Design and Synthetic Scheme of Water Dispersible Graphene Oxide-Coumarin Complex for Ultra-Sensitive Fluorescence Based Detection of Copper (Cu2+) Ion in Aqueous Environment

Copper oxides and its salts are now widely used as pesticides to control fungal and bacterial diseases of field crops. Copper toxicity is often a major contributor of human health problems caused through accumulation of excess copper ions in various organs via drinking water, fruits and vegetables. So, detection and estimation of cupric ions in biological organs, drinking water, fruits and vegetables are extremely important. Recently, a fluorescence based sensor using coumarin dye (high quantum yield) has been proposed to detect micromolar Cu++ ion in biological organs. But major problem with coumarin dye is that it is insoluble in water and undergoes dye-dye aggregation in organic solvents. We proposed here a synthetic scheme of preparation of graphene oxide conjugated coumarin dye derivative which would be water dispersible and expected to be an ideal candidate for Cu2+ ion estimation in biological organs and drinking water.

Synthesis and Characterization of a Novel Graphene Oxide/titanium Dioxide Solvent-free Nanofluid

A novel graphene oxide/titanium dioxide（GO/TiO2） solvent-free nanofluid was firstly synthesized by employing GO, which was in-situ deposited by TiO2 as the core and（3-Glycidyloxypropyl） trime thoxysilane（KH560） and polyetheramine-M2070 as the shell. The morphology and structure of GO/TiO2 nanofluid were verified by Transmission electron microscopy（TEM）, X-ray diffraction（XRD） analysis, Fourier transform infrared spectroscopy（FTIR）, X-ray photoelectron spectroscopy（XPS） and UV-vis absorption spectra. These studies confirmed that TiO2 has been deposited onto GO with good dispersion, and the organic shell has been grafted onto the core successfully. Thermo gravimetric analysis（TGA） and viscosity analysis indicated that this nanoparticle hybrid material presented a liquid state without solvent at room temperature, and has great fluidity and thermal stability. The solubility investigation of GO/TiO2 nanofluid revealed its excellent amphiphilicity and the potential as the functional nanocomposites.

Heat Transfer Performance of a Multi-heat Pipe Using Graphene Oxide/Water Nanofluid

A multi-heat pipe is a device for heat transmission. It is composed of a heating section, a cooling section and an adiabatic section. The heating and cooling sections are the same and both are connected by four circular parallel tubes. This experimental study is performed to investigate heat transfer performance of a multi-heat pipe in the vertical orientation using pure water and GO （graphene oxide）/water nanofluid. GO/water nanofluids were synthesized by the modified Hummers method with 0.05%, 0.1%, 0.15%, and 0.2% volume concentrations. The thermal performance has been investigated with varying heat flux in the range of 10-30 W and 100% fill charge ratio. Wall temperature, thermal resistance, and heat transfer coefficient of the heat pipe are measured and compared with those for the heat pipe using pure water. The experimental results show that the evaporator wall temperature with GO nanofluid is lower than that of the base fluid. Also, the heat pipe that charged with nanofluids showed lower thermal resistance compared with pure water. Heat transfer enhancement is caused by suspended nanoparticles and is pronounced with the increase in particle volume fraction.

Radiative Blood-Based Hybrid Copper-Graphene Nanoliquid Flows along a Source-Heated Leaning Cylinder

Variant graphene,graphene oxides(GO),and graphene nanoplatelets(GNP)dispersed in blood-based copper(Cu)nanoliquids over a leaning permeable cylinder are the focus of this study.These forms of graphene are highly beneficial in the biological and medical fields for cancer therapy,anti-infection measures,and drug delivery.The non-Newtonian Sutterby(blood-based)hybrid nanoliquid flows are generalized within the context of the Tiwari-Das model to simulate the effects of radiation and heating sources.The governing partial differential equations are reformulated into a nonlinear set of ordinary differential equations using similar transformational expressions.These equations are then transformed into boundary value problems through a shooting technique,followed by the implementation of the bvp4c tool in MATLAB.The influences of various parameters on the model’s nondimensional velocity and temperature profiles,reduced skin friction,and reduced Nusselt number are presented for detailed discussions.The results indicated that Cu-GNP/blood and Cu-GO/blood hybrid nanofluids exhibit the lowest and highest velocity distributions,respectively,for increased nanoparticles volume fraction,curvature parameter,Sutterby fluid parameter,Hartmann number,and wall permeability parameter.Conversely,opposite trends are observed for the temperature distribution for all considered parameters,except the mixed convection parameter.Increases in the reduced skin friction magnitude and the reduced Nusselt number with higher values of graphene/GO/GNP nanoparticle volume fraction are also reported.Finally,GNP is identified as the superior heat conductor,with an average increase of approximately 5%and a peak of 7.8%in the reduced Nusselt number compared to graphene and GO nanoparticles in the Cu/blood nanofluids.

Removal of rubidium from brine by an integrated film of sulfonated polysulfone/graphene/potassium copper ferricyanide

A novel integrated film of sulfonated polysulfone/graphene/potassium copper ferricyanide(KCuFC/SPSG)was used for selectively extracting rubidium ion(Rb^(+))from brine.To form KCuFC/SPSG,the precursor film of sulfonated polysulfone/graphene(SPSG)was synthesized by phase conversion process,which was alternately immersed in 0.1 mol·L^(-1)CuSO_(4)/K_(4)[Fe(CN)_(6)]by in-situ adsorption coupled co-precipitation method.Various data such as nuclear magnetic resonance spectrometer,Fourier transform infrared spectroscope,X-ray photoelectron spectroscope,X-ray diffraction,scanning electron microscope,and energy dispersive spectroscopy all verified that abundant KCuFC were uniformly located on the film.The resulting KCuFC/SPSG was used in film separation system.As the solution was fed into the system,the Rb^(+)could be selectively adsorption by KCuFC/SPSG.After the saturation adsorption,0.5 mol·L^(-1)NH_(4)Cl/HCl was fed into the film cell,Rb^(+)could be quickly desorbed by ion-exchange between Rb^(+)and NH_(4)^(+)in the lattice of KCuFC.The purpose of separating and recovering Rb^(+)from the brine can be achieved after the repeated operation.The effects of pH,adsorption time,and interferential ions on the adsorption capacity of Rb^(+)were investigated by batch experiments.The adsorption behavior fits the pseudo-second order kinetic process,while KCuFC has a higher adsorption capacity(Langmuir maximum sorption 165.4 mg·g^(-1)).In addition,KCuFC/SPSG shows excellent selectivity for Rb^(+)even in complex brine systems.KCuFC/SPSG could maintain 93.5%extraction efficiency after five adsorption/desorption cycles.

Unsteady MHD Casson Nanofluid Flow Past an Exponentially Accelerated Vertical Plate:An Analytical Strategy

In this study,the characteristics of heat transfer on an unsteady magnetohydrodynamic(MHD)Casson nanofluid over an exponentially accelerated vertical porous plate with rotating effects were investigated.The flow was driven by the combined effects of the magnetic field,heat radiation,heat source/sink and chemical reaction.Copper oxide(CuO)and titanium oxide(TiO2)are acknowledged as nanoparticle materials.The nondimensional governing equations were subjected to the Laplace transformation technique to derive closed-form solutions.Graphical representations are provided to analyze how changes in physical parameters,such as the magnetic field,heat radiation,heat source/sink and chemical reaction,affect the velocity,temperature and concentration profiles.The computed values of skin friction,heat and mass transfer rates at the surface were tabulated for various sets of input parameters.It is perceived that there is a drop in temperature due to the rise in the heat source/sink and the Prandtl number.It should be noted that a boost in the thermal radiation parameter prompts an increase in temperature.An increase in the Prandtl number,heat source/sink parameter,time and a decrease in the thermal radiation parameter result in an increase in theNusselt number.The computed values of the skin friction,heat andmass transfer rates at the surface were tabulated for various values of the flow parameters.The present results were compared with those of previously published studies andwere found to be in excellent agreement.This research has practical applications in areas such as drug delivery,thermal medicine and cancer treatment.

Fluorescent graphene oxide derived from carbonized citric acid for copper(Ⅱ) ions detection

Fluorescent graphene oxide(GO) nanoparticles were obtained from the thermal carbonization of citrate acid.Depending on the synthesizing temperature,the size of GO varied from several to several hundred nanometers.Owing to the confinement from the size,green and blue emissions at around 504 and 450 nm were observed from the GO suspension.These emissions could be dynamically quenched by titrating against copper(Ⅱ)(Cu^(2+)) ions,and the emission intensity was reduced exponentially as a function of Cu^(2+)concentration.The quenching mechanism was ascribed to the bridging of the surface-COOH andOH groups by Cu^(2+),which restricted the vibration of edge atoms or clusters and reduced the number of luminophores of GO nanosheets.As a result,the concentration of Cu^(2+)was detectable with the fluorescent intensity of GO.

A 2D Layer Copper(Ⅱ) Coordination Polymer with 3-Nitrophthalic Acid: Synthesis, Crystal Structure and Copper 3-Nitrophthalate Metal-organic Framework-graphene Oxide Nanocomposite

A 2D layer Cu(Ⅱ) coordination polymer [Cu(npth)(H_(2)O)]n(1) was crystallized from a mixture of 3-nitrophthalic acid and Cu(OAc)_(2)·H_(2)O in water under room temperature and structurally characterized by single-crystal X-ray diffraction, FT-IR and TGA. Compound 1 was applied to make a nanocomposite with graphene oxide(GO). A highly dispersible and stable nanocomposite of Cu(npth)-GO was successfully synthesized by a simple ultrasonication method. SEM, TEM, UV-vis, FT-IR and TGA were used to characterize the morphology and structure of the prepared composite. In accordance with the characterization results, we suspected that the binding mechanism of Cu(npth) and GO was assigned to be the cooperative interaction of Cu–O coordination, π-π stacking and hydrogen bonding.

Graphene Nanosheets Decorated with Copper Oxide Nanoparticles for the Photodegradation of Methylene Blue

Textile industries extensively use colorants,such as methylene blue,and if disposed off untreated,they contaminate the effluent streams,causing a severe impact on the environment and aquatic life.Photocatalytic degradation has been found as an inevitable approach to treat them.Herein,we decorated the copper oxide nanoparticles on graphene nanosheets during the reflux process.The resultant copper oxide/graphene nanocomposites were analyzed for structural and functional attributes.It was observed that on increasing the copper oxide contents,the z-average size of the resultant nanocomposites decreased.The X-ray diffraction analysis demonstrated the crystalline nature of the nanocomposite.The surface morphology of the copper oxide nanoparticles appeared to be spherical and that of the copper oxide/graphene composite somehow wrinkled.The infrared analysis indicated successful intercalation of precursors in the nanocomposite.The bandgap of copper oxide/graphene nanocomposites varied in the range of 1.03—1.30 eV,which indicated their effective photocatalytic activity.The results demonstrated that after 120 min of exposure,the methylene blue removal efficiency reached 94.0%,92.2%,and 89.4%(mass fraction)on the copper oxide/graphene nanocomposite at copper oxide nanoparticles to graphene nanosheets ratios of 1:1,1.5:1,and 2:1(mass ratio),respectively.The photodegradation performance of the prepared nano-catalyst was found satisfactory even after five cycles.

Diffusive transport of two charge equivalent and structurally similar ruthenium complex ions through graphene oxide membranes

Here, we report a study of ion transport across graphene oxide （GO） membranes of various thicknesses, made by vacuum filtration of GO aqueous solutions. The diffusive transport rates of two charge-equivalent ruthenium complex ions Ru（bpy）3^2＋ and Ru（phen）32% with a sub-angstrom size difference, are distinguishable through GO membranes and their ratio can be a unique tool for probing the transport-relevant pore structures. Pore and slit-dominant hindered diffusion models are presented and correlated to experimental results. Our analysis suggests that ion transport is mostly facilitated by large pores （larger than 1.75 nm in diameter） in the relatively thin GO membranes, while slits formed by GO stacking （less than 1.42 nm in width） become dominant only in thick membranes. By grafting PEG molecules to the lateral plane of GO sheets, membranes with enlarged interlayer spacing were engineered, which showed drastically increased ion transport rates and lower distinction among the two ruthenium complex ions, consistent with the prediction by the slit-dominant steric hindered diffusion model.

Investigation of Platinum Dispersed on Reduced Graphene Oxide-supported Tungsten Carbide via Sacrificial Cu Adlayers for Methanol Oxidation

Reduced graphene oxide-supported tungsten carbide composite(WC/RGO)was prepared by program-con-trolled reduction-carburization technique.Scanning electron microscope(SEM)and transmission electron micro-scope(TEM)show that WC nanoparticles with a narrow distribution(10-20 nm)are highly dispersed both on the edge and between the layers of RGO.And then it was used as a support to load different low contents(no more than 0.4 wt%)of Pt via sacrificial Cu adlayers.The morphology and the electrocatalytic activity of the prepared catalysts were characterized by TEM and cyclic voltammograms(CV),respectively.The results indicate that a small amount of isolated Pt atoms show low or even no activity for methanol oxidation.With the increasing deposition cycles,the content of Pt and the ensembles of neighboring Pt atoms are increased,which makes the onset potential shift nega-tively and mass current density increase.The results demonstrate that controllable amount of Pt can be deposited on WC/RGO by galvanic displacement with Cu,and the extent and domain of Pt loading affect the electrochemical performance.Meanwhile,this research also provides another route to prepare a catalyst with ultra low noble metal on WC/RGO for solving the problem of high cost of the catalyst.

一步电沉积法制备铜表面稀土镧/石墨烯超疏水复合涂层及其耐腐蚀性能

海洋腐蚀的倾向性是制约铜基材料使用性能和安全性的一个重要因素。因此,提高铜表面耐腐蚀能力成为研究重点。采用一步快速电沉积工艺在铜基表面制备肉豆蔻酸镧/氧化石墨烯(LaM/GO)超疏水复合涂层,采用扫描电镜(SEM)、X射线光电子能谱仪(XPS)、水接触角测量和电化学测试等手段对复合涂层的结构及性能进行了表征。结果表明:电沉积阴极表面产生了低表面能材料和花瓣状微纳粗糙结构,涂层表面静态水接触角为154°±3°,滚动角为5°±3°;电位动态极化曲线测量表明,超疏水复合涂层表面的腐蚀电位增加、腐蚀电流密度降低了2个数量级,缓蚀效率达99.34%,耐腐蚀性能得到显著提升;此外,所获得超疏水复合涂层表面显示出优异的防污性能和机械稳定性。

基于功能化荧光氧化石墨烯的CuNCs标记生物传感器对癌胚抗原检测的价值研究

构建基于功能化荧光氧化石墨烯(graphene oxide,GO)的荧光铜纳米簇(Fluorescent copper nanoclusters,CuNCs)标记生物传感器的荧光分析法,用于灵敏检测癌胚抗原(Carcinoembryonic antigen,CEA),分析荧光猝灭效率与CEA浓度的相关性。适配体寡核苷酸探针(aptamer)与CEA特异性结合,形成CEA-aptamer-GO-CuNCs复合物,随着CEA浓度的增加,CuNCs的荧光强度能够被有效淬灭,绘制CEA浓度与荧光猝灭效率标准曲线,通过测定待测样本的荧光猝灭效率而定量CEA浓度。本次研究建立了检测CEA的aptamer-GO-CuNCs标记生物传感器的荧光分析法,最佳孵育时间为15 min,孵育温度为37℃,CuSO4溶液最佳浓度为300μmol/L,线性范围为0.05~50ng/mL,检出限(S/N=3)为0.01ng/mL。本荧光分析法可准确检测人血清样本中CEA浓度,且检测灵敏、特异性均较好,可为临床上癌症早期临床筛查、诊断以及治疗、预后评估等提供指导。

PC/铜负载氧化石墨烯复合材料的抗菌性能

聚碳酸酯(PC)是一种具有优异综合性能的工程塑料,在抗菌产品的应用中,改进PC材料的短效抗菌性能和耐洗刷性能,可提高其抗菌效率和使用寿命。通过液相混合和喷雾干燥工艺,在不同氧化石墨烯(GO)和硫酸铜添加比例条件下,合成了三种铜负载氧化石墨烯抗菌剂(Cu@GO)。随后,将抗菌剂与PC进行混合和注塑,制备了一系列PC/铜负载氧化石墨烯复合材料(PC/Cu@GO)。测试了三种PC/Cu@GO复合材料的常规抗菌性能、高效抗菌性能和耐洗刷性能。结果表明,Cu@GO抗菌剂能够显著提升PC的抗菌性能,当GO与硫酸铜添加比为1∶9时,对应PC的短时间抗菌性能优异,接种6h,其对大肠杆菌和金黄葡萄球菌的抗菌率为96.8%和70.0%。当GO与硫酸铜质量比为1∶3时,经洗刷后PC的抗菌耐久性较好,经过4次洗刷和浸泡处理后,其对大肠杆菌和金黄葡萄球菌的抗菌率仍保持在68.2%和61.7%。

多孔氧化铜/石墨烯的制备及其光催化苯羟基化的研究

作为一种重要的化工原料,苯酚在工业领域的应用非常广泛。但传统的苯酚制备方法较为复杂且不利于环保,一步法光催化苯制苯酚则具有制备方法简单、绿色环保的优点,引起了研究者的广泛关注。本文以硝酸铜和石墨烯为原料,采用水热法和自组装技术制备了结合紧密的CuO/GO纳米复合材料。通过SEM、TEM、BET、XRD等手段对CuO/GO纳米复合材料进行了表征,研究了其在光催化苯羟基化反应中的催化性能,考察了催化剂加量、反应时间、苯的加量、氧化剂的用量等反应条件对催化剂的催化性能的影响,以及催化剂的回收重复利用率。结果表明,当苯含量为4mL、n(H_(2)O_(2))/n(苯)为7.5、CuO/GO的加量为0.328g·L^(-1)时,光反应2h,苯的转化率为52.8%,苯酚的产率为28.4%,且该光催化材料在重复使用后仍具有良好的催化性能。

氧化石墨烯负载氧化铈对铜基复合材料性能的影响

为了提高铜基复合材料的综合性能,本试验设计了三种高强度、高导电性的电触头材料。将氧化石墨烯(GO)和CeO_(2)纳米粒子优良的电学和力学性能引入到电接触性能稳定的铜基复合材料中,采用放电等离子烧结(SPS)的方法制备了Cu/30Cr、0.5GO/CeO_(2)-Cu/30Cr、1.0GO/CeO_(2)-Cu/30Cr三种电触头材料,研究氧化石墨烯负载氧化铈对铜基复合材料性能的影响。研究结果显示在烧结过程中,GO被还原为rGO,原位形成的Cr_(3)C_(2)和CeO_(2)纳米颗粒的位错钉扎效应对材料起到了强化作用,氧化石墨烯负载氧化铈的加入提高了复合材料的综合性能。

表面负载还原氧化石墨烯对泡沫铜热扩散系数的影响

为研究及提升泡沫铜的热扩散性能,利用不同溶剂制备氧化石墨烯混合溶液,通过机械沉积(GO-无水乙醇-丙酮混合溶液沉积)、电沉积(GO-CuS4O混合溶液电沉积、KH550改性GO电沉积)两种不同的沉积方法将氧化石墨烯(GO)附着到经过预处理的泡沫铜表面,后通过高温还原法去除氧化石墨烯表面多余的含氧基团,将其还原为还原氧化石墨烯(rGO),研究材料热扩散性能及泡沫铜表面rGO的存在状态。研究结果表明,通过GO-无水乙醇-丙酮混合溶液沉积的泡沫铜表面沉积层最为均匀完整,经高温还原后性能提升也最为明显,其低温热扩散系数由纯泡沫铜的29.06 mm^(2)/s提高为56.81 mm^(2)/s,提升了95.5%。与热扩散系数为50.26 mm^(2)/s的T2铜片相比,其热扩散系数亦提高13.09%。GO在泡沫铜表面的沉积方式对沉积效果影响显著,GO经过高温还原为rGO后均可以有效提升泡沫铜的热扩散性能。

Anomalous moire pattern of graphene investigated by scanning tunneling microscopy： Evidence of graphene growth on oxidized Cu（111）

The growth of graphene on oriented （111） copper films has been achieved by atmospheric pressure chemical vapor deposition. The structural properties of as-produced graphene have been investigated by scanning tunneling microscopy. Anomalous moir6 superstructures composed of well-defined linear periodic modulations have been observed. We report here on comprehensive and detailed studies of these particular moir6 patterns present in the graphene topography revealing that, in certain conditions, the growth can occur on the oxygen-induced reconstructed copper surface and not directly on the oriented （111） copper film as expected.

腔体材料对氧化铜箔衬底上制备石墨烯的影响

传统的化学气相沉积法制备的石墨烯普遍存在晶畴面积小、晶界缺陷多的问题,严重制约了大面积石墨烯的性能及应用。本文采用低压化学气相沉积技术在受限生长腔中的氧化铜箔衬底上制备石墨烯,对比研究了石英和刚玉两种材质的受限生长腔中,不同甲烷流量和生长时间条件下氧化铜箔衬底上石墨烯的形核生长状况。结果表明,相同生长条件下,相较于石英受限生长腔,虽然刚玉受限生长腔中石墨烯的晶畴尺寸较小,但是氧化铜箔衬底表面沉积的杂质颗粒较少,因而石墨烯的形核密度较低,晶体质量较高,更有利于大尺寸、高质量石墨烯的制备。

硫化铜/氧化石墨烯/壳聚糖/纳米羟基磷灰石复合材料的抗菌及促成骨作用

目的探讨硫化铜(CuS)/氧化石墨烯(GO)/壳聚糖(CS)/纳米羟基磷灰石(nHA)复合材料(CGCHs)的抗菌和促成骨作用及其作用机制。方法采用水热法合成CuS/GO纳米颗粒,通过原位沉淀法合成CS/nHA支架和CGCHs支架,检测材料表征、光热转换性能和生物安全性,评估CGCHs组和近红外光(NIR)照射下CGCHs(CGCHs+NIR)组的细菌抑制效果及其对细菌生物膜相关基因表达的影响,观察CGCHs和CS/nHA不同材料组的促成骨分化和成骨、破骨相关基因表达。结果CGCHs是具有高度孔隙率的三维支架,在CuS/GO浓度为200μg/mL时CGCHs同时兼具良好的红外升温效果和生物安全性。琼脂糖平板涂菌和细菌死活染色结果均表明CGCHs+NIR组抗菌性能最佳,生物膜相关基因qPCR检测证实其具有抑制细菌生物膜相关基因表达的作用。茜素红染色结果表明CGCHs具有良好的体外促成骨性能,体外共培养3、7、14、21和28 d qPCR结果表明CGCHs对成骨早期和晚期相关基因表达均具有促进作用。与破骨细胞共培养结果可观察到CGCHs具有抑制破骨细胞形成的作用,细胞凋亡检测结果进一步验证这一结论,破骨分化相关基因qPCR检测结果表明,CGCHs主要通过抑制抗酒石酸酸性磷酸酶、组织蛋白酶K、CTR、P65和P38在共培养7、14 d的表达来抑制破骨细胞的分化。结论作为纳米复合材料,CGCHs生物安全性好,具有良好的红外光热协同抗菌作用,在促成骨分化的同时抑制破骨细胞分化,有望为感染性骨缺损治疗提供新的思路。