分类： 材料科学 >> 材料化学 提交时间： 2022-10-19 合作期刊: 《桂林电子科技大学学报》
摘要： 在固相烧结制备单相Sr2Bi2O5 的基础上,利用化学沉淀法制备了一系列CdS/Sr2Bi2O5 复合光催化材料来解决环境污染中的有机污染物问题。采用XRD、SEM、TEM、EDS和XPS进行了复合光催化剂的表征,通过降解亚甲基蓝评估其光催化性能。实验结果表明,CdS/Sr2Bi2O5 复合光催化剂由CdS和Sr2Bi2O5 两相组成,形貌为团聚状的Sr2Bi2O5 颗粒并附着在不规则的CdS颗粒上,两相表面紧密接触在一起,形成明显的界线,相互耦合形成异质结;当CdS/Sr2Bi2O5 摩尔比为1/1时,可见光光催化性能最好,40 min降解亚甲基蓝的效率达95%。进一步循环测试发现,复合光催化剂具有良好的稳定性。显著改善的光催化性能主要归因于复合光催化剂中在CdS与Sr2Bi2O5 之间形成了异质结,在加快光生电子空穴对分离的同时,还有效抑制了光生电子空穴对的复合。
分类： 材料科学 >> 材料化学 提交时间： 2018-01-27
摘要： 生物矿化领域的研究者普遍接受珍珠层板片是由非晶质碳酸钙(ACC)纳米颗粒相变而成。然而，这些纳米颗粒在三维空间是如何排列的及如何相变的仍未清楚。本文首次报道了一种新类型不成熟板片，即“枝晶状板片”。这种板片发育在翡翠贻贝珍珠层中。通过与颗粒状板片形貌进行对比，我们发现ACC纳米颗粒通常自组装成垂直的团簇且相变成垂直定向的文石小晶体。这种小晶体与无机成因的文石晶体的平衡形状相同。最重要的是，我们首次发现文石板片与层间有机膜(ILM)呈高的接触角(99-126度)。这表明ILM对ACC纳米颗粒是非润湿的。这种非润湿性可能对珍珠层的形貌成因有重要影响。
分类： 材料科学 >> 材料化学 提交时间： 2017-11-01
摘要： Doping additional ions into semiconductor is a potential strategy to modify the electronic structure of semiconductor materials. By using a highly reactive colloidal Cu clusters as doping precursor, we present here the successful doping of Cu ions into TiO2 nanocrystalline that simultaneously transformed from amorphous anodic TiO2 nanotubes during a dissolution and recrystallization process. The Cu-doped TiO2 nanoparticles (Cu-TNPs) film was characterized by X-ray diffraction, scanning and transmission electron microscopy and Raman spectroscopy. The Cu-TNPs show a rugby-like shape with exposed active {101}, {001} facets and the long-axis parallel to [001] lattice direction. The substitutional Cu2+ ions dopants in TiO2 nanocrystals caused the swelling of the crystalline unit cell. Such efficient doping design facilitate the improvement of nanostructured TiO2 as a potential biosensor for glucose molecules.
分类： 材料科学 >> 材料化学 提交时间： 2017-11-01
摘要： We report a simple and environment-friendly route to prepare platinum/reduced graphene oxide (Pt/rGO) nanocomposites (NCs) with highly reactive MnOx colloids as reducing agents and sacrificial templates. The colloids are obtained by laser ablation of a metallic Mn target in graphene oxide (GO)-containing solution. Structural and morphological investigations of the as-prepared NCs revealed that ultrafine Pt nanoparticles (NPs) with an average size of 1.8 (± 0.6) nm are uniformly dispersed on the surfaces of rGO nanosheets. Compared with commercial Pt/C catalysts, Pt/rGO NCs with highly electrochemically active surface areas show remarkably improved catalytic activity and durability toward methanol oxidation. All of these superior characteristics can be attributed to the small particle size and uniform distribution of the Pt NPs, as well as the excellent electrical conductivity and stability of the rGO catalyst support. These findings suggest that Pt/rGO electrocatalysts are promising candidate materials for practical use in fuel cells.
分类： 材料科学 >> 材料化学 提交时间： 2017-11-01
摘要： Morphology control and impurity doping are two widely applied strategies to improve the electrochemical performance of nanomaterials. Herein, we report an environmentally friendly approach to obtain Co-doped Ni(OH)2 nanosheet networks using a laser-induced cobalt colloid as a doping precursor followed by an aging treatment in a hybrid medium of nickel ions. The shape and specific surface area of the doped Ni(OH)2 can be successfully adjusted by changing the concentration of sodium thiosulfate. Furthermore, a Co-doped Ni(OH)2 nanosheet network was further converted into Co-doped NiO with its pristine morphology retained via facile thermal decomposition in air. The structure and electrochemical performance of the as-prepared samples are investigated with scanning and transmission electron microscopy, energy dispersive x-ray analysis, x-ray diffraction, Fourier transform infrared spectroscopy, the nitrogen adsorption-desorption isotherm technique, and electrochemical measurements. The Co-doped Ni(OH)2 electrode shows an ultrahigh specific capacitance of 1421 F/g at a current density of 6 A/g, and a good retention level of 76% after 1000 cycles, in sharp contrast with only a 47% retention level of the pure Ni(OH)2 electrode at the same current density. In addition, the Co-doped NiO electrode exhibits a capacitance of 720 F/g at 6 A/g and 92% retention after 1000 cycles, which is also superior to those values for relevant pure NiO electrodes. The Co2+ partially substitutes for Ni2+ in the metal hydroxide and oxide, resulting in an increase of free holes in the valence band, and, therefore, enhancement of the p-type conductivity of Ni(OH)2 and NiO. Moreover, such novel mesoporous nanosheet network structures are also able to enlarge the electrode-electrolyte contact area and shorten the path length for ion transport. The synergetic effect of these two results is responsible for the observed ultrahigh pseudocapacitor performance.
分类： 材料科学 >> 材料化学 提交时间： 2017-10-31
摘要： Incorporating noble metal nanoparticles on the surface or inner side of semiconductors to form a hybrid nanostructure is an effective route to improve the gas sensing performance of these semiconductors. In this study, we present novel Au-decorated ZnO nanospheres (Au-ZnO NSs) obtained by laser irradiation of liquids. Structural characterization indicated that the Au-ZnO NSs consisted of single crystalline ZnO NSs with few Au nanoparticles decorated on their surfaces and abundant encapsulated Au nanoparticles with relatively small sizes. Laser irradiation-induced heating–melting–evaporating processes are responsible for the formation of unique Au-ZnO NSs. Gas sensing properties of the Au-ZnO NSs, as gas sensing materials, were investigated and compared with those of pure ZnO NSs. The former showed lower working temperature, higher sensitivity, better selectivity, and good reproducibility. The response values of Au-ZnO NSs and pure ZnO NSs sensors to ethanol of 100 ppm were 252 and 75 at working temperature of 320 °C and 360 °C, respectively. The significant enhancements in gas sensing performance should be attributed to the electronic sensitization induced by the depleted layers between encapsulated Au nanoparticles and ZnO and chemical sensitization originating from the catalytic effects of Au nanoparticles decorated on the surfaces that dissociated molecular oxygen.
分类： 材料科学 >> 材料化学 提交时间： 2017-10-31
摘要： A general and straightforward strategy was developed for fabricating transition metal carbide (TMC)/carbon (C) core/shell nanospheres (NSs) by laser ablation of transition metals in acetone/ethanol liquid. Various TMC/C core/shell NSs such as TaC/C, NbC/C, HfC/C, and MoC/C core/shell NSs were successfully fabricated, highlighting the generality of this method. Crucially, this approach is green, facile, catalyst-free, and especially can be operated under ambient environments. Interestingly, all of the as-synthesized TMCs in the NS cores showed a cubic phase and structures similar to that of NaCl-type. The cores were further encapsulated by amorphous carbon shell with different thickness. As an example of the functional properties of these compound materials, the TaC/C core/shell NSs obtained were investigated as a supercapacitor electrode, which showed a large specific capacitance, excellent rate capability and remarkable cycling ability, revealing that the NSs could be used as new electrode materials for electrochemical energy storage. The photoluminescence of TaC/C core/shell NSs exhibited strong emission under the specific excitation wavelength at room temperature, showing potential biomedical applications due to the good biocompatibility of carbon shell. Besides, the basic physical and chemical reactions involved in the unique formation mechanism under highly nonequilibrium states induced by ultrafast laser ablation were discussed.
分类： 材料科学 >> 材料化学 分类： 材料科学 >> 金属与冶金 提交时间： 2017-08-15
摘要： All-vanadium redox flow battery (VRFB) is a large-scale electrochemical energy storage technology with numerous potential applications because of its inherent safety and long service life. In previous years, a novel mixed-acid electrolyte system, vanadium electrolytes with mixture of sulfuric acid and hydrochloric acid, has been developed by the Pacific Northwest National Laboratory (PNNL) to increase vanadium solubility, which can effectively raise the electrolyte energy density from 25 Wh/L to 40 Wh/L. To further improve mixed-acid VRFBs, in present work, high purity mixed-acid electrolytes were prepared using a novel direct dissolution – electrochemical reduction process from high purity vanadium oxytrichloride (VOCl3). And the purity and electrochemical properties were investigated, comparing with common mixed-acid electrolytes and regular sulfate electrolytes prepared from metallurgical grade vanadium pentoxide. It was found that the novel process demonstrated a great potential for the low cost and high efficiency production of high purity electrolytes with excellent electrochemical properties for mixed-acid VRFBs. Comparing the traditional high purity electrolytes preparation process, the present novel method will dramatically cut the cost by more than 90 percent, which will considerably facilitate the commercial application of high performance and high density VRFBs.
点击量
点击量
下载量
评论
待评议
