Fabrication and Characterization of Sulphur-doped Graphitic Carbon Nitride Nanosheets as a Highly Selective and Ultrasensitive Electrochemical Sensor for Detection of 2,4-Dinitrophenol in Real Gym Supplements

Herein, an effective template assisted calcination procedure has been adopted to synthesize the Sulphur-doped graphitic carbon nitride (S_XGCN). Furthermore, the S_XGCN/GCE was then utilized for the electrochemical determination of 2,4-Dinitrophenol (2,4-DNP). It has been inferred that among the variously prepared S_XGCN (x=0 %, 20 %, 40 %, 60 %, 80 %, and 100 %), S₈₀GCN afforded the excellent electrochemical response for detection of 2,4-DNP. The synthesized S_XGCN/GCE (x=80 %) demonstrates with a low detection limit of 0.9083 μM with linear range of 1–90 μM. Furthermore, the practical application of this sensor was successfully proved by detecting spiked 2,4-dinitrophenol in a real gym supplements sample.     

Nanosized nickel oxide particles and modification with poly(methyl methacrylate)

In recent years, there is an increasing interest in the fabrication of inorganic–organic materials considering the remarkable change and improvement in properties. In this investigation, nanosized nickel oxide (NiO) particles were first prepared by calcination of nickel hydroxide precursor obtained by a simple liquid‐phase process. Mixed phases of NiO and nickel hydroxide were present as the calcination temperature was lower than 250°C. Non‐stoichiometric NiO was formed between 250°C and 350°C, and a pure NiO was obtained as the temperature reached 500°C. The surface characteristics of NiO particles were evaluated by measuring the adsorption behavior of anionic and cationic surfactants and some biomolecules. NiO/poly(methyl methacrylate) composite particles were then prepared using variable NiO/methyl methacrylate (MMA) ratio by seeded emulsion polymerization. The efficiency of NiO incorporation in the composite increased as the MMA content was increased in the recipe. The composite particles were colloidally stable, and the obtained particles were characterized by Fourier transform infrared, scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectra. Copyright © 2011 John Wiley & Sons, Ltd.     

稀土改性对SO42-/ZrO2固体酸催化剂结构与催化性能的影响

采用共沉淀法和浸渍法在不同条件下制备了稀土-SO₄^2-/ZrO₂系列固体酸催化剂。使用废油脂与甲醇的酯交换反应评价了催化剂活性,并通过X射线衍射、红外光谱、比表面积测定表征方法考察了催化剂结构和性能的关系。结果表明,La摩尔掺杂量4%、焙烧温度600℃时制得的SO₄^2-/ZrO₂-La₂O₃催化剂活性最高,此时脂肪酸甲酯的产率为64.68%,且具有较好的重复使用性。稀土的引入使活性四方相ZrO₂更加稳定,600℃焙烧使催化剂既具有较多活性四方相ZrO₂,又具有较大比表面积,从而提高了催化剂活性。催化剂中形成了固体超强酸结构,且改性后酸强度增大,催化剂活性中心数目增加。     

LED照射光催化剂用于苯、甲苯、乙苯和二甲苯分解(英文)

Studies on the use of gas phase applications of light emitting diodes(LEDs) in photocatalysis are scarce although their photocatalytic decomposition kinetics of environmental pollutants are likely different from those in aqueous solutions.The present study evaluated the use of chips of visible light LEDs to irradiate nitrogen doped titania(N-TiO2) prepared by hydrolysis to decompose gaseous benzene,toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene.Photocatalysts calcined at different temperatures were characterized by various analytical instruments.The degradation efficiency of benzene was close to zero for all conditions.For the other compounds,a conventional 8 W daylight lamp/N-TiO2 unit gave a higher photocatalytic degradation efficiency as compared with that of visible-LED/N-TiO2 units.However,the ratios of degradation efficiency to electric power consumption were higher for the photocatalytic units that used two types of visible-LED lamps(blue and white LEDs).The highest degradation efficiency was observed with the use of a calcination temperature of 350 oC.The average degradation efficiencies for toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene were 35%,68%,94%,and 93%,respectively.The use of blue-and white-LEDs,high light intensity,and low initial concentrations gave high photocatalytic activities for the photocatalytic units using visible-LEDs.The morphological and optical properties of the photocatalysts were correlated to explain the dependence of photocatalytic activity on calcination temperature.The results suggest that visible-LEDs are energy efficient light source for photocatalytic gas phase applications,but the activity depends on the operational conditions.     

焙烧温度对 MnO2-CeO2/Zr0.25Ti0. 25Al0. 5O1.75 整体式催化剂 NH3 低温选择性催化还原 NO 性能的影响

 采用等体积浸渍法在不同温度下焙烧制备了一系列 MnO2-CeO2/Zr0.25Ti0.25Al0.5O1.75 整体式催化剂样品, 并用低温 N2 吸附-脱附、储氧量、X 射线衍射、X 射线光电子能谱和 NH3 程序升温脱附等对催化剂进行了表征, 考察了催化剂上 NH3 选择性催化还原 (SCR) NO 的活性. 结果表明, 随着焙烧温度的升高, 催化剂的比表面积和孔体积逐渐减小, 平均孔径逐渐增大, 储氧能力逐渐降低. 在 500~700 oC 焙烧时, 催化剂主要以无定形或微晶的形式存在; 在 500 oC 焙烧时, 催化剂表面 Mn 与载体之间的相互作用较强, 表面酸量最高, 有利于提高 SCR 活性. 尽管在 600 和 700 oC 焙烧的催化剂仍具有较高的 SCR 活性, 且表现出一定的抗 H2O 和 SO2 性能, 但活性有所下降. 800 oC 焙烧后催化剂的活性显著降低.     

制备方法对 LaMn0.8Mg0.2O3 钙钛矿型氧化物催化甲烷燃烧反应性能的影响

 分别采用甘氨酸硝酸盐法、溶胶凝胶法、共沉淀法、燃烧法以及水热法制备了钙钛矿型 LaMn0.8Mg0.2O3 复合氧化物, 用 X 射线衍射、红外光谱、H2 程序升温还原和低温 N2 吸附对其进行了表征, 并考察了其对甲烷燃烧的催化活性. 结果表明, 制备方法和焙烧温度对 LaMn0.8Mg0.2O3 钙钛矿型催化剂的结构、晶粒大小和不同类型的氧物种影响很大. 以甘氨酸硝酸盐法制备的钙钛矿型催化剂经 700 °C 焙烧后表现出最高的催化活性, T50 (甲烷转化率达到 50% 时的温度) 仅为 440 °C. 这归结于它较小的晶粒尺寸 (12.4 nm) 和较大的比表面积 (18.6 m2/g), 以及催化剂表面富集的 Mn4+, 从而使表面氧物种更容易移动和/或更具有反应活性.     

含铜类水滑石催化材料热分解过程的研究

共沉淀法合成了Cu0.13Mg0 6Al0.27(OH)2(CO3)0.135·xH2O类水滑石物质 (CuHTlc) ,采用XRD、DTA TG、BET、TEM和27AlMASNMR技术对其热分解过程进行了表征。结果表明 ,在较低焙烧温度时 (低于300℃ ),氢氧根和层间水部分脱除 ,但水滑石仍保持其层状结构 ;500℃时 ,其层状结构被完全破坏 ,出现氧化镁晶相结构 ,随着焙烧温度的进一步升高 ,尖晶石晶相生成。500℃时的焙烧产物具有最大比表面 (193m2·g-1)。当温度高于500℃ ,焙烧产物组成可表示为Cu0.13Mg0.6Al0.27O0.135,CuHTlc的热分解过程可表示为 :Cu0.13Mg0.6Al0.27(OH)2(CO3)0.135·xH2O→Cu0.13Mg0.6Al0.27O0.135 (1 x)H2O 0.135CO2。     

煅烧时间对正极材料LiNi0.80Co0.15Al0.05O2浓度梯度结构及电化学性能的影响

将铝溶液按3种不同的流速连续注入,联合共沉淀结晶控制法合成了具有核壳结构的Ni_0.80Co_0.15Al_0.05(OH)₂前驱体,即内核为均相组成的Ni_0.88Co_0.12(OH)₂,外壳为Ni、Co和Al含量呈连续变化的Ni_0.72Co_0.18Al_0.10(OH)₂。将该前驱体与LiOH·H₂O混合均匀,在700℃的氧气气流下进行煅烧,通过控制煅烧时间使材料中Ni、Co和Al扩散形成含量呈连续梯度变化的且具有类球形形貌的LiNi_0.80Co_0.15Al_0.05O₂正极材料。梯度结构中Ni、Co和Al的分布情况直接影响材料的电化学性能和结构稳定性。当煅烧时间为12 h时,从颗粒的核心到表面,Ni含量(原子分数)由0.855下降至0.732,Al含量由0.003增加至0.115,Co含量维持在0.142~0.163之间,而表面组成为LiNi_0.732Co_0.153Al_0.115O₂。此时材料具有良好完整的层状结构且Li⁺/Ni²⁺混排程度最低,在0.2C下的放电比容量为201.3 mAh·g^-1,略低于均相LiNi_0.80Co_0.15Al_0.05O₂的放电比容量(205.8 mAh·g^-1);以0.2C充电、1C放电循环200周后,其容量保留率为71.6%,优于均相组成的材料(54.6%)。这是因为镍含量低而铝、钴含量高(相对于均相材料)的外层可以有效抑制充放电循环过程中引起颗粒体积的各向异性变化,减少电极极化,从而减缓极片表面裂纹的生成和扩展,降低电池的电荷传递阻抗,从而提高循环稳定性和结构稳定性。该材料合成过程中只有在铝溶液流速切换时使pH值发生小幅度的波动,但很快恢复到稳定,可以保证前驱体具有良好的结晶性,使核壳结构易设计、控制;而后通过调控煅烧时间合成LiNi_0.80Co_0.15Al_0.05O₂,有利于进一步地精准设计材料的浓度梯度结构。