自掺杂型锑氧化物材料的制备、表征及其对Sr(Ⅱ)的吸附性能

90Sr是核电站放射性废液中需要重点去除的核素之一,水合锑氧化物Sb2O5·mH2O可以在酸性条件下选择性吸附脱除90Sr.本文在以醇为溶剂的无水体系中,以化学性能较稳定且毒性低的SbCl3为原料,以紫外线照射辅助双氧水氧化及控制水解两步法制备出自掺杂型锑氧化物Sb(Ⅲ)/Sb2O5.文中采用X射线光电子能谱(XPS)、X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱对材料结构进行结构表征,并采用批量实验方法研究不同Sb(Ⅲ)/Sb(total)比例与Sr(Ⅱ)吸附性能的相关性,以及溶液pH值对Sr(Ⅱ)吸附性能的影响.实验结果表明:Sb(Ⅲ)可在较大的比例范围内共存于立方烧绿石型Sb2O5晶格内,形成良好的固溶体Sb(Ⅲ)/Sb2O5;制备过程中通过控制醇溶剂的类型、氧化剂的添加方式以及两步反应温度,可以获得具有不同氧化率,即不同Sb(Ⅲ)/Sb(total)比例的Sb(Ⅲ)/Sb2O5材料;其中Sb(Ⅲ)/Sb(total)比例为49.8%的锑氧化物材料吸附性能最好,在纯水体系下对Sr(Ⅱ)的分配系数为6.6×107mL·g-1,在pH=3-13范围内对Sr(Ⅱ)具有良好的吸附性能,并且在本文实验条件下,Sr(Ⅱ)在锑氧化物材料上的吸附更好地符合Langmuir吸附模型.     

离子色谱-双阳极电化学氢化物发生-原子荧光光谱法测定当归中Sb(Ⅲ)和Sb(Ⅴ)

采用离子色谱-双阳极电化学氢化物发生-原子荧光光谱法分析锑形态,实验采用pH 6.50 浓度均为50 mmol/L的(NH2)2HPO4和酒石酸混合溶液为离子色谱流动相,5 min内实现Sb(Ⅴ)、 Sb(Ⅲ)的基线分离,Sb(Ⅴ)、 Sb(Ⅲ)色谱峰面积的相对标准偏差是4.0%、 2.3%,100 μL进样时得到的检出限分别为5.39、 5.42 μg/L(S/N＝3),方法可用于实际样品中的锑化合物形态的分析测定.     

生物分子辅助溶剂热合成硫化锑纳米棒

以SbCl3和L-胱氨酸为反应原料,采用溶剂热法在170℃反应12h,制得硫化锑(Sb2S3)纳米棒.X射线衍射(XRD)、能量分散光谱(EDS)和X射线光电子能谱(XPS)研究表明所得产物为典型的Sb2S3正交结构.场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)研究显示,Sb2S3纳米棒长为3～6μm,平均直径约为150nm.讨论了不同反应时间对Sb2S3的形成及其形貌的影响,并根据实验结果对所合成的一维纳米棒可能的形成机理进行了简单的探讨.     

无机-有机杂化层状锑硫化合物的溶剂热合成与结构

用溶剂热法合成了有机杂化层状锑硫化合物[C3H7NH3]2Sb4S7,并利用单晶X-射线衍射测定了其晶体结构。该化合物为三斜晶系,Pī空间群。晶胞参数:a=7.0098(10),b=11.9710(14),c=13.6685(17),α=115.244(6)°,β=98.671(9)°,γ=92.413(13),°V=1018.3(2)3,Z=2,Mr=831.71 g.mol-1,(=5.984 mm-1,F(000)=772,偏差因子R1=0.0334,wR2=0.0766。该化合物由质子化正丙胺离子[C3H7NH3] 和二维阴离子[Sb4S7]n2n-组成,[Sb4S7]n2n-二维离子由3个SbS3三角锥和1个SbS4变形四面体单元连接而成,[C3H7NH3] 离子位于无机阴离子层之间,形成三明治夹心式结构,[C3H7NH3] 的-NH3 基团与无机阴离子层的S原子形成N-H…S氢键作用。     

氧化石墨烯改性ZnO/CeO2复合纳米材料的制备及其紫外屏蔽性能研究

以六水硝酸锌、六水硝酸铈、氧化石墨烯为原料,采用溶胶凝胶法制备了氧化石墨烯(GO)改性ZnO/CeO_2复合纳米紫外屏蔽剂。采用X射线衍射(XRD)、扫描电镜(SEM)、傅立叶变换红外光谱(FTIR)、紫外可见分光光度计(UV-Vis)等测试手段对产物的结构、组成及形貌进行表征,研究了氧化铈与氧化锌摩尔比、GO投入量、屏蔽剂用量以及pH值对复合纳米材料紫外屏蔽性能的影响,探索了氧化石墨烯改性ZnO/CeO_2复合纳米的最佳制备条件。结果表明:氧化石墨烯改性ZnO/CeO_2复合纳米材料中GO、CeO_2、ZnO的平均粒径分别为8. 3、15. 4、37. 5 nm。当pH 6. 0、氧化铈与氧化锌摩尔比为4∶1、GO投入量为2. 0g、屏蔽剂用量为0. 06 g/L时,紫外屏蔽性能强弱顺序为:氧化石墨烯改性ZnO/CeO_2复合纳米材料 GOZnO/CeO_2复合纳米材料 CeO_2 ZnO。     

OTS自组装单层膜诱导生长Sb_2S_3薄膜及其生长机理

在接近室温的水溶液中通过采用OTS-自组装单分子层制备了Sb2S3薄膜。利用X-射线粉末衍射(XRD)、扫描电子显微镜(SEM)、X-射线能量色散谱(EDS)和紫外-可见分光光度计(UV-Vis)对Sb2S3薄膜的结构、形貌和光学性能进行了表征。结果表明,低温下所制备的薄膜为非晶态结构,当薄膜在空气中200~300℃热处理1h时,非晶态薄膜转化成具有正交晶相结构的多晶结构。光学性能测试表明,沉积的Sb2S3薄膜和在空气中200℃热处理1h后Sb2S3薄膜的能带值分别为2.05和1.78eV。功能化OTS自组装单分子层(SAMs)在Sb2S3薄膜的生长过程中起到了诱导生长的作用。通过实验结果,进一步分析了Sb2S3薄膜的形成机理。     

层状多硫代锑(Ⅲ)酸镉(Ⅱ)化合物(1,4-DABH2)Cd2Sb2S6的溶剂热合成与表征

利用溶剂热方法合成了层状多硫代锑髥酸镉髤化合物(1,4-DABH2)Cd2Sb2S6(1)(1,4-DAB=1,4-丁二胺),并通过红外光谱、热重分析对其进行了表征,用X-射线衍射测定了化合物的单晶结构。单晶解析表明,化合物属正交晶系,Cmca空间群,Mr=750.77,a=0.860 3(5)nm,b=0.898 7(6)nm,c=2.273(2)nm,V=1.758(2)nm3,Z=4,λ=0.071 073 nm,R=0.032,wR=0.106 7。晶体结构中含有六元环的Cd2SbS3和八元环的Cd2Sb2S4的阴离子网络层状[CdSbS3]nn-,双质子化的有机阳离子在阴离子层之间以氢键N-H…S形式连接。另外紫外-可见漫反射光谱研究表明,化合物为半导体。     

热剥离法制备石墨烯纳米片对Pb2+和Cd2+的吸附

石墨粉氧化后,在氮气气氛下,快速高温剥离制得石墨烯纳米片。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(HRTEM)、拉曼(Raman)光谱、傅里叶变换红外(FT-IR)光谱和氮气吸附-脱附等分析手段对石墨烯样品进行了表征。这些分析测试结果显示:石墨烯样品主要由很薄的1-4层石墨组成,呈褶皱状态,比表面积为628.5 m²·g^-1。研究了石墨烯吸附水溶液中的Pb²⁺和Cd²⁺的pH值、吸附时间、吸附温度和金属离子初始浓度等影响因素, Pb²⁺和Cd²⁺的最大吸附量分别为460.20和72.39 mg·g^-1。结果表明,热剥离法制得的高质量石墨烯纳米片可以作为一种高效的从水中去除Pb²⁺和Cd²⁺的吸附材料。     

含二胺基-锑配体的高自旋亚铁配合物:合成、表征及其与有机叠氮和重氮化合物的反应

通过PhSbCl_2与2 equiv.2-(N-锂-N-(2',6'-二氯苯基)胺基)苯基锂的反应合成了二(2-(N-(2',6'-二氯苯基)胺基)苯基)苯基锑[H_2(~(dcp)N_2Sb)].利用H_2(~(dcp)N_2Sb)与[Fe(N(SiMe_3)_2)_2]_2的胺消除反应合成得到二胺基-锑配位的亚铁配合物[(κ~3-N,N,Sb~(dcp)N_2Sb)Fe(THF)](1).配合物1为首例高自旋型有机锑-铁配合物.配合物1与有机叠氮化合物RN_3[R=dcp(2,6-Cl_2C_6H_3)],Dipp(2,6-~iPr_2C_6H_3))反应生成二胺基-锑亚胺配位的亚铁配合物[(κ~3-N,N,N-~(dcp)N_2SbN~R)Fe(py)](R=dcp,2;R=Dipp,3).配合物1与重氮化合物反应生成二胺基-锑叶立德配位的亚铁配合物[(κ~3-N,N,C-~(dcp)N_2Sb C~(R1,R2))Fe(PMe_3)](R~1=H,R~2=CO_2Bu~t,4;R~1=Ph,R~2=CO_2Et,5).锑配体H_2(~(dcp)N_2Sb)和配合物1～5经元素分析、~1H NMR、溶液相磁化率、单晶X射线衍射等进行了表征.     

电化学氢化物发生原子荧光法测定环境样品中的锑

使用中性磷酸盐缓冲体系作为电解质,研究了锑化氢的电解生成情况. 结果发现,Sb(Ⅲ)的原子荧光光谱(AFS)响应信号强度比在酸性介质中提高了1倍,而Sb(Ⅴ)几乎没有响应信号,因此可以在此缓冲体系中进行价态分析,可消除酸性介质对电极的腐蚀,延长了电解池及电极的使用寿命,提高了信号的稳定性. 将传统的平板式电解池的螺丝密封改进为螺纹密封,使电解池安装时间从原来的20 min缩短为1 min,提高了电解池的密封性能. Sb(Ⅲ)的检出限为0.038 μg/L(3σ),相对标准偏差为3.9%(n=11). 分析了多种环境样品中的锑,结果满意.     

SbVO_4 based high capacity potassium anode: a combination of conversion and alloying reactions

As the key to optimizing potassium ion batteries’(PIBs)performance,the development of high capacity potassium anode is the footstone.Here,through a one-step solvothermal method,uniformly dispersed SbVO4 nanoparticles on the reduced graphene oxide nanosheets(SbVO4@RGO)were synthesized and used as PIBs anodes.SbVO4@RGO anode shows high capacity due to alloying and conversion reactions occur simultaneously in the cyclic process.The anode delivers a capacity as high as 447.9 mAh g^-1 at 100 mA g^-1.Besides,a cycling life of 500 cycles with small average capacity decay rate(only 0.106%per cycle)is also revealed.It was found in the initial discharge process,SbVO4 transforms into Sb and K3VO4.And in the following cycle Sb and K3VO4 simultaneously react with K+via the alloying/de-alloying and conversion reaction,respectively.The present study of SbVO4@RGO may provide insight for high performance alloying-based/conversion-based potassium anodes.     

分等级结构对锡氧化物负载Pt室温催化甲醛氧化性能的影响

甲醛是主要的室内空气污染物,气相中甲醛去除技术具有重要意义.常用的甲醛去除技术主要包括物理和化学吸附、光催化分解和热催化氧化,其中能在常温下进行的催化氧化最具发展和实用前景.能在室温下高效催化甲醛完全氧化的催化剂一般为负载型贵金属,如铂(Pt)、钯、金、银等.除了选择具有内在高活性的组分,通过提高贵金属分散度,增强贵金属-载体相互作用,增加载体的甲醛亲和性等方法也可提高甲醛催化分解活性.以上方法主要关注催化剂化学性质的改良;另一方面,催化剂的微观几何结构以及传质快慢对表观催化反应速率也有重要影响.近年来研究表明,分等级结构利于反应物在材料孔隙中的扩散输移,可大幅提高催化活性.因此,我们制备了具有分等级结构的花状锡氧化物(SnOx)负载的Pt纳米颗粒,并研究其室温下催化分解甲醛的性能.花状SnOx以氟化亚锡和尿素为原料,通过水热法制备;Pt通过浸渍、硼氢化钠还原法负载,制备Pt/SnOx催化剂.另外,对SnOx进行球磨处理破坏其分等级结构,制备g-SnOx及Pt/g-SnOx作为对照.通过场发射扫描电镜观察,制备的锡氧化物为具有分等级结构的花状微球,直径约1?m,由厚度约20 nm的花瓣状纳米片交错连接而成.X射线衍射(XRD)谱图对应四方相氧化亚锡(SnO,JCPDS 06-0395),但也观察到四方金红石相氧化锡(SnO2,JCPDS 41-1445)的微弱特征峰.高分辨透射电镜(HRTEM)仅观察到四方相SnO的晶格条纹.根据X射线光电子能谱(XPS)结果,在花状锡氧化物的表面,锡元素的氧化态为正四价.综合以上表征结果表明:制备的锡氧化物主体为SnO,由于表面被空气氧化,含有少量SnO2.通过透射电镜观察Pt/SnOx催化剂发现,直径2–3 nm的Pt纳米颗粒高度分散负载于SnOx纳米片表面;XPS结果表明,纳米颗粒中Pt的价态为0价,与HRTEM观测结果一致.甲醛分解测试采用静态测试系统,在体积为6 L的测试箱中加入一定浓度甲醛后开始反应,监测甲醛、二氧化碳(CO2)和一氧化碳(CO)浓度随时间的变化.结果表明,花状SnOx在室温下不具有催化甲醛氧化活性,仅能通过吸附作用去除少量甲醛;而负载0价金属态Pt纳米颗粒后,甲醛快速分解为CO2和水,且无CO生成.在初始浓度170 ppm条件下,反应1 h后,甲醛去除率达到87%.Pt/SnOx催化剂的高活性表明,金属态Pt是催化甲醛氧化的活性组分.经球磨处理后制备的Pt/g-SnOx,其催化活性远低于具有分等级结构的Pt/SnOx;后者的二级反应速率常数为前者的5.6倍,证明分等级结构能有效加速甲醛催化氧化分解.本研究结果对于高效分解室内甲醛材料的设计、制备提供了一种指导性的新思路.     

应用于氧还原反应的石墨烯-无定形碳核壳结构复合材料载铂催化剂(英文)

采用氯化法制备石墨烯-无定型碳复合材料(GNS@a-C),并用作质子交换膜燃料电池(PEMFC)氧还原反应Pt催化剂的载体.结果显示,所制Pt/GNS@a-C催化剂与传统商业催化剂Pt/C相比,有较好的活性和较高的稳定性:质量活性(0.121 A/mg)几乎是Pt/C(0.064 A/mg)的两倍.更重要的是,该新型催化剂加速4000圈后其电化学活性面积保留了最初的51%,与Pt/C的33%相比,前者有更好的电化学稳定性,显示它在PEMFC中将具有较好的应用潜力.     

Synergistic Hybrid Catalyst for Ethanol Detection: Enhanced Performance of Platinum Palladium Bimetallic Nanoparticles Decorated Graphene on Glassy Carbon Electrode

The present study highlights the first time use of hybrid synergy electrocatalysis to design a cost effective, non-enzymatic ethanol sensor. The nanohybrid has been synthesized by decorating platinum palladium bimetallic nanoparticles (Pt?PdNPs) on graphene nanosheets (G/Pt?PdNPs). Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, electrochemical measurements and UV-Vis spectrophotometry have been used to characterize the nanocomposite. An ethanol oxidation current of 332 μA was obtained with the use of G/Pt?PdNPs modified glassy carbon electrode (GCE) that is 167 times higher than that of bare GCE in cyclic voltammetry studies with a potential scan rate of 50 mV/s in 0.1 M NaOH as the supporting electrolyte. Chronoamperometry studies have shown a distinct increase in the current for increasing concentration of ethanol with a wide range of linearity extending from 5 mM to 3 M and a detection limit of 1 mM with the use of G/Pt?PdNPs. Quantum mechanical modeling using density functional theory was used to arrive at the minimization energies of G/Pd, G/Pt and G/Pt?Pd in the presence and absence of ethanol. The improved catalytic activity of G/Pt?PdNPs nanocomposite for ethanol detection is on account of the cooperative effects of Pt and PdNPs, coupled with the high conducting nature of graphene.     

石墨烯载Pt纳米粒子的原位还原制备及氧还原电催化性能

采用改进的化学氧化还原法(Hummers法)氧化鳞片石墨, 再超声振荡剥离得到氧化石墨烯(GO)水溶液. 通过聚二烯丙基二甲基氯化铵(PDDA)分子对GO表面功能化, 由于带正电荷的PDDA分子功能化的GO与带负电荷的^2-离子间的静电作用, 使Pt离子组装到GO表面, 再通过原位还原被束缚的Pt离子, 同时GO被还原成石墨烯片(GNs), 得Pt/PDDA-GNs催化剂. 相对空白GNs负载的Pt纳米粒子和商业化Pt/C(JM), Pt/PDDA-GNs催化剂有较高的氧还原活性和稳定性. 前者可归因于Pt颗粒尺寸细小和分散度较高, 后者是由于PDDA分子与Pt原子间的电子作用及对Pt颗粒的钉扎作用, 从而减缓了Pt的氧化和迁移.     

Three-dimensional flower-like nickel oxide supported on graphene sheets as electrode material for supercapacitors

Dispersed three-dimensional (3D) flower-like nickel oxide on graphene sheets was synthesized by incorporating a facile hydrothermal process with a thermal treatment process. The possible growth mechanism of 3D flower-like NiO is discussed. When used as electrode materials for supercapacitors, the resultant composite exhibits a specific capacitance of 346F/g (1.5A/g), a good rate performance and cycle stability in 2?M KOH. NiO in the composite could provide a specific capacitance as high as 778.7F/g, compared to that of bare NiO of only 220F/g. The functional features of unique 3D flower-like NiO morphology, high conductivity of graphene sheets and its protective effect to the structure of NiO result in an improved electrochemical performance.     

A study of novel macrocyclic copper complex/graphene‐based composite materials for counter electrodes of dye‐sensitized solar cells

In this study, a newly synthesized macrocyclic copper complex, [Cu(C₁₀H₂₀N₈)(C₄H₈N₄)](BF₄)₂, was used for a reaction with graphene oxide. Macrocyclic copper complex/graphene‐based composite materials were prepared and applied to the counter electrodes (CEs) of dye‐sensitized solar cells (DSSCs). As the level of the macrocyclic copper complex increased, the catalytic sites on the surface of the CE increased. The results showed that the device efficiency of the composite GO/Cu (1:10) CE was 7.61%, which was better than that of the Platinum (Pt) CE (7.04%). The device efficiency of the DSSC was enhanced effectively because the electrocatalytic activity of the CE was enhanced, and the interface impedance of the device was reduced. Therefore, the macrocyclic copper complex/graphene‐based composite materials may have the potential to replace traditional Pt to increase efficiency and reduce the fabrication cost of DSSCs.     

Sonochemical synthesis of graphene oxide supported Pt–Pd alloy nanocrystals as efficient electrocatalysts for methanol oxidation

Pt–Pd bimetallic nanoparticles supported on graphene oxide (GO) nanosheets were prepared by a sonochemical reduction method in the presence of polyethylene glycol as a stabilizing agent. The synthetic method allowed for a fine tuning of the particle composition without significant changes in their size and degree of aggregation. Detailed characterization of GO-supported Pt–Pd catalysts was carried out by transmission electron microscopy (TEM), AFM, XPS, and electrochemical techniques. Uniform deposition of Pt–Pd nanoparticles with an average diameter of 3 nm was achieved on graphene nanosheets using a novel dual-frequency sonication approach. GO-supported bimetallic catalyst showed significant electrocatalytic activity for methanol oxidation. The influence of different molar compositions of Pt and Pd (1:1, 2:1, and 3:1) on the methanol oxidation efficiency was also evaluated. Among the different Pt/Pd ratios, the 1:1 ratio material showed the lowest onset potential and generated the highest peak current density. The effect of catalyst loading on carbon paper (working electrode) was also studied. Increasing the catalyst loading beyond a certain amount lowered the catalytic activity due to the aggregation of metal particle-loaded GO nanosheets.     

Mesoporous PtPb Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution and Ethanol Oxidation

Using a one-pot hydrothermal method with ethylenediamine, we have synthesized mesoporous PtPb nanosheets that exhibit exceptional activity in both hydrogen evolution and ethanol oxidation. The resulting PtPb nanosheets have a Pt-enriched structure with up to 80 % atomic content of Pt. The synthetic method generated a significant mesoporous structure, formed through the dissolution of Pb species. These advanced structures enable the mesoporous PtPb nanosheets to achieve a current density of 10 mA cm⁻² with an extreme low overpotential of 21 mV for hydrogen evolution under alkaline conditions. Furthermore, the mesoporous PtPb nanosheets exhibit superior catalytic activity and stability for ethanol oxidation. The highest catalytic current density of PtPb nanosheets is 5.66 times higher than that of commercial Pt/C. This research opens up new possibilities in designing mesoporous, two-dimensional noble-metal-based materials for electrochemical energy conversion with excellent performance.     

Durability investigation of graphene-supported Pt nanocatalysts for PEM fuel cells

We report graphene nanosheets as a durable alternative support material for Pt nanoparticle catalysts for oxygen reduction in proton exchange membrane (PEM) fuel cells and compared them to XC-72. The materials were characterized by X-ray diffraction and transmission electron microscopy. Electrochemical surface oxidation of XC-72 and graphene, and of Pt/XC-72 and Pt/graphene has been compared following treatments for up to 120 h. The electrochemical performance of the specimens was evaluated by cyclic voltammetry and linear sweep voltammetry at different surface oxidation time intervals. Electrochemical measurements indicate that the graphene exihibits greatly enhanced electrochemical durability. It is suggested that graphene nanosheet is a promising, low-cost, and durable electrocatalyst support for oxygen reduction in the PEM fuel cell.