shift in the absorption edge and a strong absorption in the visible light range were observed due to the formation of Ti-O-C bonds, resulting in the successful narrowing of the band gap from 3.23 to 2.9 eV. The photocatalytic activities of the as-prepared photocatalysts were evaluated for CO2 reduction to produce CH, in the presence of water vapor under ambient temperature and atmospheric pressure using a low-power 15 W energy-saving daylight lamp as the visible light source--in contrast to the most commonly employed high-power xenon lamps--which rendered the process economically and practically feasible. Among all the studied photocatalysts, the N-TiO2-001/GR nanocomposites exhibited the greatest CH4 yield of 3.70 p-mol＇gcatalyst 1, approxi- mately 11-fold higher activity than the TiO2-001. The enhancement of photocatalyfic performance was ascribed to the effective charge anti-recombination of graphene, high absorption of visible light region relative to the {101} facets. and high catalytic activity of {001} facets

Eco-friendly non-acid intercalation and exfoliation of graphite to graphene nanosheets in the binary-peroxidant system for EMI shielding

The development of the preparation strategy for high-quality and large-size graphene via eco-friendly routes is still a challenging issue.Herein,we have successfully developed a novel route to chemically exfoliate natural graphite into high-quality and large-size graphene in a binary-peroxidant system.This system is composed of urea peroxide(CO(NH_(2))_(2)·H_(2)O_(2))and hydrogen peroxide(H_(2)O_(2)),where CO(NH_(2))_(2)·H_(2)O_(2)is used in preparing graphene for the first time.Benefiting from the complete decomposition of CO(NH_(2))_(2)·H_(2)O_(2)and H_(2)O_(2)into gaseous species under microwave(MW)irradiation,no water-washing and effluent-treatment are needed in this chemical exfoliation procedure,thus the preparation of graphene in an eco-friendly way is realized.The resultant graphene behaves a large-size,high-quality and few-layer feature with a yield of~100%.Then 4µm-thick ultrathin graphene paper fabricated from the as-exfoliated graphene is used as an electromagnetic interference(EMI)shielding material.And its absolute effectiveness of EMI shielding(SSE/t)is up to 34,176.9 dB cm^(2)/g,which is,to the best of our knowledge,among the highest values so far reported for typical EMI shielding materials.The EMI shielding performance demonstrates a great application potential of graphene paper in meeting the ever-increasingly EMI shielding demands in miniaturized electronic devices.

Electrochemical synthesis and the functionalization of few layer graphene in ionic liquid and redox ionic liquid

Electrochemical reductive exfoliation of graphite to few layered graphene(FLG) in presence of 1-ethyl-2,3-dimethyl imidazolium bis(trifluoromethylsulfonyl) imide ionic liquid and redox ionic liquid based ferrocene has been investigated. Thus, by applying a mild negative potential(-2.7 V vs. Fc/Fc^+) to carbon electrode in ionic liquid graphene flakes could be generated. The generated materials have been characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, high resolution transmission electron microscopy and atomic force microscopy. XPS and Raman analysis show that the electrochemical reductive exfoliation provides the formation of FLG. The thickness of the resulting FLG was found to be ranged between 4 and1 nm. HR-TEM images reveal the formation of few graphene layers and in some cases single graphene layer was observed.Moreover, this electrochemical route conduces to the formation of ionic liquid functionalized FLG. Finally, the reductive exfoliation was further investigated in the presence of redox ionic liquid. XPS and electrochemical measurements confirm the presence of ferrocene.

2D materials via liquid exfoliation:a review on fabrication and applications

Since graphene was discovered, the study of two-dimensional(2D) materials with atomic thickness has become a hot spot. To prepare different 2D materials,different methods have been groped, such as mechanical exfoliation, chemical vapor deposition(CVD), liquid-phase exfoliation. This review mainly introduced the sonication liquid-phase exfoliation, an effective method to prepare 2D materials. Compared with mechanical exfoliation and CVD methods, liquid-phase exfoliation is convenient and costeffective and provides high yield. We focused on both theoretical and experimental details of this method. This method was reviewed according to the development of 2D materials from graphene, h-BN to transition metal chalcogenides(TMDs) and black phosphorus nanosheets.We discussed the applications of liquid-exfoliated 2D materials including micro- and nanoelectrical devices,photoelectric devices, and energy storage devices.