石墨烯量子点/介孔SiO2复合材料的研究进展

石墨烯量子点/介孔SiO2复合材料的发光效率是影响其应用的重要指标,文章从实验和理论两个方面总结了量子点/介孔复合材料发光效率的研究现状,分析了其发光效率的影响因素和理论预测方法,提出了建立石墨烯量子点/介孔SiO2复合材料发光效率模型的方法和亟待解决的关键问题。     

荷叶茎衍生多孔碳的制备及其在锂硫电池中的应用

以荷叶茎为原料,通过高温退火处理和KOH活化得到多孔碳,并将其作为硫的载体材料,最终得到C/S正极材料.通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、热重法(TG)、BET分析和喇曼光谱对目标产物进行了表征,研究了C/S正极材料的结构和形貌.将C/S作为锂硫电池正极材料进行电化学测试,其...     

二氧化锰/二氧化钛/介孔碳复合材料制备及其电化学性能

采用水热合成法制备了二氧化锰/二氧化钛/介孔碳复合材料,利用该复合材料制备了空气电极。通过X射线衍射仪(XRD)分析了复合材料的物相,用扫描电子显微镜(SEM)观察了复合材料的表面形貌,采用循环伏安法研究了空气电极的电化学性能。结果表明:在160℃条件下制备的复合材料结晶度更高,循环伏安测试表明空气电极可逆性较好。利用复合材料组装了锂空气电池,对其进行充放电测试,发现锂空气电池首次放电容量最高可达1 331 m Ah/g。     

纳米碳纤维作锂离子电池负极材料的嵌锂性能

用化学气相沉积法(CVD)制备了纳米碳纤维,并通过2800℃高温处理得到石墨化纳米碳纤维。采用XRD、SEM和TEM对所制的材料进行微结构分析,并考察其作为锂离子电池负极材料的嵌锂性能。结果表明:纳米碳纤维初次嵌锂容量可达到533mA·h/g,25次循环后可逆容量保持在274mA·h/g,循环效率超过99%;经过石墨化处理以后,材料初次可逆容量达到311mA·h/g,首次循环效率从55%提高到78%,25次循环后可逆容量的保持率为99%以上。     

碳纳米球薄膜的场发射特性

利用微波等离子体化学气相沉积法,在Si(100)衬底上制备了碳纳米球薄膜。利用拉曼光谱和场发射扫描电子显微镜研究了薄膜的结构以及表面形貌,表明碳纳米球薄膜是由约2～3μm长、100nm宽的无定形碳纳米片相互缠绕、交织成球状而构成的。在高真空系统中测量了碳纳米球薄膜的场发射特性,结果表明,碳纳米球薄膜具有良好的场发射特性,阈值电场为3.1V/μm,当电场增加到10V/μm时,薄膜的场发射电流密度可达到60.7mA/cm2。通过三区域电场模型合理地解释了碳纳米球薄膜在低电场、中间电场和高电场区域的场发射特性。     

碳包覆二硫化铼纳米球的制备及其储钠性能

二硫化铼(ReS₂)由于极弱的层间范德华力和独特的1T’相,使其非常适合作为钠离子电池(SIB)的负极材料,但是由于ReS₂具有电导率较低和充放电过程中体积膨胀的缺点,制约了其SIB性能的进一步提高。制备了一种碳包覆ReS₂(ReS₂/C)纳米球复合材料。通过水热反应制成自组装的ReS₂纳米球,ReS₂纳米球与葡萄糖混合后高温碳化得到ReS₂/C,碳在ReS₂纳米球间形成均匀的三维(3D)碳导电网络。对ReS₂/C负极进行了电化学性能测试。结果表明,3D碳导电网络能够提供电子快速传输的通道,并且3D碳导电网络包覆活性材料可以更好地承受结构应力。得益于均匀碳涂层形成的3D碳导电网络,ReS₂/C负极表现出优异的循环稳定性和倍率性能。研究结果表明,ReS₂/C负极在电流密度0.1、0.2、0.5、1、2和5 A·g^-1时,放电比容...     

碳修饰的HMCS@ReS2的合成及其储钠性能研究

二硫化铼(ReS₂)作为过渡金属二硫化物的一员,由于极弱的层间范德华相互作用、较弱的层间耦合能量和较大的层间距,在钠离子电池领域有着良好的应用前景。但是ReS₂自身较低的本征电导率和充放电过程中较大的体积膨胀严重限制了其电化学储钠能力。在空心介孔碳球(HMCS)上原位生长ReS₂纳米片(HMCS@ReS₂),将HMCS@ReS₂复合材料作为高性能钠离子电池负极。碳基材料的复合弥补了ReS₂电导率不足的缺陷,促进了电子的快速转移;空心介孔碳球为ReS₂的体积变化提供了足够的缓冲空间,维持了电极材料的结构稳定性。HMCS@ReS₂作为钠离子电池负极材料时有着优异的倍率性能和循环性能。结果表明,HMCS@ReS₂电极在0.2,0.5,1.0,2.0,5.0 A·g^-1的电流密度下分别表现出388.5,343.4,305.3,262.4,180.1 mAh·g^-1     

介孔ZnO微球的制备及其在染料敏化太阳能电池中的应用

制备了一种新型的染料敏化太阳电池的光阳极,该电极由溶剂合成的具有高比表面积和良好光散射特性的ZnO介孔微球组成。采用X射线衍射、扫描电子显微镜、能谱仪及N2吸附脱附等手段,分析了介孔ZnO微球的结构和形貌。所得介孔微球尺寸在亚微米范围,比表面积约为50m2.g-1。将ZnO介孔微球成功应用到染料敏化太阳电池中,当光阳极为3μm时,组成的原型器件的短路电流密度约为4.5mA.cm-2,开路电压约为602mV,转换效率可达1.28%。研究结果表明,ZnO介孔微球是一种优异的染料敏化太阳电池的光阳极材料。     

氮掺杂多孔碳纳米纤维的制备及其储钾性能

基于静电纺丝获得多孔碳纳米纤维,随后高温锻烧制备出氮掺杂多孔碳纳米纤维(N-CNF),并将其作为钾离子电池的负极材料.通过场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、X射线粉末衍射仪、Raman光谱仪和比表面积分析仪对目标产物进行了表征,研究了N-CNF负极材料的结构和形貌.N-CNF作为钾离子电池的...     

Au/SiO_2复合纳米颗粒膜的制备及退火行为研究

室温下用磁控溅射法在Si(111)衬底上生成Au/SiO2复合纳米颗粒膜。用扫描电子显微镜(SEM)和X射线衍射方法(XRD)对不同温度退火后的Au/SiO2复合薄膜的表面形貌、微观结构进行了表征。SEM结果表明,随着退火温度升高,Au纳米颗粒先形成大的聚集后出现分布均匀的超微颗粒。XRD结果显示700℃时Au的衍射峰最强,随后峰强有所减弱,这与SEM检测结果相吻合。另外实验结果证实在1000℃退火时自组装生成空间分布均匀(直径约为70nm)的Au纳米点,可以用来作为生长一维纳米材料的模板。     

Defect Strategy-Regulated MoSe2-Modified Self-Supporting Graphene Aerogels Serving as Both Cathode and Interlayer of Lithium-Sulfur Batteries

The severe shuttle effect and the sluggish redox reaction kinetics are the two most urgent issues with lithium-sulfur batteries (LSBs). In this work, Se vacancy-rich molybdenum selenide-modified graphene aerogels are designed to serve as both cathode host (MoSe_2-x@GA/S) and freestanding interlayers (MoSe_2-x@GA) for LSBs. The graphene network-supported binder-free sulfur host maximizes electron conductivity/Li⁺ migration rate and alleviates bulk expansion. The defect-rich MoSe_2-x with sulfiphilic-lithiophilic properties accelerates the nucleation and dissociation of Li₂S, while the insertion of a bifunctional interlayer not only facilitates the adsorption and conversion of polysulfides but also regulates the uniform lithium deposition and inhibit the growth of lithium dendrites. As a result, the assembled MoSe_2-x@GA/S+interlayer electrode obtains good feedback in terms of capacity enhancement and cycling stability, possessing a high initial discharge capacity of 1256.9 mA h g⁻¹ at 0.2 C and a slow decay ratio of 0.024% per cycle at a high current density of 1 C after 1000 long-term cycling, and achieve high specific capacity (720.6 mA h g⁻¹) at high sulfur loading (4.8 mg cm⁻²) and lean electrolyte (5.5 µL mg⁻¹) conditions. This insightful work contributes new ideas for the design of binder-free sulfur host and the application of defective electrocatalytic engineering.     

Zn2SiO4-Mg2SiO4复相陶瓷的合成与性能研究

利用醇盐溶胶-凝胶法合成（1-x）Zn2SiO4-xMg2SiO4陶瓷（x=0.1-0.9）。差热分析结合XRD分析表明（1-x）Zn2SiO4-xMg2SiO4的成相温度在800℃附近,1 150℃预烧粉体后,获得粒径为40-50 nm的Zn2SiO4-Mg2SiO4复相陶瓷粉末。复相陶瓷的最佳烧结温度在1 250℃-1 300℃,烧结过程中,部分组分产生了MgSiO3杂相。当x=0.6时,在1 250℃烧结后陶瓷的介电性能最优如下：εr=6.66,Q×f=174 800 GHz,τf=-38.7 ppm/℃,是一种有望应用于毫米波频段的新型介质陶瓷材料。     

Facile Spraying Synthesis and High‐Performance Sodium Storage of Mesoporous MoS2/C Microspheres

A facile one‐step spraying synthesis of MoS₂/C microspheres and their enhanced electrochemical performance as anode of sodium‐ion batteries is reported. An aerosol spraying pyrolysis without any template is employed to synthesize MoS₂/C microspheres, in which ultrathin MoS₂ nanosheets (≈2 nm) with enlarged interlayers (≈0.64 nm) are homogeneously embedded in mesoporous carbon microspheres. The as‐synthesized mesoporous MoS₂/C microspheres with 31 wt% carbon have been applied as an anode material for sodium ion batteries, demonstrating long cycling stability (390 mAh g^?1 after 2500 cycles at 1.0 A g^?1) and high rate capability (312 mAh g^?1 at 10.0 A g^?1 and 244 mAh g^?1 at 20.0 A g^?1). The superior electrochemical performance is due to the uniform distribution of ultrathin MoS₂ nanosheets in mesoporous carbon frameworks. This kind of structure not only effectively improves the electronic and ionic transport through MoS₂/C microspheres, but also minimizes the influence of pulverization and aggregation of MoS₂ nanosheets during repeated sodiation and desodiation.     

Si/SiO2和SiNx/SiO2多层膜的室温光致发光

采用射频磁控溅射法,制备了纳米Si/SiO2和SiNx/SiO2多层膜,得到强的可见光致发光,利用傅里叶红外吸收(FTIR)谱和光致发光(PL)谱,对其发光特性进行了研究,在374 nm和712 nm左右观察到强发光峰.用量子限制-发光中心(QCLC)模型解释了其可能的发光机制,认为发光可能源自于SiOx界面处的缺陷发光中心.建立了发光的能隙态(EGS)模型,认为440 nm和485 nm的发光源于N-Si-O和Si-O-Si缺陷态能级.     

Superior Rate Mesoporous Carbon Sphere Array Composite via Intercalation and Conversion Coupling Mechanisms for Potassium-Ion Capacitors

Carbonaceous materials have been usually adopted as the anode for high energy density potassium-ion hybrid capacitors (KICs) owing to their low voltage plateau, high conductivity, and excellent electrochemical compatibility. The improvements of their specific capacity and sluggish intercalation mechanism are still challenges to further boost the energy density of KICs while maintaining high power density and long cycle life. Herein, a N-doped mesoporous carbon sphere array composite is developed by a dual-templates method. The N-doped carbon sphere array with interpenetrated macro- and meso-pores facilitates the fast electron transport and rapid K⁺ diffusion. The uniformly introduced Co₃O₄ nanoparticles (NPs) confined in the array enable a kinetically boosted conversion reaction for excess and fast K⁺ storage. The partially oxidized Co NPs can efficiently enhance the conductivity of the entire composite. By introducing this optimized conversion capacity from encapsulated Co₃O₄ NPs, the composite with intercalation and conversion coupling mechanisms displays superior capacity and cycle life. The assembled KICs exhibit high energy/power densities (148 Wh kg⁻¹/124 W kg⁻¹) and great cycling performance (94% after 5000 cycles, 0.5 A g⁻¹). This promising strategy demonstrates an example for carbonaceous composite anode with synergistic K⁺ storage hybrid mechanism toward high performance KICs.     

Battery Performance and Photocatalytic Activity of Mesoporous Anatase TiO2 Nanospheres/Graphene Composites by Template‐Free Self‐Assembly

Nanosized mesoporous anatase TiO₂ particles have important applications in high‐performance lithium ion batteries and efficient photocatalysis. In contrast to the conventional synthesis routes where various soft or hard templates are usually employed, the direct growth of uniform mesoporous anatase TiO₂ nanospheres on graphene sheets by a template‐free self‐assembly process is presented. Compared to the conventional mesoporous anatase particles consisting of polycrystalline TiO₂, the microstructure of obtained mesoporous anatase nanospheres on graphene sheets is single‐crystal‐like. The growth mechanism, lithium ion battery performance, and photocatalytic activity of the resultant mesoporous anatase TiO₂ nanospheres/graphene composites are thoroughly investigated. In comparison to the reference TiO₂, the composite shows substantial improvement in lithium specific capacity from 1 C to 50 C, and photocatalytic removing organic pollutant and hydrogen evolution. More strikingly, the specific capacity of the composite at the rate of 50 C is as high as 97 mA h g^?1, 6 times higher than that of the reference TiO₂.     

“Brain‐Coral‐Like” Mesoporous Hollow CoS2@N‐Doped Graphitic Carbon Nanoshells as Efficient Sulfur Reservoirs for Lithium–Sulfur Batteries

Hollow carbon materials are considered promising sulfur reservoirs for lithium–sulfur batteries owing to their internal void space and porous conductive shell, providing high loading and utilization of sulfur. Since the pores in carbon materials play a critical role in the infusion of sulfur, access of the electrolyte, and the passage of lithium polysulfides (LPSs), the creation and tuning of hierarchical pore structures is strongly required to improve the electrochemical properties of sulfur/porous carbon composites, but remains a major challenge. Herein, a “brain‐coral‐like” mesoporous hollow carbon nanostructure consisting of an in situ‐grown N‐doped graphitic carbon nanoshell (NGCNs) matrix and embedded CoS₂ nanoparticles as an efficient sulfur host is presented. The rational synthetic design based on metal–organic framework chemistry furnishes unusual multiple porosity in a carbon scaffold with a macrohollow in the core and microhollows and mesopores in the shell, without the use of any surfactant or template. The CoS₂@NGCNs/S composite electrode facilitates high sulfur loading (75 wt%), strong adsorption of LPSs, efficient reaction kinetics, and stable cycle performance (903 mAh g^?1 at 0.1 C after 100 cycles), derived from the synergetic effects of the dual hollow features, chemically active CoS₂, and the conductive and mesoporous N‐doped carbon matrix.     

2D Thin Nanoflakes Assembled on Mesoporous Carbon Nanorods for Enhancing Electrocatalysis and for Improving Asymmetric Supercapacitors

Carbon nanomaterials are of great interest as the advanced supports of electrochemical active materials to enhance their performances, however, little knowledge has been put into understanding whether the pores of carbon nanomaterials as supports can tune the performance of energy storage and conversion devices due to the lack of methods for making porous carbon nanomaterials. Herein, this study demonstrates the use of 1D ordered mesoporous carbon nanorods (OMCRs) with high surface area as a new class of supports for 2D ultrathin MoS₂ and MnO₂ nanoplates to create the interesting hierarchical nanohybrids (MoS₂@OMCRs and MnO₂@OMCRs), respectively. With the significant role of OMCRs in optimizing the electron and charge transportation, MoS₂@OMCRs exhibits remarkable activity for catalyzing hydrogen evolution reaction with a low onset overpotential of 105 mV and low Tafel slope of 40 mV dec^?1, much better than those of MoS₂@ carbon nanofibers. Significantly, the asymmetric supercapacitor based on MnO₂@OMCRs as anode and OMCRS as cathode displays a maximum specific capacitance up to 100 F g^?1 at 0.2 A g^?1 and a high energy density of 55.2 W h kg^?1 at the power density of 200 W kg^?1 within a wide operating voltage of 2.0 V. The present work highlights the important role of the mesoporous carbon support in achieving the advanced energy storage and conversion.