一步法制备三维还原氧化石墨烯/NiO超级电容器电极材料及其性能研究

本研究以氧化石墨烯分散液(GO)和硝酸镍(Ni(NO₃)₂·6H₂O)为前驱体, 通过一步水热法制备自支撑三维还原氧化石墨烯/NiO复合电极材料(3D rGO/NiO)。用XRD和SEM等分析结果表明, 纳米NiO颗粒均匀分散在三维多孔石墨烯表面。当GO与Ni(NO₃)₂·6H₂O质量比为1 : 4时, 3D rGO/NiO在电流密度为1 A·g^-1 下比电容可达1208.8 F·g^-1; 当电流密度从0.2 A·g^-1增加到10 A·g^-1时, 复合电极材料电容保持率高于72.6%; 在电流密度为10 A·g^-1下进行恒流充放电循环测试10000次后, 其比电容仍然保持为初始比电容的93%, 表明该复合电极材料具有良好的倍率性能和循环稳定性能。3D rGO/NiO复合电极材料具有比纯NiO或rGO更优异的电化学性能。     

超级电容器用CeO_2-MnO/3D石墨烯复合材料的制备

以西瓜瓜瓤为碳源,采用两步碳化法制备三维石墨烯(3D-Fiberbased Graphene,3D G)材料,并使用水热法制备了CeO_2-MnO/3DG复合材料,以期获得比电容高,循环寿命好的石墨烯超级电容器电极材料。结果表明:3DG材料具有较高比表面积,最高可达到332m~2·g~(-1)。CeO_2-MnO/3DG复合材料具有三维导电网络结构,金属氧化物颗粒在石墨烯片层间生长均匀,粒径在10nm左右。电化学测试结果显示:在0.5 mol·L~(-1)的Na_2SO_4溶液中,电流密度1A·g~(-1),当摩尔比MnO∶CeO_2=4∶1,复合负载量在80%时得到的CeO_2-MnO/3D G复合材料拥有最高比电容,达308.5F·g~(-1),经过1 000次循环充放电测试比电容保持率为95.5%。CeO_2-MnO/3DG复合材料电化学性能的提高主要是因为两种金属氧化物复合负载与石墨烯的协同作用。     

疏松多孔CoFe2O4-还原石墨烯电极复合材料的制备与性能

采用原位溶剂热法,以氧化石墨烯（GO）与Co2+、Fe3+为原料制备疏松多孔的纳米CoFe₂O₄-还原氧化石墨烯（CoFe₂O₄-rGO）复合材料。采用XRD、Raman、SEM和HRTEM测试表征了纳米CoFe₂O₄-rGO复合材料的结构与形貌。测试结果表明,纳米CoFe₂O₄-rGO复合材料具有三维结构。自组装的多孔CoFe₂O₄纳米球粒径约为200 nm,在rGO上均匀分散,解决了CoFe₂O₄易团聚的问题。电化学测试结果表明,纳米CoFe₂O₄-rGO复合材料具有较高的比容量及优异的循环和倍率性能,在100 mA·g-1的电流密度下其比容量为1 262 mAh·g-1,50次循环后比容量仍能保持在642 mAh·g-1;并在2 000 mA·g-1的大电流密度下仍具有221 mAh·g-1的比容量。纳米CoFe₂O₄-rGO复合材料拥有更优异的电化学性能的原因在于CoFe₂O₄纳米球在rGO上均匀分布。三维结构增加了Li+储存的活性位点,有效缓解了电极的体积收缩/膨胀效应,提高了纳米CoFe₂O₄-rGO复合材料的导电性。      

还原氧化石墨烯/氢氧化钴复合材料的制备与电化学性能研究

采用溶剂热法制备了还原氧化石墨烯/氢氧化钴[rGO/Co(OH)_2]复合材料,通过X射线衍射、扫描电镜、拉曼光谱、热失重分析和氮气吸脱附表征了材料的形貌、结构和组成,并采用循环伏安法和恒电流充放电测试了复合材料的电化学性能。结果表明:球状的Co(OH)_2颗粒均匀分散在rGO表面形成了介孔占优的复合材料rGO/Co(OH)_2;由于Co(OH)_2和rGO的协同作用,复合材料表现出良好的电化学性能,在电流密度为1A/g时,比电容为631F/g,循环1000次后电容的保持率仍为83%。     

三维多级孔石墨烯/聚苯胺复合材料的制备及电化学性能

采用水热法合成聚糠醇（PFA）,探究了表面活性剂聚乙烯吡咯烷酮（PVP）添加量和反应时间对PFA微观形貌的影响。将改进Hummers法制备的氧化石墨烯（GO）对PFA、泡沫Ni进行包覆,探讨了PFA模板与GO不同质量比的包覆效果。去模板后成功构筑三维大孔石墨烯（3D rGO）,3D rGO再经KOH活化获得三维多级孔石墨烯（3D PrGO）,3D PrGO经与聚苯胺（PANI）原位复合获得3D PrGO/PANI复合材料。采用XRD、SEM、TEM、FTIR、XPS和比表面（BET）分析法对材料的物相组成、微观结构、形貌、比表面和孔径进行表征,采用循环伏安、恒流充放电、电化学阻抗谱分析了3D PrGO/PANI复合材料的电化学性能。结果表明:通过控制糠醇、PVP及水的比例,在180℃水热反应24 h成功制备了球径在500 nm左右的PFA微球。在PFA与GO质量比为1∶1时包覆效果最佳。450℃热处理6 h成功去除PFA模板并形成400~600 nm左右的大孔,经KOH活化后,在3D PrGO上形成介孔结构。3D PrGO/PANI复合材料在0.5 A/g电流密度下比电容为433 F/g,在1 A/g下1 000次循环充放电之后,3D PrGO/PANI复合材料的比电容保留率为75%,高于纯PANI的69%。      

还原氧化石墨烯/Mn_3O_4纳米复合材料的合成及其在超级电容器中的应用

以改进的Hummers法所制氧化石墨烯/硫酸锰(GO/MnSO4)悬浊液为原料,原位合成GO/MnO2复合物,再经低温热处理制备还原氧化石墨烯/Mn3O4(rGO/Mn3O4)纳米复合材料。通过改变GO/MnSO4悬浊液中MnSO4的质量含量实现rGO/Mn3O4复合物中Mn3O4质量分数的可控调变。该法充分利用氧化石墨烯原液中的锰离子,可节省原料,同时可避免氧化石墨烯繁琐的分离过程并简化实验步骤。所得复合材料作为超级电容器电极材料展现良好的电化学电容性能,在饱和K2SO4电解质溶液和50 mA·g-1的电流密度下,Mn3O4质量含量为88%时其比电容达284 F·g-1。     

3D多级孔rGO/TiO2复合材料的构筑及其光催化性能研究

研究以聚苯乙烯(PS)微球为模板、氧化石墨烯(GO)和钛酸四丁酯(TBT)为原料, 采用溶胶-凝胶法, 利用GO与PS上的官能团和TiO₂前驱体的多重配位反应, 制备了3D多级孔rGO/TiO₂(PS)复合材料。通过不同手段对样品的结构和形貌进行表征, 研究了PS添加量对rGO/TiO₂复合材料晶体结构、微观形貌及光催化性能的影响。分别在模拟紫外光和可见光下, 以盐酸四环素(TTCH)为目标污染物对不同PS加入量制备的3D多级孔rGO/TiO₂(PS)复合材料的光催化性能进行评价, 并在模拟可见光下, 对3D多级孔rGO/TiO₂(5wt%PS)复合材料进行了多次循环回收测试。结果表明: rGO/TiO₂(PS)复合材料具有3D多级孔块体结构, GO作为基体的增强相通过Ti-O-C键保持多级孔刚性骨架结构的稳定。引入PS增大了rGO/TiO₂(PS)复合材料的比表面积, 3D多级孔rGO/TiO₂(7wt% PS)复合材料对TTCH吸附效率最高, 而3D多级孔rGO/TiO₂(5wt%PS)复合材料光催化活性和稳定性最高, 且经过4次循环回收测试, 其光催化效率仍达81.02%; 模板剂PS的最佳引入量为5wt%。     

近球状钼酸镍/多壁碳纳米管复合材料的制备及其赝电容性能

以硝酸镍、钼酸钠和多壁碳纳米管为原料, 通过水热反应法制备了钼酸镍/多壁碳纳米管(NiMoO₄/MWCNTs)复合材料。采用扫描电子显微镜、X射线能谱和X射线衍射对材料组成和形貌进行表征。结果表明: MWCNTs 很好地包覆在球状NiMoO₄外表面, 且各元素均匀地分布在材料中。循环伏安和电化学阻抗实验证实MWCNTs显著增强了NiMoO₄的氧化还原信号和电荷转移动力学特性。电容测试实验进一步表明, 复合材料较NiMoO₄单一材料具有更高的比电容、倍率特性及循环稳定性, 且当MWCNT含量为40 mg时, 所得产物(NiMoO₄/MWCNTs-40)具有最佳的电化学性能。电流密度为2 A/g时, NiMoO₄/MWCNTs-40复合材料的比电容高达1071 F/g; 当电流密度增大到10 A/g时, 比电容仍能保持原来的66.10%。在10 A/g的电流密度下, 经过2500次循环充放电后, NiMoO₄/ MWCNTs-40复合材料的比电容保持率高达95.85%, 表明该材料具有出色的循环稳定性。     

rGO/PANI/MnO2三元复合材料的制备和电化学性能

用水热合成法和冻干操作制备石墨烯/聚苯胺/二氧化锰三元复合材料(rGO/PANI/MnO₂),使用X射线衍射(XRD)、X射线光电子能谱(XPS)和扫描电子显微镜(SEM)对其进行了表征。结果表明,用这种简单高效的方法制备的复合材料,具有相互交联的网络状结构和自支撑特性。在反应过程中MnO₂与聚苯胺形成不规则的块状结构,共沉积在石墨烯自组装形成的网络片层上。这种复合材料具有良好的电容性能,比电容为388 F·g-1(0.5 A·g^-1),优于单纯的石墨烯(rGO,234 F·g-1)和聚苯胺电极(PANI,176 F·g-1)。使用这种复合材料作为正极、rGO作为负极组装的一种不对称超级电容器,能在0～1.6 V范围内可逆循环,功率密度为17.48 W·kg^-1时最大能量密度为13.5 Wh·kg^-1。     

纤维素纳米纤丝-还原氧化石墨烯/聚苯胺气凝胶柔性电极复合材料的制备与性能

利用高长径比的纤维素纳米纤丝（CNF）与片层结构的氧化石墨烯（GO）形成的CNF-GO复合水凝胶经抗坏血酸还原制备出CNF-还原氧化石墨烯（rGO）复合水凝胶材料。通过冷冻干燥法得到CNF-rGO复合气凝胶,并进一步通过苯胺单体在CNF-rGO复合气凝胶的孔道内原位聚合制备出CNF-rGO/聚苯胺（PANI）气凝胶柔性电极复合材料。研究了不同苯胺、CNF和GO的质量比对CNF-rGO/PANI气凝胶柔性电极复合材料的结构形貌和电化学性能的影响。结果表明,苯胺原位聚合后所得CNF-rGO/PANI复合气凝胶仍具有紧密的三维多孔网络结构。与rGO/PANI气凝胶电极复合材料相比,CNF-rGO/PANI气凝胶电极复合材料具有更理想的电容行为。当CNF与GO质量比为60∶40,PANI添加量为0.1 mol时,CNF-rGO/PANI气凝胶电极复合材料比电容可达85.9 Fg-1,且其电化学性能几乎不受弯曲程度的影响,展现出了良好的柔韧性和电化学性能。      

Reduced graphene oxide supersonically sprayed on wearable fabric and decorated with iron oxide for supercapacitor applications

We demonstrate the fabrication of wearable supercapacitor electrodes.The electrodes were applied to wearable fabric by supersonically spraying the fabric with reduced graphene oxide(rGO)followed by decoration with iron oxide(Fe2O3)nanoparticles via a hydrothermal process.The integration of iron oxide with rGO flakes on wearable fabric demonstrates immense potential for applications in high-energy-storage devices.The synergetic impact of the intermingled rGO flakes and Fe2O3 nanoparticles enhances the charge transport within the composite electrode,ultimately improving the overall electrochemical performance.Taking advantage of the porous nature of the fabric,electrolyte diffusion into the active rGO and Fe2O3 materials was significantly enhanced and subsequently increased the electrochemical interfacial activities.The effect of the Fe2O3 concentration on the overall electrochemical performance was investigated.The optimal composition yields a specific capacitance of 360 F g-1 at a current density of 1A g-1 with a capacitance retention rate of 89％after 8500 galvanostatic cycles,confirming the long-term stability of the Fe2O3/rGO fabric electrode.     

K2Ti6O13 Nanoparticle-Loaded Porous rGO Crumples for Supercapacitors

One-dimensional alkali metal titanates containing potassium,sodium,and lithium are of great concern owing to their high ion mobility and high specific surface area.When those titanates are combined with conductive materials such as graphene,carbon nanotube,and carbon nanofiber,they are able to be employed as efficient electrode materials for supercapacitors.Potassium hexa-titanate(K2Ti6O13,KTO),in particular,has shown superior electrochemical properties compared to other alkali metal titanates because of their large lattice parameters induced by the large radius of potassium ions.Here,we present porous rGO crumples(PGC)decorated with KTO nanoparticles(NPs)for application to supercapacitors.The KTO NP/PGC composites were synthesized by aerosol spray pyrolysis and post-heat treatment.KTO NPs less than 10 nm in diameter were loaded onto PGCs ranging from 3 to 5μm.Enhanced porous structure of the composites was obtained by the activation of rGO by adding an excessive amount of KOH to the composites.The KTO NP/PGC composite electrodes fabricated at the GO/KOH/TiO2 ratio of 1:3:0.25 showed the highest performance(275 F g−1)in capacitance with different KOH concentrations and cycling stability(83%)after 2000 cycles at a current density of 1 A g−1.     

Construction of hierarchical three-dimensional interspersed flower-like nickel hydroxide for asymmetric supercapacitors

Low-cost and easily obtainable electrode materials are crucial for the application of supercapacitors.Nickel hydroxides have recently attracted intensive attention owning to their high theoretical specific capacitance,high redox activity,low cost,and eco-friendliness.In this study,novel three-dimensional (3D) interspersed flower-like nickel hydroxide was assembled under mild conditions.When ammonia was used as the precipitant and inhibitor and CTAB was used as an exfoliation agent,the obtained exfoliated ultrathin Ni(OH)2 nanosheets were assembled into 3D interspersed flower-like nickel hydroxide.In this novel 3D structure,the ultrathin Ni(OH)2 nanosheets not only provided a large contact area with the electrolyte,reducing the polarization of the electrochemical reaction and providing more active sites,but also reduced the concentration polarization in the electrode solution interface.Consequently,the utilization efficiency of the active material was improved,yielding a high capacitance.The electrochemical performance was improved via promoting the electrical conductivity by mixing the as-synthesized Ni(OH)2 with carbon tubes (N-4-CNT electrode),yielding excellent specific capacitances of 2,225.1 F·g-1 at 0.5 A·g-1 in a three-electrode system and 722.0 F·g-1 at 0.2 A·g-1 in a two-electrode system.The N-4-CNT//active carbon (AC) device exhibited long-term cycling performance (capacitance-retention ratio of 111.4％ after 10,000 cycles at 5 A·g-1) and a high specific capacitance of 180.5 F·g-1 with a high energy density of 33.5 W·h·kg-1 and a power density of 2,251.6 W·kg-1.     

Size-controlled MoS<Subscript>2</Subscript> nanodots supported on reduced graphene oxide for hydrogen evolution reaction and sodium-ion batteries

Transition metal dichalcogenide nanodots (NDs) have received considerable interest.We report a facile bottom-up synthetic route for MoS2 NDs by using molybdenum pentachloride and L-cysteine as precursors in oleylamine.The synthesis of NDs with a narrow size distribution ranging from 2.2 to 5.3 nm,was tailored by controlling the reaction time.Because of its coating characteristics,oleyalmine leads to uniformity and monodispersity of the NDs.Moreover,the NDs synthesized have large specific surface areas providing active sites.Graphene possesses outstanding conductivity.Combining the advantages of the two materials,the 0D/2D material exhibits superior electrochemical performance because of the 2D permeable channels for ion adsorption,energy storage,and conversion.The as-prepared MoS2/rGO (～2.2 nm) showed a stable capacity of 220 mAh·g-1 after 10,000 cycles at the current density of 20 A·g-1.Furthermore,a reversible capacity ～140 mAh·g-1 was obtained at a much higher current density of 40 A·g-1.Additionally,this composite exhibited superior catalytic performance evidenced by a small overpotential (222 mV) to afford 10 mA·cm-2,and a small Tafel slope (59.8 mV·decade-1) with good acid-stability.The facile approach may pave the way for the preparation of NDs with these nanostructures for numerous applications.     

石墨烯包覆分子筛复合电极材料的制备及其性能研究

以4A分子筛(4A)和改进Hummers法制备的氧化石墨烯凝胶(GO)为原料, 按一定质量比进行混合超声分散, 以混合分散液为前驱体煅烧制备了氧化还原石墨烯(RGO)包覆的三维复合4A/RGO电极材料。采用X射线衍射(XRD)、拉曼光谱(Raman)、孔径分析、扫描电子显微镜(SEM)和电化学测试等方法研究了复合材料的结构、形貌及超级电容性能。测试结果表明, 4A均匀地穿插在RGO片层中, 阻止了RGO片层之间相互堆积, 而RGO片层之间相互链接, 形成三维空间导电网络, 提高了复合电极材料的导电性。当GO与4A质量比为1:6时, 复合材料在4 A/g电流密度下比电容可达450 F/g, 在此电流密度下循环800次后, 其比容量保持率为85.7%, 表现出良好的倍率性能和循环稳定性。该4A/RGO复合电极材料超级电容性能优于纯4A或RGO, 可归因于4A和RGO之间的协同效应。     

ZnCo2O4及ZnCo2O4/rGO复合材料的制备与电化学性能

采用一步水热法制备尖晶石型钴酸锌(ZnCo_2O_4)及钴酸锌/石墨烯(ZnCo_2O_4/rGO)复合材料,通过XRD,SEM和RST5000电化学工作站对材料的组分、表面形貌及电化学性能进行表征。通过改变水热温度,制备出具有辐射状花簇团结构、褶皱片层结构和表面光滑的球体结构的ZnCo_2O_4电极材料。结果表明:加入石墨烯后,ZnCo_2O_4呈规则的多边形结构,附着在石墨烯片上,两者的协同作用可有效改善电极材料的电化学性能;钴酸锌与氧化石墨烯的质量比为6∶1时得到的ZnCo_2O_4/rGO复合材料的比电容为205F/g,比纯ZnCo_2O_4的比电容提升了约114%。     

石墨烯负载花球状二氧化锰复合材料制备及其电容性能研究

利用高锰酸钾与乙醇之间的氧化还原反应,在多孔石墨烯表面沉积纳米二氧化锰花球,获得了一种新型的复合电极材料。通过XRD,TG,SEM,TEM等分析手段确定了材料的晶体结构、化学成分、微观形貌特征。电化学性能测试表明:纳米二氧化锰花球具有优异的比电容,但是倍率性能和循环性能不足。通过在石墨烯表面负载纳米二氧化锰花球,能够显著增加石墨烯的比电容,同时改善纳米二氧化锰花球的倍率性能和循环性能。采用0.5mol/L K_2SO_4电解液,进行三电极循环伏安测试,复合电极材料在2mV·s^-1扫速下的比电容高达295F·g^-1,在1000mV·s^-1扫速下,比电容仍然可达102F·g^-1,同时100mV·s^-1,1000次循环后,电容循环保持率可达96.3%。这表明石墨烯负载花球状二氧化锰材料是一种极具潜力的超级电容器电极材料。     

聚苯胺-石墨烯/聚酰亚胺复合导电纱的制备及其超电容特性

为了提高石墨烯/聚酰亚胺(rGO/PI)复合纱线电极的电化学性能,采用电化学聚合法在rGO/PI复合纱线表面沉积聚苯胺(PANI)颗粒,研究了沉积时间对PANI-rGO/PI复合导电纱的形貌及增重的影响。结果表明, PANI在rGO/PI复合纱线表面均匀沉积,且沉积量随着沉积时间的增加而增大。采用循环伏安法(CV)、恒流充放电法(GCD)研究了PANI-rGO/PI复合导电纱线的电化学行为。结果表明, PANI沉积时间对纱线电极的循环伏安特性、恒流充放电曲线等有很大的影响,当PANI沉积时间为900 s时,所得PANI-rGO/PI复合纱线电极的循环伏安特性和恒流充放电性能表现均最优,比电容为81.22 F·cm^-3,而rGO/PI纱线电极仅为16.4 F·cm^-3。以最优工艺制得的PANI-rGO/PI复合导电纱作为电极组装了纤维状超级电容器,采用交流阻抗谱法(EIS)、 CV及GCD对器件进行电化学性能表征。结果表明,该器件体积比电容可达41.73 F·cm^-3,在充放电3 000次后比电容依然能够维持在85%左右,所得纤维状超级电容器经过串联可成功驱动LED灯。