CeO_(2)/CuO气体传感器的制备及其正丁醇的气敏性能

以乙酸铜、乙酸铈有机金属盐为前驱体,以碳酸钠为沉淀剂,通过水热法制备了不同Ce元素与Cu元素的摩尔百分比的CeO_(2)/CuO双金属氧化物气体敏感材料,并对所制备的材料进行了扫描电子显微镜(SEM)形貌表征,结果显示CeO_(2)/CuO复合材料为直径6~8μm的空心微球。将制备的CeO_(2)/CuO复合材料涂覆于陶瓷管上制成旁热式气体传感器。气敏测试结果表明,Ce元素与Cu元素的摩尔百分比为3%的CeO_(2)/CuO复合材料传感器对正丁醇气体有着良好的气敏性能,其最佳工作温度为200℃,响应度为纯CuO的1.5倍。此外,该传感器还有着优异的重复性、响应/恢复时间(约5s/15s)。

CeO_(2)-C复合空心球改性硫正极的电化学性能

本文以酚醛树脂(APF)和六水合硝酸铈(Ce(NO_(3))_(3)·6H_(2)O)为原料,采用无溶剂模板法制备CeO_(2)-C复合空心球,并通过X射线衍射仪、扫描电子显微镜、透射电子显微镜、傅里叶红外光谱等测试方法对其进行表征。以商业化导电碳黑作为硫载体,将CeO_(2)-C复合空心球作为添加剂改性硫正极材料,并进行循环伏安(CV)、恒电流充放电、电化学阻抗(EIS)等电化学性能测试。结果表明:CeO_(2)-C复合空心球改性后的硫正极材料具有较好的电化学性能,其在0.2C下的初始放电容量可达到1 125 mAh/g;在1C下循环500圈,每圈的容量损失率仅为0.083%。以商业化导电碳黑作为硫载体,通过添加少量CeO_(2)-C复合空心球改性剂制备硫正极,能够在不改变目前锂硫电池制备工艺的前提下,有效提升锂硫电池的电化学性能,显示出巨大的应用潜力。

Resistive-type sensors based on few-layer MXene and SnO_(2)hollow spheres heterojunctions:Facile synthesis,ethanol sensing performances

High-performance and low-cost gas sensors are highly desirable and involved in industrial production and environmental detection.The combination of highly conductive MXene and metal oxide materials is a promising strategy to further improve the sensing performances.In this study,the hollow SnO_(2)nanospheres and few-layer MXene are assembled rationally via facile electrostatic synthesis processes,then the SnO_(2)/Ti_(3)C_(2)T_(x)nanocomposites were obtained.Compared with that based on either pure SnO_(2)nanoparticles or hollow nanospheres of SnO_(2),the SnO_(2)/Ti_(3)C_(2)T_(x)composite-based sensor exhibits much better sensing performances such as higher response(36.979),faster response time(5 s),and much improved selectivity as well as stability(15 days)to 100ppm C2H5OH at low working temperature(200°C).The improved sensing performances are mainly attributed to the large specific surface area and significantly increased oxygen vacancy concentration,which provides a large number of active sites for gas adsorption and surface catalytic reaction.In addition,the heterostructure interfaces between SnO_(2)hollow spheres and MXene layers are beneficial to gas sensing behaviors due to the synergistic effect.

Enhanced photocatalytic activity and mechanism of CeO_(2) hollow spheres for tetracycline degradation

Recently, researchers have focused on designing and fabricating highly efficient catalysts for photocatalytic organic pollutant removal. Herein, CeO_(2) hollow spheres were prepared through a simple template method followed by calcination at different temperatures for the tetracycline(TC) degradation under simulated solar light illumination. With a calcination temperature ranging from400 to 800 ℃, the as-prepared CeO_(2) hollow structure annealed at 600 ℃(C_(600)) exhibited the best degradation performance with a degradation rate constant of0.066 min-1, which was about six and five times higher than those of the uncalcined sample(C_(0)) and the sample calcined at 800 ℃(C_(800)), respectively. Moreover, sample C_(600)was also superior to the CeO_(2) solid particle photocatalyst. The characterisation results showed that the improved photocatalytic performance was mainly ascribed to the synergistic effect of large specific surface areas, high crystallisation and excellent light scattering ability. Furthermore, the results of active species trapping experiments demonstrated that the superoxide anion(·O_(2)^(-)) radical and hole(h^(+)) played dominant roles in TC degradation. Subsequently, the possible TC degradation pathways and photocatalytic mechanism of CeO_(2) hollow spheres were proposed on the basis of high-performance liquid chromatography–mass spectrometry analysis, main active species and band edge positions of CeO_(2). The results of this study provide a basis for designing and exploring hollow structure catalysts for energy conversion and environmental remediation.

Mesoporous CeO_(2)-C hybrid spheres as efficient support for platinum nanoparticles towards methanol electrocatalytic oxidation

The development of direct methanol fuel cells(DMFCs) is partially limited by the poor kinetics of methanol oxidation reaction(MOR) at the anode side.It was reported that the interaction between Pt and CeO_(2) enhances the electrocatalytic performance of Pt catalyst for MOR.In this work,a hybrid material(CeO_(2)-C) composed of CeO_(2) and carbon was successfully prepared by a simple hydrothermal method followed by calcination in inert atmosphere.The hierarchically porous nanostructure and especially good electronic conductivity of CeO_(2)-C make it an excellent support for Pt particles for application in electrocatalytic process.TEM investigation reveals that triple-phase interface of Pt,carbon and CeO_(2) forms in Pt/CeO_(2)-C catalyst.Performance of the as-prepared catalyst for MOR was studied in alkaline medium.The Pt/CeO_(2)-C catalyst shows superior catalytic performance for MOR compared with Pt/CeO_(2) and the physical mixture of Pt/CeO_(2) and acetylene black(Pt/CeO_(2)+C).The significantly improved performance can be attributed to the synergetic effect between Pt particles and CeO_(2)-C support,and the better conductivity of CeO_(2)-C.This study provides a possible method to expand the application potential of CeO_(2) materials in MOR,and may also be used in other electrocatalytic process.

SiO_(2)空心球及SiO_(2)/TiO_(2)复合空心球的制备与性能研究

空心球材料是一种理想的保温结构,其极大降低了表观密度和空气对流换热,增加了热反射,降低了热导系数。因此,空心球材料在建筑、涂料、装潢等领域有着较大的应用前景。采用模板法以聚苯乙烯微球为模板,制备了纳米级SiO_(2)空心球,再以此SiO_(2)空心球为模板,采用包裹沉淀法制备了SiO_(2)/TiO_(2)复合空心球。结果显示:SiO_(2)空心球粒径为150 nm左右,球壳厚度小于10 nm;SiO_(2)/TiO_(2)复合空心球粒径为150 nm左右,球壳厚度约为20 nm,TiO_(2)主要存在于球壳表面。SiO_(2)空心球的太阳光反射率可达80%,导热系数在0.050 W·m^(-1)·K^(-1)~0.054 W·m^(-1)·K^(-1)之间。SiO_(2)/TiO_(2)复合空心球的太阳光反射率在可见-近红外波段可达90%,可见光波段可达95%,导热系数在0.050 W·m^(-1)·K^(-1)~0.052 W·m^(-1)·K^(-1)之间。