CuCrO_2-WO_3的制备及光催化产氢性能

作为分解水制氢用光催化剂,p-n半导体物质的复合体具有较好的开发前景。燃烧法合成了p型半导体物质CuCrO2,钨酸分解法合成了n型半导体物质WO3,在此基础上经机械研磨及热处理的方法制备了CuCrO2-WO3和Ru/(CuCrO2-WO3)复合光催化剂。对制得的样品进行了X射线衍射(XRD)、紫外可见漫反射(UV-Vis DR)、扫描电镜(SEM)及X射线光电子能谱(XPS)表征分析。测定了CuCrO2、WO3、CuCrO2-WO3及Ru/(CuCrO2-WO3)在氙灯照射下的产氢活性,考察了研磨介质pH及钌负载量对CuCrO2-WO3光催化活性的影响。实验结果表明,CuCrO2和WO3单独使用时几乎没有活性,而复合催化剂CuCrO2-WO3在以甘油为电子给体的情况下具有产氢活性,研磨介质pH对复合催化剂的活性影响较大;负载钌后CuCrO2-WO3的活性得到进一步的提高,能分解纯水放出氢气,以0.5%Ru/(CuCrO2-WO3)为光催化剂,在300W氙灯照射下,3 h内分解纯水放出氢气约10μmol。     

燃烧法合成CuCrO_2及其与WO_3复合后的光催化产氢性能

以硝酸铜、硝酸铬为原料,以甘氨酸和柠檬酸为复合燃烧剂,采用溶液燃烧法合成CuCrO_2,并将其与WO_3复合,制备复合催化剂CuCrO_2-WO_3,用于光催化分解水制氢的反应。通过X射线衍射、扫描电子显微镜、紫外可见漫反射光谱及BET比表面积对合成的CuCrO_2样品进行了表征,考察了复合燃烧剂比例、燃烧液中氨水加入量和NaCl或KCl加入量对CuCrO_2形貌及对应CuCrO_2-WO_3产氢性能的影响。结果表明:目标合成物CuCrO_2为5 g,甘氨酸与金属离子总量摩尔比为1.4:1的情况下,当柠檬酸和甘氨酸复合比例为0.10:1、1 mol/L NH_3·H_2O加入量为10 mL、NaCl加入量为1.1 g时制得的CuCrO_2样品分散性较好,对应的复合催化剂光催化活性较高。     

燃烧法制备镁铝尖晶石粉体及其烧结活性研究

按Mg(NO3)2.6H2O与A l(NO3)3.9H2O的摩尔比为1∶2配料,分别添加20.120 g尿素、15.015 g尿素+4.500 g甘氨酸、7.987 g尿素+9.980 g甘氨酸为燃烧剂,采用燃烧合成法制备了镁铝尖晶石粉体,分析了镁铝尖晶石粉体的物相组成和显微结构,并用谢乐公式计算粉体的晶粒尺寸;然后,将镁铝尖晶石粉体成型为样块,在1 600℃保温3 h煅烧,计算块体的烧后永久线变化率,并检测烧后块体的吸水率、显气孔率和体积密度,分析其显微结构。结果表明:1)随着燃烧剂中甘氨酸含量的增加,制备的镁铝尖晶石粉体的晶粒尺寸逐渐减小,粒径分布逐渐均匀,但团聚现象逐渐明显。2)随着燃烧剂中甘氨酸含量的增加,由镁铝尖晶石粉体制成的块体在1 600℃保温3 h煅烧后的永久线收缩率逐渐增大,烧后块体的吸水率和显气孔率逐渐减小,体积密度逐渐增大;烧后块体中的颗粒粒径逐渐均匀,异常长大的晶粒逐渐减少。这表明,在燃烧剂中添加甘氨酸有利于提高燃烧合成法制备的镁铝尖晶石粉体的烧结活性。     

非贵金属Ni2P助催化剂修饰KCa2Nb3O10超薄纳米片的光解水产氢性能研究

开发高效非贵金属助催化剂是光解水产氢领域研究的重点.首次将Ni2P纳米颗粒作为高效助催化剂经一步热处理法修饰在KCa2Nb3O10超薄纳米片表面,成功构建了Ni2P/KCa2Nb3O10复合光催化剂,所制备的复合光催化剂展现出具有丰富异质界面的二维纳米结构,活性最佳的Ni2P/KCa2Nb3O10产物光催化产氢效率高达72.25μmol g-1 h-1,是纯相KCa2Nb3O10产氢效率的18.8倍.提供了一种负载其他非贵金属助催化剂制备高效KCa2Nb3O10基复合光催化剂的新策略.     

纳米ZnO/SnO2粉体的制备及其光催化性能的研究

以SnCl4·5H2O、ZnNO3·6H2O、HCl、NaOH为原料,采用共沉淀法制备出纳米ZnO/SnO2纳米复合催化剂粉体,以降解甲基橙溶液反应为模型,考察了不同比例ZnO/SnO2纳米粉体的光催化活性,探讨了煅烧温度对催化剂催化活性的影响.并用差热失重分析仪(TG/DSC)、透射电镜(TEM)、X-射线衍射(XRD)测试手段对其进行了表征.结果表明:ZnO复合SnO2后,光催化活性明显提高,其中以ZnO/SnO2在ZnO∶SnO2=4∶1的情况下复合催化剂光催化性能最优;热处理温度在650℃保温时间2h所得到的复合催化剂催化性能最好.     

抗坏血酸为燃烧剂合成铜锰复合物及光催化研究

采用抗坏血酸为燃烧剂,高锰酸钾和硝酸铜为原料,通过燃烧法快速合成铜锰复合氧化物。利用XRD表征分析考察原料高锰酸钾和硝酸铜摩尔比对复合物结构和性能的影响;利用电镜表征样品的形貌;利用BET考察样品的比表面积。并以此复合物为催化剂和吸附脱色剂考察复合物对亚甲基蓝的光催化性能和对酸性品红的脱色性能。同时,考察了复合物的类型、催化剂的用量、溶液的pH、H_2O_2用量等对催化剂光催化和脱色的影响。     

不同燃烧剂对合成YAG:Ce3+黄色荧光粉的影响研究

本文采用燃烧法,分别选取尿素、甘氨酸和柠檬酸作为燃烧剂,成功合成了YAG:Ce3+黄色荧光粉.采用XRD和PL光谱分析,研究了不同燃烧剂对荧光粉结构及荧光性能的影响.结果表明,所有样品均为纯相的Y3Al5O12,以尿素作为燃烧剂时,合成的荧光粉的结晶性最好,荧光强度最强.YAG:Ce3+荧光粉可被450 nm的蓝光激发...     

Cd Te-QDs/g-C_3N_4的合成及其高效可见光光催化产氢研究

CdTe量子点在可见光下具有优异的光催化制氢活性,将CdTe量子点修饰到石墨相氮化碳(g-C_3N_4)表面可以进一步提高其产氢活性。采用一步水热法合成了CdTe QDs/g-C_3N_4复合光催化剂,并用XRD、TEM、DRS、FT-IR和PL对其进行分析。在以CoCl_2为助催化剂和抗坏血酸(H_2A)为牺牲剂的条件下,得到的复合光催化剂在可见光照射下比纯CdTe QDs和gC_3N_4表现出更高的产氢活性。其中质量分数为20%CdTe QDs/g-C_3N_4的复合材料的H2生成量为4. 8 mmol,是纯CdTe QDs的2. 4倍。     

燃烧快速制备铁酸铋复合氧化物及光催化研究

本文采用新型燃烧剂抗坏血酸,燃烧法快速制备铁酸铋的复合氧化物.经XRD考察硝酸铁和硝酸铋物质量之比对复合氧化物的影响,电镜表征复合氧化物的形貌、BET表征复合氧化物的比表面积、紫外和红外表征复合氧化物的吸光性能.以甲基橙为目标降解物对铁酸铋的复合氧化物进行光催化研究.本文考察了复合氧化物类型、催化剂用量、溶液酸度、双氧水用量、光照时间对光催化效果的影响.最佳光催化条件为催化剂用量为0.01 g/L,pH值为5,双氧水用量为60 mL/L.BiFeO3在紫外和可见光下均有较好的光催化效果,Bi2Fe4O9只在紫外光下有较好的光催化效果.     

助剂对二氧化碳加氢合成甲醇催化剂性能的影响

采用并流共沉淀方法制备了CuO-ZnO-ZrO2催化剂,并以金属氧化物为助剂对其进行了改性,在固定窗连续流动反应装置上考察了Ag2O和La2O32种助剂对CuO-ZnO-ZrO2催化剂催化CO2加氢合成甲醇反应性能的影响,及不同La2O3含量的CuO-ZnO-ZrO2的催化性能,采用X射线衍射(XRD)、H2-程序升温还原(H2-TPR)等方法对催化剂进行了表征。实验结果表明Ag2O和La2O3都可以提高CuO-ZnO-ZrO2催化剂的活性,而且添加6%La2O3(文中均指质量分数)的催化剂催化效果最好。添加Ag2O的催化剂中Ag作为活性中心参与CO2加氢合成甲醇的反应;对于La2O3改性的CuO-ZnO-ZrO2催化剂,适量La2O3有利于提高催化剂中CuO和ZnO的分散度。     

Preparation and characterization of delafossite CuCrO2 film on flexible substrate

Delafossite CuCrO₂ film was successfully prepared on a flexible plastic substrate using a heat transfer process. The metallic acetate of the first layer decomposed to form a carbonized layer for use as a release layer. The thin film was deposited on the first layer by chemical solution deposition and heat treated to form a CuCrO₂ film. After that, the delafossite CuCrO₂ film was transferred from a Si substrate to a polymethyl methacrylate (PMMA) substrate. The CuCrO₂/PMMA film structure, morphology, and optical properties were studied by different characterization techniques. X-ray diffraction analysis and Raman spectrum analysis confirmed that the delafossite CuCrO₂ film was transferred onto the PMMA substrate. XPS analysis showed that the metallic acetate was annealed in N₂ to form a carbonized layer. The resistivity of the CuCrO₂/PMMA was gauged by a four-point probe method, and the visible light transmittance was approximately 58%.     

Delafossite CuCrO2 nanoparticles as possible electrode material for electrochemical supercapacitor

Delafossites are popularly known materials for thermoelectric and electrochemical device applications due to their layered structural features. In this paper, delafossite CuCrO₂ nanoparticles (NPs) have been synthesized using a simple chemical procedure and are investigated as a supercapacitor material. To determine the phases of delafossite CuCrO₂ NPs, the morphological and phase formation experiments were conducted using diffraction patterns and microscopic analysis. The cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) studies were performed to evaluate the supercapacitative behavior of delafossite CuCrO₂ NPs. As prepared delafossite CuCrO₂ NPs based electrode showed an outstanding electrochemical property as compared to annealed delafossite CuCrO₂ NPs at 300–500 °C. A good specific capacitance of ～464.7 Fg^-1 at 0.01 Vs^-1 was found for the fabricated supercapacitor using non-annealed delafossite CuCrO₂ NPs based electrode, which was further validated by GCD results. The electrochemical supercapacitor fabricated with both non-annealed and annealed delafossite CuCrO₂ NPs displayed considerably the outstanding cycling stability by maintaining up to ～88% after 5000 cycles. This work sets the pace for a new and efficient method of preparing delafossite CuCrO₂ for high-performance electrochemical supercapacitors.     

CuCrO2-WO3的制备及光催化产氢性能

作为分解水制氢用光催化剂,p-n半导体物质的复合体具有较好的开发前景。燃烧法合成了p型半导体物质CuCrO₂,钨酸分解法合成了n型半导体物质WO₃,在此基础上经机械研磨及热处理的方法制备了CuCrO₂-WO₃和Ru/（CuCrO₂-WO₃）复合光催化剂。对制得的样品进行了X射线衍射（XRD）、紫外可见漫反射（UV-Vis DR）、扫描电镜（SEM）及X射线光电子能谱（XPS）表征分析。测定了CuCrO₂、WO₃、CuCrO₂-WO₃及Ru/（CuCrO₂-WO₃）在氙灯照射下的产氢活性,考察了研磨介质pH及钌负载量对CuCrO₂-WO₃光催化活性的影响。实验结果表明,CuCrO₂和WO₃单独使用时几乎没有活性,而复合催化剂CuCrO₂-WO₃在以甘油为电子给体的情况下具有产氢活性,研磨介质pH对复合催化剂的活性影响较大;负载钌后CuCrO₂-WO₃的活性得到进一步的提高,能分解纯水放出氢气,以0.5%Ru/（CuCrO₂-WO₃）为光催化剂,在300W氙灯照射下,3 h内分解纯水放出氢气约10 μmol。     

Evaluation of Ni doping for promoting favorable electronic structures in CuCrO2 and AgCrO2 from a first-principles perspective

Doping transparent conducting oxides in the delafossite form with Ni has been presented in the literature as an exciting candidate to improving the conductivity while maintaining the transparency of these materials. Here, the effects of 6.25% Ni doping on the electronic, structural, and hole effective masses in the 2H phase of XCrO₂ (X = Cu, Ag) is studied using spin polarized ab initio calculations. 6.25% Ni doping is found to produce an asymmetry across spin in both materials, as well as decrease the bandgaps, potentially harming transparent character. Hole effective masses are calculated to be heavier in every lattice vector direction for CuCrO₂, but in AgCrO₂ hole effective masses are lighter overall. Considering that 6.25% Ni doping introduces an increase in hole concentration, AgCr_0.94Ni_0.06O₂ should have a higher conductivity as result of 6.25% Ni doping, while the same doping may reduce the conductivity of CrCr_0.94Ni_0.06O₂.     

Conductivity improvement of CuCrO2 nanoparticles by Zn doping and their application in solid-state dye-sensitized solar cells

Undoped and Zn-doped CuCrO₂ nanoparticles were synthesized by sol–gel method as promising wide band gap p-type semiconductor materials for solid-state dye-sensitized solar cells (DSSCs). We studied the influence of Zn dopant concentration on structural, electrical and optical properties of CuCrO₂ nanoparticles. The X-ray diffraction data indicated that the delafossite-to-spinel ferrite phase transition occurs by increasing the amount of Zn doping. The average nanoparticle size was determined about 40 nm. A minimum value of electrical resistivity of 5.7 Ω cm was obtained for doping concentration of 5%. Having optimized the Zn-doped CuCrO₂ nanoparticles, solid-state DSSCs were fabricated using undoped and Zn-doped CuCrO₂ (5%) as solid electrolytes. As the photoanode layer, the vertically aligned TiO₂ nanorod arrays were grown on FTO glass using a hydrothermal method. Compared with undoped CuCrO₂, the Zn-doped nanoparticles exhibited an improvement in photovoltaic properties. The overall efficiency enhancement of 39% was obtained for the dopant concentration of 5%. The improved power conversion efficiency is attributed to the lowered electrical resistivity and enlarged work function of Zn-doped CuCrO₂ nanoparticles.     

Formation and characterization of p-type semiconductor CuCrO2 thin films prepared by a sol–gel method

This study adopted the sol–gel method to synthesize p-type semiconductor CuCrO₂ films and analyzed the effects of an annealing treatment, under a controlled argon atmosphere by changing the temperature and time, on the phase transformation, micro- and nano-structure, composition, and semiconductor properties of thin films. In the Cu–Cr–O phase transformation system, CuO, Cr₂O₃, and CuCr₂O₄ were the intermediate phases of the reaction for forming CuCrO₂: in the metastable state reaction process, the composite phases changed into a single phase, CuCrO₂; in the stable-state reaction process of CuCrO₂, carbon elements of precursors were released and eliminated; and finally the optoelectronic properties of the CuCrO₂ thin film were adjusted and changed. The CuCrO₂ thin film possessed cell- and polygon-like shaped microstructures. The carbon content in the CuCrO₂ film decreased, so the copper, chromium, and oxygen contents increased accordingly. The optical band gap of CuCrO₂ thin film increased from 2.81 eV to 3.05 eV, while the resistivity decreased. The nanoscale crystal was identified which also of the delafossite CuCrO₂ structure. Using the sol–gel method to prepare the CuCrO₂ thin films, an appropriate annealing temperature and time were helpful in forming the single-phase CuCrO₂; the decrease of precursor elements in the thin film could enhance the band gap and the conductivity of the material.     

Low temperature synthesis and effect of Co doping on structural,optical and dielectric properties of CuCrO2 hexagonal nanoplates

In this research work, delafossite oxide CuCrO₂ and its different Co doped compositions CuCr_1-xCo_xO₂ (x = 0.05, 0.1, 0.15) were successfully synthesized by low temperature hydrothermal method. X-ray diffraction (XRD) confirmed the formation of CuCrO₂ nanostructures with hexagonal structure having crystallite size less than 100 nm. The XRD peaks also confirmed that the fraction of Cr ions are perfectly replaced by the Co ions in the lattice structure. The crystallite size was found to decrease with increasing the doping concentration. The formation of nanoplates with hexagonal morphology was studied by using scanning electron microscope (SEM). The Fourier transform infrared spectroscopy (FTIR) was employed to analyze the occurrence of various functional groups, stretching and vibrational modes. Tauc's relation was used to calculate the optical band gap (E_g) of the samples from the absorbance spectra. E_g was observed to increase from 3.61eV to 3.95 eV which may be attributed to the reduction in crystallite size as a result of Co doping. The doping concentration also increases the density of grain boundaries which in turn induced the lattice strain in the crystal structure. The interplanar spacing d was observed to increase from 2.489 Å to 2.508 Å resulted due to induced strain. A maximum strain of 0.0132 was found in CuCr_0.85Co_0.15O₂. The impedance and dielectric dispersion of the material were measured using LCR meter. The Cole-Cole plots represent the perfect dielectric behaviour of these materials indicating the pre dominant grain boundary resistance. The dielectric constant showed the increasing behaviour with Co doping concentration. Our results show that manipulation of the band gap and dielectric properties of CuCrO₂ nanoplates with doping of Co ions can broadly enhance the efficiency and the applications of these oxide materials.     

甲基丙烯酸-2,2,2-三氟乙酯的制备

采用一锅法的工艺通过甲基丙烯酸先酰氯化,再与2,2,2-三氟乙醇在催化剂4-二甲氨基吡啶的催化下酯化的方法,方便快捷地制备了甲基丙烯酸-2,2,2-三氟乙酯,并根据实验结果讨论了影响反应的主要因素。最佳反应条件是:二甲基甲酰胺(DMF)和4-二甲氨基吡啶(DMAP)的用量为5%~10%(质量比),甲基丙烯酸∶氯化亚砜∶2,2,2-三氟乙醇=1.1∶1∶0.9(摩尔比),反应温度为50~60℃,收率达到95%以上。     

生产乙炔对电石的要求及乙炔清净

目前国内外乙炔大部分仍是由电石制得。然而由于工业电石除CaC2 外还含有很多杂质 ,所以生产乙炔不仅要求电石的纯度、粒度 ,还要求水温。一般电石的块度采用 8～ 2 5mm ,发生器温度控制在 85± 5℃ ,乙炔气体中含H2 S、H3 P、NH3 等气体会使氯乙烯合成氯化催化剂活性下降。因此 ,必须对乙炔气体进行清洁。采用次氯酸钠液体的氧化性将乙炔中的杂质氧化成酸性物质而除去。