自组装TiO_2分级结构材料的制备及性能研究

采用水热法合成了梭形TiO_2分级结构材料,运用扫描电镜(SEM)、X射线衍射(XRD)对其形貌、结构进行了表征和分析,考察了水热温度、乙酸加入量对TiO_2样品的影响,并研究了其光催化性能。结果表明,所制备TiO_2分级结构材料为锐钛矿相,是由纳米晶自组装形成的梭形结构,水热温度和乙酸加入量对TiO_2形貌影响不大,但对TiO_2晶粒大小有影响。以甲基橙溶液为模拟污染物研究TiO_2样品的光催化性能,在紫外光照射下,表现出良好的光催化活性。

Hollow and hierarchical Na_2Li_2Ti_6O_(14) microspheres with high electrochemical performance as anode material for lithium-ion battery

Relying on a solvent thermal method, spherical Na2Li2Ti6O14 was synthesized. All samples prepared by this method are hollow and hierarchical structures with the size of about 2-3 μtm, which are assembled by many primary nanoparticles （-300nm）. Particle morphology analysis shows that with the increase of temperature, the porosity increases and the hollow structure becomes more obvious. Na2Li2Ti6Ol4 obtained at 800℃ exhibits the best electro- chemical performance among all samples. Charge-discharge results show that Na2Li2Ti6O14 prepared at 800℃ can delivers a reversible capacity of 220.1, 181.7, 161.6, 144.2, 118.1 and 97.2 mA h g-1 at 50, 140, 280, 560, 1400, 2800 mA g-1. How- ever, Na2Li2Ti6O4-bulk only delivers a reversible capacity of 187, 125.3, 108.3, 88.7, 69.2 and 54.8 mA h g-1 at the same current densities. The high electrochemical performances of the as-prepared materials can be attributed to the distinctive hollow and hierarchical spheres, which could effectively reduce the diffusion distance of Li ions, increase the con- tact area between electrodes and electrolyte, and buffer the volume changes during Li ion intercalation/deintercalation processes.

Self-assembled multifunctional Fe_(3)O_(4) hierarchical microspheres: high-efficiency lithium-ion battery materials and hydrogenation catalysts

Self-assembled Fe_(3)O_(4)hierarchical microspheres(HMSs) were prepared by a one-pot synchronous reduction–self-assembling (SRSA) hydrothermal method.In this simple and inexpensive synthetic process,only glycerol,water,and a single iron source (potassium ferricyanide (K3[Fe(CN)6]))were employed as reactants without additional reductants,surfactants,or additives.The iron source,K3[Fe(CN)6],and glycerol significantly affected the synthesis of Fe_(3)O_(4)HMSs.Fe_(3)O_(4)HMSs with a self-assembled spherical shape readily functioned as high-performance anode materials for lithiumion batteries with a specific capacity of>1000 mA h g^(-1)at0.5 A g^(-1)after 270 cycles.Further charging and discharging results revealed that Fe_(3)O_(4)HMSs displayed good reversible performance (>1000 mA h g^(-1)) and cycling stability (700 cycles) at 0.5 A g^(-1).Furthermore,as multifunctional materials,the as-obtained Fe_(3)O_(4)HMSs also exhibited high saturation magnetization (99.5 emu g^(-1)) at room temperature (25°C) and could be further employed as efficient and magnetically recyclable catalysts for the hydrogenation of nitro compounds.

Stoichiometry design in hierarchical CoNiFe phosphide for highly efficient water oxidation

Rational composition design of trimetallic phosphide catalysts is of significant importance for enhanced surface reaction and efficient catalytic performance.Herein,hierarchical Co_(x)Ni_(y)Fe_(z)P with precise control of stoichiometric metallic elements(x:y:z=(1-10):(1-10):1)has been synthesized,and Co_(1.3)Ni_(0.5)Fe_(0.2)P,as the most optimal composition,exhibits remarkable catalytic activity(η=320 mV at 10 mA cm^(−2))and long-term stability(ignorable decrease after 10 h continuous test at the current density of 10 mA cm^(−2))toward oxygen evolution reaction(OER).It is found that the surface P in Co_(1.3)Ni_(0.5)Fe_(0.2)P was replaced by O under the OER process.The density function theory calculations before and after long-term stability tests suggest the clear increasing of the density of states near the Fermi level of Co_(1.3)Ni_(0.5)Fe_(0.2)P/Co_(1.3)Ni_(0.5)Fe_(0.2)O,which could enhance the OH−adsorption of our electrocatalysts and the corresponding OER performance.