多孔纳米立方FeSe2/石墨烯复合材料的可控构建及在钠离子电池中的应用

设计具有较高比容量和循环稳定性的负极材料对于钠离子电池的发展至关重要。过渡金属硒化物因其具有较高的理论容量而成为潜在的负极材料。但是,硒化物电导率低下且在钠离子嵌入/脱出的过程中会发生较大程度的体积膨胀,导致比容量快速下降。因此,结构调控显得尤为重要。通过常规水热法在二维还原氧化石墨烯（rGO）上原位生长多孔纳米立方体FeSe₂,制备了具有更多活性位点和结构更加稳定的FeSe₂/rGO复合材料。当用作钠离子电池的负极时,复合材料FeSe₂/rGO在0.2 A/g时比容量为694.6 mA?h/g,在2.0 A/g电流密度下,循环300圈后比容量为300 mA?h/g。     

Fe2O3/rGO纳米复合物的制备及其储锂和储钠性能

金属氧化物可通过电化学转换反应与锂离子及钠离子发生多电子可逆结构转换,是一类极具应用前景的高容量锂离子和钠离子电池负极材料。实验以氧化石墨烯和铁盐为前驱体,采用简单的溶剂法,成功将Fe₂O₃纳米单晶粒子均匀负载于石墨烯的导电片层上,获得Fe₂O₃/rGO(还原氧化石墨烯)纳米复合材料。复合电极在锂离子和钠离子电池中都表现出优异的充放电性能和循环稳定性。实验结果表明石墨烯的包覆不仅能降低Fe₂O₃发生转换反应的电荷传递阻抗,而且能够稳定电极在循环过程中带来的结构转变,极大改善电极大电流充放能力和循环稳定性。本研究为发展高容量的锂离子和钠离子电池负极材料提供了可行的途径。     

Synthesis and Electrochemical Performance of Co3O4/Graphene

Co3O4/reduced graphene oxide composites were synthesized via a simple electrochemical method from graphene oxide and Co（NO3）2·6H2O as raw materials.Co3O4 nanoparticles with sizes of around 30-50 nm were distributed on the surface of graphene nanosheets confirmed by scanning electron microscopy and transmission electron microscopy.Electrochemical properties of Co3O4/graphene composite were tested by cyclic voltammetry,galvanostatic charge-discharge,and electrochemical impedance spectroscopy.The Co3O4/reduced graphene oxide composite was used as the pseudocapacitor electrode in the 2 mol/L NaOH aqueous electrolyte solution.The Co3O4/reduced graphene oxide composite electrode exhibited a specific capacitance of 357 F/g at a current density of 0.5 A/g in a three-electrode system.72％ of capacitance was retained when the current density increased to 3 A/g.The Co3O4/reduced graphene oxide composite prepared electrodes show a high rate capability and excellent long-term stability.After 1000 cycles of charge and discharge,the capacitance is still maintained 87％ at a current density of 1 A/g,indicating that the composite is a oromising alternative electrode material used for supercapacitors.     

水热法制备Fe3O4/rGO纳米复合物作为锂离子电池阳极材料

以氢氧化铁为四氧化三铁的前驱体,氧化石墨烯（GO）为还原石墨烯（rGO）的前驱体,以水合肼和二水合柠檬酸三钠为混合还原剂,采用水热法制备了还原石墨烯负载四氧化三铁纳米颗粒（Fe₃O₄/rGO）的复合材料。通过透射电子显微镜（TEM）、X-射线衍射（XRD）和热重分析（TGA）对产物的形貌、结构和组成进行了表征。以锂片为对电极进行了扣式电池的组装,通过恒电流充放电和循环伏安法对其电化学性能进行了测试。材料具有均一的形貌,rGO具有较高的还原程度且可以在充放电过程中缓冲Fe₃O₄纳米颗粒的体积变化,使得Fe₃O₄/rGO纳米复合物具有较好的电化学性能。     

Synthesis of iron oxide cubes/reduced graphene oxide composite and its enhanced lithium storage performance

Fe₃O₄ is considered as a promising electrode material for lithium-ion batteries(LIBs) due to its low cost and high theoretical capacity(928 mAh/g).Nevertheless,the huge volume expansion and poor conductivity seriously hamper its practical applications.In this study,we use a facile hydrothermal reaction together with a post heat treatment to construct the three-dimensional heterostructured composite(Fe₃O₄/rGO) inwhich reduced graphene oxide sheets wraped the Fe₃O₄ submicron cubes as the conductive network.The electric conduction and electrode kinetics of lithium ion insertion/extraction reaction of the composite is enhanced due to the assist of conductive rGO,and thus the Listorage performance is obviously improved.The composite exhibits a reversible charge capacity of772.1 mAh/g at the current density of 0.1 A/g,and the capacity retention reaches 70.3% after400 cycles at0.5 A/g,demonstrating obviously higher specific capacity and rate capability over the Fe₃O₄ submicron cubes without rGO,and much superior cycling stability to the parent Fe_2 O_3 submicron cubes without rGO.On the other hand,as a synergic conductive carbon support,the flexible rGO plays an important role in buffering the large volume change during the repeated discharge/charge cycling.     

二硫化钼量子点/还原氧化石墨烯复合材料的制备及其光催化降解有机染料、四环素和Cr（VI）

以钼酸钠、L-半胱氨酸和氧化石墨烯为原料,采用一锅溶剂热还原法制备了二硫化钼量子点/还原氧化石墨烯（MoS₂ QDs/rGO）复合材料,分别以罗丹明B、亚甲基蓝、四环素和Cr（VI）为目标污染物,研究了复合材料的可见光响应光催化降解性能。结果显示,MoS₂ QDs/rGO对两种染料和Cr（VI）的光催化降解率均可达97%以上,对四环素的光催化降解率为69%;循环使用10次,对目标染料的降解率均保持在90%以上。说明MoS₂ QDs/rGO具有良好的催化活性和稳定性。在降解体系中分别加入异丙醇、对苯醌和乙二胺四乙酸二钠捕获剂,结果显示,超氧自由基（?O₂^-）是MoS₂ QDs/rGO光催化反应的主要活性物种。     

Ni/Mn3O4/NiMn2O4@RGO空心微球负极的制备及其储钠性能

采用溶剂热法制备前驱体,后经350 °C热处理,首次合成了空心结构的NiMn₂O₄微球以及不同含量氧化石墨烯包覆的Ni/Mn₃O₄/NiMn₂O₄@RGO复合材料. 电化学性能测试表明,复合负极材料中,含25wt%还原氧化石墨烯的材料储钠性能最佳,其在50 mA·g^-1电流密度下,100次循环后放电比容量保持在187.8 mAh·g^-1,且800 mA·g^-1电流密度下的可逆容量高达149.9 mAh·g^-1,明显优于NiMn₂O₄及其他石墨烯基复合材料. 研究指出,复合材料性能的提升得益于空心微球和还原的氧化石墨烯构成的特殊结构,一方面缩短了电子/离子传输距离,缓解了体积效应,另一方面高导电网络有效增强了活性物质利用率.     

Co3(HCOO)6@rGO 作为锂离子电池负极材料的研究

MOFs材料作为一类新型的锂离子电池电极材料而受到广泛关注和研究. 作者通过溶液扩散法将Co₃(HCOO)₆原位负载在 rGO（还原氧化石墨烯）上制备出Co₃(HCOO)₆@rGO复合材料. 将Co₃(HCOO)₆@rGO作为锂离子电池负极材料,以500 mA·g^-1的电流密度恒电流充放电循环 100 周后,仍然保持有 926 mAh·g^-1 的比容量,亦表现出很好的倍率性能. 循环伏安和X-射线光电子能谱测试表明,Co₃(HCOO)₆@rGO材料上的Co²⁺和甲酸根在充放电过程中均发生可逆的电化学反应. 对比同样采用溶液扩散法合成的 Co₃(HCOO)₆ 的测试结果发现,rGO起到活化甲酸根的电化学反应的作用,同时也改善了Co₃(HCOO)₆的倍率性能. 将MOFs材料与rGO复合为优化 MOFs 材料的电池性能提供了一个新思路.     

Thermal properties of alkaline sodium borohydride solutions

Alkaline sodium borohydride solutions are potential hydrogen sources for fuel cells. Thermal properties of the NaBH₄–NaOH–H₂O ternary system were measured by DSC and temperature-rise calorimetry. Liquidus temperatures showed that it is possible to store and use the solutions well below 0 °C if NaOH concentration is less than 20 wt%. The solubility of sodium borohydride was found to be large in these solutions, but decreased with increasing NaOH concentration. The optimum composition for alkaline borohydride solutions seems to be 15 wt% NaBH₄ in 10 wt% NaOH considering both the liquidus temperature and hydrogen storage density.     

Unraveling the stabilization mechanism of solid electrolyte interface on ZnSe by rGO in sodium ion battery

Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochemical performance of SIBs,remains at its infancy.Here in this paper,ZnSe@C nanoparticles were prepared from ZIF-8 and the SEI layers on these electrodes with and without reduced graphene oxide(rGO)layers were examined in details by X-ray photoelectron spectroscopies at varied charged/discharged states.It is observed that fast and complicated electrolyte decomposition reactions on ZnSe@C leads to quite thick SEI film and intercalation of solvated sodium ions through such thick SEI film results in slow ion diffusion kinetics and unstable electrode structure.However,the presence of rGO could efficiently suppress the decomposition of electrolyte,thus thin and stable SEI film was formed.ZnSe@C electrodes wrapped by rGO demonstrates enhanced interfacial charge transfer kinetics and high electrochemical performance,a capacity retention of 96.4%,after 1000 cycles at 5 A/g.This study might offer a simple avenue for the designing high performance anode materials through manipulation of SEI film.     

磷酸钒锂/石墨烯复合正极材料的制备及表征

通过三聚氰胺甲醛树脂(MR)中的羟基与石墨烯氧化物(GO)中的羧基发生的沉淀反应来制备功能化的氧化石墨烯前驱体,然后利用溶胶-凝胶及高温热处理方法制备磷酸钒锂/石墨烯复合材料,利用此材料制备了电池电极,并对电极材料进行了结构和电化学表征。结果表明,所得磷酸钒锂为单斜晶系结构,石墨烯堆叠程度显著降低,也有效避免了磷酸钒锂颗粒的团聚,提高了材料的电化学性能。电池的充放电曲线极化较小,在3.0~4.3 V的区间内20 C倍率仍有86 mA·h/g的可逆容量。0.1 C循环100次后容量为119.7 mA·h/g,容量保持率94%。在3.0~4.8 V的高电压区间,10 C倍率下可逆容量80 mA·h/g,0.1 C循环100次后仍有145.6 mA·h/g的可逆容量。优异的循环和倍率性能以及较低的碳含量符合锂离子正极材料实用的要求。     

Bi4V2O11/石墨烯异质结光催化剂的制备及其在降解抗体污染物中应用

发展和设计高效、廉价和稳定的光催化剂用于抗生素污染物降解仍然存在巨大的挑战。 本文通过一种便捷的水热方法制备了Bi₄V₂O₁₁/石墨烯复合材料并用于可见光下抗生素污染物光催化降解。 通过自由基追踪实验,确认了光催化降解过程中活性物质为h⁺和·OH基团。 根据实验结果,提出了相应的反应机理。 石墨烯的引入可以有效地促进光生电子-空穴对的分离,从而增强光催化活性。 该复合催化剂展现出良好的活性和稳定性。 该方法以石墨烯为载体制备了光催化降解材料,为高性能光催化剂的制备提供了参考。     

纳米银/二维石墨相氮化碳/还原氧化石墨烯复合材料的制备及其光催化降解抗生素

为优化石墨相氮化碳(g-C₃N₄)光催化剂的结构,改善其对污染物的降解性能,本文以三聚氰胺为前驱体,通过高温煅烧和热氧化剥离制备了二维石墨相氮化碳(2D-C₃N₄),并用光还原法一步合成纳米银/二维石墨相氮化碳/还原氧化石墨烯(Ag/2D-C₃N₄/rGO)复合光催化剂。通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、光致发光光谱(PL)、X射线光电子能谱(XPS)、氮气吸附脱附等温曲线(BET)等对材料进行表征。 以头孢曲松钠为目标污染物,探究pH值、催化剂用量、头孢曲松钠初始浓度等因素对催化剂的吸附、降解性能的影响,并探究降解反应机理。 当pH=6.0,催化剂用量为0.3 g/L,头孢曲松钠初始浓度为10.0 mg/L时,复合材料对头孢曲松钠的降解率可达到89.1%。 催化剂的稳定性较强,具有实际应用价值,可用于处理含头孢类抗生素的废水。     

铂/{还原氧化石墨烯/硅钨酸盐}_n复合物的制备及其电催化性能

利用层层自组装(LBL)结合原位光照还原法,制备了一系列{还原氧化石墨烯/多金属氧酸盐}n多层复合膜({rGO/POMs}_n),并以此作为载体,再通过恒电势法将Pt纳米粒子电沉积到复合膜载体上,得到一种P t/{rGO/SiW_(12)}_n燃料电池阳极纳米复合膜催化剂。用紫外可见分光光度计(UV-Vis)、原子力显微镜(AFM)以及扫描电子显微镜(SEM)等技术手段对载体复合多层膜的生长情况以及负载Pt纳米簇的表面形貌进行表征。结果表明,载体多层膜{rGO/SiW_(12)}_6被连续均匀地组装到了不同基底(氧化铟锡,ITO或玻碳,GC)表面且多层膜表面平整,在选定恒电势下,沉积于其表面的Pt纳米粒子具有花簇状形貌且分布均匀。比较研究了分别引入3种不同的多金属氧酸盐(硅钨酸盐SiW_(12),磷钼酸盐PMo_(12),磷钨酸盐PW_(12))制得的多层复合膜催化剂,即Pt/{rGO/SiW_(12)}_6、Pt/{rGO/PMo_(12)}_6和Pt/{rGO/PW_(12)}_6。电化学实验研究表明,在甲醇酸性溶液中,Pt/{rGO/SiW_(12)}_6复合膜相较于Pt/{rGO/PMo_(12)}_6、Pt/{rGO/PW_(12)}_6和Pt作为催化剂对甲醇氧化具有更好的电催化活性、电化学稳定性以及更优异的抗CO毒化性能,是一种颇有应用前景的燃料电池阳极催化剂。     

Enhanced Efficiency of Dye-sensitized Solar Cells Using rGO@TiO2 Nanotube Hybrids

We established a novel strategy for the synthesis of reduced graphene oxide(rGO)@TiO₂ nanotube hybrids using an 18 W UV-assisted photo-catalytic reduction method for utilization as photo-anode of dye-sensitized solar cells(DSSCs). The photo-conversion efficiency of DSSCs was significantly enhanced after the addition of rGO, and in addition, the photo-anode showed decreased internal resistance. Analysis of rGO@TiO₂ hybrids by transmissions scanning electron microscopy(TEM), X-ray diffraction(XRD), Raman spectra, N₂ adsorption and desorption, atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS) demonstrates that the rGO modified TiO₂ nanotubes can increase the short-circuit current and the conversion efficiency of dye-sensitized solar cells. The efficiency is improved by almost two folds as much compared to those of the bare TiO₂ nanotubes.     

A novel synthesis of Nb_2O_5@rGO nanocomposite as anode material for superior sodium storage

The development of novel anode materials,with superior rate capability,is of utmost significance for the successful realization of sodium-ion batteries(SIBs).Herein,we present a nanocomposite of Nb_2 O_5 and reduced graphene oxide(rGO) by using hydrothermal-assisted microemulsion route.The water-in-oil microemulsion formed nanoreactors,which restrained the particle size of Nb_2 O_5 and shortened the diffusion length of ions.Moreover,the rGO network prevented agglomeration of Nb_2 O_5 nanoparticles and improved electronic conductivity.Consequently,Nb_2 O_5@rGO nanocomposite is employed as anode material in SIBs,delivering a capacity of 195 mAh/g after 200 charge/discharge cycles at 0.2 A/g.Moreover,owing to conductive rGO network,the Nb_2 O_5@rGO electrode rende red a specific capacity of 76 mAh/g at high current density of 10 A/g and maintained 98 mAh/g after 1000 charge/discharge cycles at 2 A/g.The Nb_2 O_5@rGO electrode material prepared by microemulsion method shows promising possibilities for application of SIBs.     

Photocatalytic Reduction Synthesis of Ternary Ag Nanoparticles/Polyoxometalate/Graphene Nanohybrids and Its Activity in the Electrocatalysis of Oxygen Reduction

Ternary Ag nanoparticles (NPs)@polyoxometalate (POM)/reduced graphene oxide (rGO) nanohybrids were prepared by a facile photoreduction method, using POM as the photocatalyst, reducing and bridging molecules. The structure of the nanohybrids was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, etc. Most importantly, both the rotating disk electrode and rotating ring-disk electrode tests indicated that the Ag NPs@POM/rGO nanohybrids exhibited excellent electrocatalytic activity towards oxygen reduction reaction via a direct four-electron transfer pathway due to the synergistic effect of Ag NPs and rGO.     

Fe_3O_4/RGO复合材料的制备及其电化学性能研究

以改进Hummers法合成的氧化石墨烯(GO)为前驱体,通过水热法结合烧结工艺制备了四氧化三铁/还原氧化石墨烯(Fe_3O_4/RGO)复合材料。利用X射线衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)等手段对复合材料的理化性能进行表征;通过充放电测试、循环伏安(CV)和电化学阻抗谱(EIS)等技术,综合考察了材料的储锂性能及电化学性能增强机制。结果表明,在200和600 m A/g电流密度下,Fe_3O_4/RGO复合负极循环60次后的放电比容量分别保持在709和479 mAh/g,表现出良好的倍率性能;相较于纯Fe_3O_4负极,复合负极呈现出更优异的锂电性能,其电化学性能的改善得益于RGO能增强材料的电导性和结构稳定性。     

石墨烯修饰玻碳电极对多巴胺的电催化氧化

通过3-巯丙基三乙氧基硅烷(METMS)将氧化石墨烯(GO)固载到玻碳电极(GCE)表面, 用电化学方法还原GO制备石墨烯修饰玻碳电极(rGO-METMS-GCE). 利用傅里叶变换红外光谱(FTIR)、 拉曼光谱(Raman)、 扫描电子显微镜(SEM)和原子力显微镜(AFM)等技术对GO和rGO-METMS-GCE的结构和表面形貌进行表征. 采用循环伏安(CV)和差分脉冲溶出伏安(DPV)法研究了rGO-METMS-GCE对多巴胺(DA)的电催化氧化性能及反应机理. 结果表明, 与裸GCE相比, DA在rGO-METMS-GCE电极上的氧化还原峰电流(i_pa和i_pc) 增大4倍, 氧化峰电位负移106 mV, 氧化峰与还原峰电位差(ΔE_p)从202 mV降低至66 mV, DA电化学氧化可逆性明显改善, 表明rGO-METMS-GCE对DA电化学氧化具有显著电催化作用. DA在rGO-METMS-GCE上的反应机理为单电子转移过程.     

NiCo_2S_4六角片作为钠离子电池负极材料的电化学性能及储钠动力学

通过共沉淀以及后续的气相硫化成功制备了横向边长约为2μm,纵向厚度约为30 nm的NiCo_2S_4六角片,并研究了其作为钠离子电池负极材料的电化学性能。电化学性能测试结果显示在1000 mA·g~(-1)的电流密度下,NiCo_2S_4电极循环60次后仍然可保持约387mAh·g~(-1)的可逆比容量。此外,NiCo_2S_4电极还具有良好的倍率性能,在200、400、800、1000和2000mA·g~(-1)的电流密度下,容量分别为542、398、347、300和217mAh·g~(-1)。通过进一步动力学机制分析发现,NiCo_2S_4电极的良好的倍率性能得益于其二维片层状结构诱导产生的赝电容。上述结果表明,NiCo_2S_4纳米六角片是一种极具潜力的钠离子电池负极材料。