WO3-ZrO2/SBA-15的制备及其可见光催化分析

通过溶胶凝胶法,分别制备了不同负载量的WO_3/SBA-15和WO_3-ZrO_2/SBA-15介孔材料,利用XRD、BET和TEM等表征手段对其进行表征,并对其光降解染料罗丹明B的活性进行比对研究分析。结果表明:Wx/SBA-15(x=20,30,40,50)和W_(40)Zry/SBA-15(y=3,5,7,9)均能在可见光下光降解罗丹明B,光催化活性W_(40)/SBA-15W_(50)/SBA-15W_(30)/SBA-15W_(20)/SBA-15;引入ZrO_2后,光催化活性W_(40)Zr_5/SBA-15W_(40)Zr_9/SBA-15W_(40)Zr_7/SBA-15W_(40)Zr_3/SBA-15。其中,W_(40)/SBA-15和W_(40)Zr_5/SBA-15的光降解效率最高,分别为73.4%和86.6%,ZrO_2的引入提高了光降解效率;同时,WO_3/SBA-15和WO_3-ZrO_2/SBA-15也具有很好的循环价值,可多次使用。     

Ordered SBA-15 mesoporous silica with high amino-functionalization for adsorption of heavy metal ions

Surface NH2 -functionalized SBA-15 mesoporous silica was synthesized using toluene diisocyanate (TDI) as a bridge molecule. First, the surface Si-OH groups of SBA-15 were reacted with the -NCO groups of TDI. Then, the remaining unreacted -NCO groups of TDI were reacted with the -NH2 groups of ethylenediamine (EDA). Finally, the NH2 -groups were successfully grafted onto the mesoporous SBA-15 surface by the above two-step method. XRD, N2 adsorption-desorption analysis, FT-IR, and 29 Si MAS NMR were used to identify the well-ordered structure and the successful incorporation of the -NH2 groups onto the surface of the synthesized materials. Characterizations revealed that such -NH2 grafting is an effective method to obtain a high loading of -NH2 groups onto the SBA-15. When subjected to toxic heavy metal ions in aqueous solution, the obtained NH 2 -functionalized SBA-15 showed very high adsorption rates 99.9%, 99.7%, 99.8%, 99.5% and 99.9% for Pb2+ , Cr3+ , Cd2+ , Ag+ and the Cu2+ , respectively, which is attributed to the strong complexation reactions between the metal ions and the grafted -NH2 groups.     

不同形貌LaBO_3型钙钛矿的制备及其催化H_2O_2分解反应性能

采用柠檬酸络合法制备了La BO3(B=Fe,Co,Ni)钙钛矿催化剂,通过X-射线粉末衍射(XRD)、傅立叶-红外光谱(FT-IR)、透射电镜(TEM)、X-射线光电子能谱(XPS)等对催化剂进行了表征,在室温下测定了其对H2O2的催化分解能力.结果表明:催化分解能力依次为La Ni O3>La Co O3>La Fe O3,说明Ni较Co和Fe能更好地分解H2O2.通过改变La Fe O3催化剂的形貌也能提高催化剂性能,如多孔状La Fe O3较负载在SBA-15上的La Fe O3具有更好的催化分解活性.     

铜锰基SBA-15催化剂的制备及其甲苯燃烧消除的催化性能

以介孔分子筛SBA-15为载体,采用浸渍法分别制备了Cu、Mn和CuMn（物质的量比为1∶1）的质量分数为5%～17%的Cu/SBA-15、Mn/SBA-15和CuMn/SBA-15催化剂,以及Ce质量分数为2.5%～7%、CuMn（物质的量比为1∶1）质量分数为12%的Ce/CuMn/SBA-15催化剂,在常压固定床反应器上评价了这些催化剂对甲苯催化燃烧的反应性能,用X-射线衍射、透射电镜、程度升温还原等分析手段对催化剂的结构进行了研究。活性评价结果表明,Cu质量分数大于12%时,Cu/SBA-15催化剂具有好的活性;Mn质量分数大于8%时,Mn/SBA-15催化剂具有好的活性;CuMn质量分数大于8%时,CuMn/SBA-15催化剂具有好的活性。并且相同Cu、Mn质量分数的双组分催化剂比单组分催化剂的活性要好,在Ce/CuMn/SBA-15催化剂中,Ce质量分数为2.5%～3.5%时,能提高催化剂的活性。结构研究表明,所有催化剂的SBA-15介孔结构仍然保持,并且Cu、Mn等活性组分都已分散在SBA-15分子筛的孔道中。在Ce/CuMn/SBA-15催化剂中,Ce质量分数小于5%时能促进CuMn的分散,并且提高了催化剂的氧化还原能力。     

Nd1-xZnxFeO3纳米材料的甲烷气体气敏性研究

采用Sol-gel法制备出Nd_1-xZn_xFeO₃（x=0, 0.04, 0.08, 0.2）粉体. XRD图谱表明Nd_1-xZn_xFeO₃粉体为正交钙钛矿结构，产物为纳米级颗粒(16～17.5nm)，平均粒径随x的增大有所减小. 用Nd_1-xZn_xFeO₃纳米粉体制成气敏元件，测试了材料对甲烷气体的气敏特性. 测试结果表明Zn的适量掺入可提高对甲烷的灵敏度. 其中以Nd_0.92Zn_0.08FeO₃对甲烷的灵敏度最大，在最佳工作温度200℃下对4×10^-6mol/L的甲烷气体灵敏度最大值为3.87，对2×10^-5mol/L的甲烷气体中灵敏度最大值为16. Nd_0.92Zn_0.08FeO₃还表现出了极好的响应恢复时间特性，工作温度200℃时对2×10^-5mol/L的甲烷响应、恢复时间分别为25s和45s.     

新型介孔钒氧化物催化剂上丙烷高选择性氧化脱氢制丙烯研究

采用醇溶液浸渍法制备了介孔SBA-15、介孔MCM-41及无定形SiO2三种不同氧化硅载体担载的系列钒氧化物催化剂．活性测试结果表明,SBA-15为载体的钒氧化物催化剂具有优良的丙烷氧化脱氢反应性能．BET、SEM/TEM、UV-Vis DRS,TPR,UV Raman和程序升温吡啶-FTIR结果表明：介孔SBA-15载体较大的比表面积及孔径、对钒氧物种较高的分散能力以及催化剂表面仅存在少量的弱酸性位等特点有利于丙烷的活化及产物丙烯的脱附,使得催化剂在丙烷氧化脱氢反应中显示出高活性和高选择性．     

Effect of B sites on the catalytic activities for perovskite oxides La_(.6)Sr_(.4)Co_xFe_(1-x)O_(3-δ) as metal-air batteries catalysts

The effect of B sites on the catalytic activities of oxygen evolution reaction(OER)for perovskite oxides La_(0.6)Sr_(0.4)Co_xFe_(1-x)O_(3-δ)(x=0,0.2,0.4,0.6,0.8,1,denoted as LSF,LSCF-28,LSCF-46,LSCF-64,LSCF-82 and LSC,respectively)prepared by a convenient and simple method of electrospinning technique is reported.The prepared La_(0.6)Sr_(0.4)Co_xFe_(1-x)O_(3-δ)catalysts possess almost same crystal structures,similar morphologies(except for the LSC catalyst)and slightly different BET surface areas.Upon the optimization of the Co/Fe atomic ratio,the optimal LSCF-82 catalyst exhibits the OER performance with a low onset potential of 1.541 V,a small Tafel slope of 80.56 mV dec~(-1),a high charge-transfer rate and a large electrochemical surface area in 0.1 M KOH solution.LSCF-82 catalyst exhibits the long-term stability under the catalytic operation condition for 12 h.Such catalytic activity may mainly cause by the synergy of higher catalytic activity Co and lower catalytic activity Fe.Thus,the reasonable optimization of the transition metal composition in B sites for the perovskite oxides is in favor of the improvement of OER performance.     

FERE法研究M_xO_y(M=Sc、Ti、V、Cr、Mn、Fe、Co、Ni)形成能

采用密度泛函理论(DFT)中的广义梯度近似法(GGA+U)对氧化物M_xO_y(M=Sc、Ti、V、Cr、Mn、Fe、Co、Ni)进行几何结构优化,然后计算其总能,根据形成能与总能的关系求出它们的形成能,再用FERE(Fitted Elemental-phase Reference Energies)方法对形成能进行修正。结果表明:修正后,每个单胞形成能相对实验值的平均绝对偏差由0.59 eV降低到0.46 eV,其中Ti-O、V-O、Co-O和Ni-O化合物的形成能修正值更接近实验值;而其他元素氧化物的形成能修正值相对于实验值的平均绝对偏差略有增大。     

Effects of Cr and Mo elements on the microstructures and compressive properties of the in situ (TiC_xN_y–TiB_2)/Ni cermets

In-situ(TiC_xN_y–TiB_2)/Ni cermets with 70 wt%TiC_xN_y–TiB_2 were successfully fabricated by combustion synthesis and hot pressing sintering in Ni-Ti-B_4C-BN powder systems.The microstructures,density,compressive properties,and hardness of the TiC_xN_y–TiB_2/Ni cermets with the addition of 0–8 wt%Cr/Mo to the Ni-Ti-B_4C-BN powder systems were compared and analysed.The results showed that the ceramic particles distributed uniformly in the cermets,and the size of the ceramic particles reduced with the Cr/Mo addition.Both Cr and Mo addition can improve the hardness,compressive properties,and fracture strains of the cermets.The hardness,compressive strength,and fracture strain of the(TiC_xN_y–TiB_2)/(Ni+Cr)cermets increased from 1561 HV,2.94 GPa,and 2.9%to 1864 HV,3.65 GPa,and 3.4%,respectively when the Cr content increased to 5 wt%.The hardness and compressive strength of the(TiC_xN_y–TiB_2)/(Ni+Mo)cermets increased from 1561 HV and 2.94 GPa to 1902 HV and 3.43 GPa,respectively when the Mo content increased to 8 wt%.The cermets with Cr had better compressive properties than the cermets with Mo.     

Spin-orbit coupling and zero-field splitting of the high-spin ferric enzyme-substrate complex: Protocatechuate 3,4-dioxygenase complexed with 3,4-dihydroxyphenylacetate

We used density functional calculations to investigate the electronic origins of the magnetic properties of the high-spin ferric enzyme-substrate complex protocatechuate 3,4-dioxygenase(3,4-PCD).The calculated g-tensors show that ligand-to-metal charge transfer transitions are from the protocatechuate(PCA) and Tyr408 orbitals to the Fe d orbitals,which lead to x-and y-polarized transitions.These polarized transitions require a spin-orbit coupling(SOC) matrix element in the z-direction,Lz(z=z’),resulting in a g z value of 2.0158,significantly deviating from 2.0023.A large zero-field splitting parameter value of+1.147cm-1 is due to △S =-1 spin-orbit mixing with the quartet states for the sextet ground state,accounting for around 73% of the SOC contribution.The SOC matrix elements indicate that the high-spin d 5 system Fe(Ⅲ),3,4-PCD-PCA is a weak spin-crossover compound with an SOC of 31.56 cm-1.     

Ice core dust particulate by XPS-SEM/EDAX

The ice core dust particulate sampled from Mt. Xixabangma has been analyzed by means of X-ray photoelectron spectrometer (XPS) and scanning electron microscope with energy dispersion X-ray analysis (SEM/EDAX). The results show that the contents of SO ₄ ²⁻ and SO ₄ ²⁻ in the surface layer of the dust are significantly higher than those in the subsurface layer (with the exception of organic sulfide). This difference indicates that the surface SO_x has been captured and then chemically converted by the atmospheric dust particulate before its deposition with snow, which is obviously different from those inner layer sulfates and sulfites contained by dust itself. In addition, it has been determined by SEM/EDAX that the dust contains relatively high concentrations of transition metal elements such as Fe and Ti oxides which could function as photocatalysts to the conversion of SO_x adhered on the surface of the dust, and consequently accelerate the deposition of SO_x to snow. Our research also demonstrates that the adsorptive carrying and the catalytic performance of the dust to the atmospheric SO_x are most important causes of the positive correlation between SO ₄ ²⁻ and dust concentration records in ice cores.     

Selective catalytic reduction of NO x by hydrogen over modified Pd/TiO2-Al2O3 catalyst under lean-burn conditions

A series of Ni, Sn and Ca modified Pd/TiO2-Al2O3 catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOx by H2 was evaluated. The results showed that the NOx conversion and N2 selectivity were improved over Pd-Sn/TiO2-Al2O3 and Pd-Ni/TiO2- Al2O3 catalysts above 200 ℃. More importantly, the N2 selectivity and high-temperature activity of Pd-Sn/TiO2- Al2O3 catalyst was far superior to the single Pd/TiO2-Al2O3 catalyst. The optimal Sn loading was 2 wt.%. X-ray diffrac- tion （XRD） results showed that the interaction between Pd and Sn promotes the dispersion of Pd over TiO2-Al2O3. Temper- ature-programmed reduction （Ha-TPR） results demonstrated that the addition of Sn contributes to the formation of PdO and improving the redox property of Pd/TiOz-Al2O3. The addi- tives of Ni and Sn also facilitated the absorption of NOx and the oxidation of NO to NOa, which play important roles in the selective catalytic reduction of NOx by hydrogen.     

Mechanism of forming an ink-bottle-like pore structure based on SBA-15 by a novel MOCVD technique

Metallorganic chemical vapor deposition is used as a novel simple pore tailoring method to fine-tune the pore opening size of SBA-15 materials without significant loss in pore volume and surface area. By using acetylene as carbon source and copper (II) acetylacetonate as precursor, the poremouth of SBA-15 is effectively reduced from 5.78 nm to 3.67 nm while maintaining the pore body at 5.78 nm. The effect of four pore modification factors-the ratio of acetylene/nitrogen, the feeding time of carbon precursor, the ratio of SBA-C/Cu(acac)₂ and the cycles of MOCVD on the final pore structure of the SBA-15/carbon/copper composite is studied. The morphology and microstructure of the resulting product SBA-C-Cu are characterized by XRD patterns, TEM images and EDS analysis. The XRD and TEM reveal that the SBA-C-Cu composite is highly hexagonally ordered and has similar particle morphology as the original SBA-15.     

硫酸化的SBA-15负载Cr2O3催化剂上丙烷CO2氧化脱氢

合成了一系列表面经硫酸铵处理的SBA-15负载Cr2O3催化剂,研究了这些催化剂对于丙烷CO2氧化脱氢反应的活性．结果发现,载体表面硫酸化后催化剂的活性大大增加．表征结果表明催化剂活性的提高与硫酸化后催化剂表面含有较多量的Cr^6 有关,而与表面酸性的增强无关．但载体表面硫酸化后由于积碳严重,催化剂的失活也随之加快．     

Glass-forming ability,microhardness, corrosion resistance,and dealloying treatment of Mg60-xCu40Ndx alloy ribbons

The influence of Nd addition on the glass-forming ability (GFA), microhardness, and corrosion resistance of Mg_60-xCu₄₀Nd_x (x=5, 10, 15, 20, and 25, at%) alloys were investigated by differential scanning calorimetry, Vickers-type hardness tests, and electrochemical methods. The results suggest that the GFA and microhardness of the amorphous alloys increase until the Nd content reaches 20at%. The corrosion potential and corrosion current density obtained from the Tafel curves indicate that the Mg₃₅Cu₄₀Nd₂₅ ternary alloy exhibits the best corrosion resistance among the investigated alloys. Notably, nanoporous copper (NPC) was synthesized through a single-step dealloying of Mg_60-xCu₄₀Nd_x (x=5, 10, 15, 20, and 25) ternary alloys in 0.04 mol·L-1 H₂SO₄ solution under free corrosion conditions. The influence of dealloying process parameters, such as dealloying time and temperature, on the microstructure of the ribbons was also studied using the surface diffusivity theory. The formation mechanism of dealloyed samples with a multilayered structure was also discussed.     

二维NiFe-LDH/Mo(OS)x纳米片协同促进电催化析氧反应

过渡族金属基二维纳米材料作为电催化析氧反应（oxygen evolution reaction, OER）催化剂具有巨大的潜力。通过原位电沉积法,在泡沫镍基底表面制备了二维层状镍铁双氢氧化物（NiFe-LDH）和氧硫化钼Mo(OS)_x纳米片异质结构。NiFe LDH/Mo(OS)_x电极在1 M KOH溶液中表现出优异的OER性能和长效稳定性,在10 mA/cm²电流密度下过电势仅为220 mV。在100、500 mA/cm²的高电流密度下,也能达到253、304 mV的低过电势。研究结果表明,NiFe-LDH/Mo(OS)_x电极优异的OER性能归因于Mo(OS)_x和NiFe LDH的协同作用,极大地促进了Fe²⁺向Fe³⁺活性物质的转化,并促进了氧空位的形成。这种协同制备方法为合理构建和设计异质结构电催化剂,实现高效的水分解提供了帮助。     

二维1:-5 Lotka-Volterra复四次系统的可线性化条件

本文考虑了如下的一类平面四次复Lotka-Volterra系统的可线性化问题ẋ=x（1-a₃₀x³-a₂₁x²y-a₁₂xy²-a₀₃y³）,ẏ=-y（5-b₃₀x³-b₂₁x²y-b₁₂xy²-b₀₃y³）.该系统为四次齐次多项式扰动下的具有$1:-5$线性项的复Lotka-Volterra系统,给出了该系统可线性化的充分必要条件.     

Structural,elemental, optical and magnetic study of Fe doped ZnO and impurity phase formation

We have prepared a series of(ZnO)1-x(Fe2O3)x≤0.10bulk samples with various concentrations of Fe dopant by ball milling and investigated their structural, compositional, optical and magnetic properties by means of X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS),Raman spectrometer and vibrating sample magnetometer(VSM), respectively. Information about different impurity phases was obtained through Rietveld refinements of XRD data analysis. XPS results showed different valence states(Fe2+ tand Fe3+) supported by shaking satellite peaks in samples. With increasing Fe doping percentage, the crystal quality deteriorated and a shift of E2 low band(characteristic of ZnO) has been observed in Raman spectra. Energy band gap estimated from reflectance UV–vis spectroscopy showed shift for all bulk samples. The magnetic behavior was examined using a vibrating sample magnetometer(VSM), indicating ferromagnetic behavior at room temperature(300 K). The effective magnetic moment per Fe atom decreases with increase in doping percentage which indicates that ferromagnetic behavior arises from the substitution of Fe ions in the ZnO lattice.     

PbxNayYzF2x+y+3z+3m∶Erm3+上转换发光粉的低温燃烧合成及表征

采用低温燃烧合成（LCS）法一步合成了Pb_xNa_yY_zF_2x+y+3z+3m:Er_m3+氟化物体系1 550 nm响应的红外上转换发光材料. 通过正交实验研究了4种阳离子影响发光性能的主次关系及最佳配比,研究了燃料用量对晶相形成及上转换发光性能的影响. 采用X射线粉末衍射仪、透射电镜、荧光分光光度计（耦合1 550 nm激光器）等手段对样品的物相、形貌及发光性能进行了测试与表征. 结果表明:阳离子含量对红光发射强度影响的主次关系为Y3+,Pb2+,Na+,Er3+,最佳配比为Pb_0.004Na_0.003 Y_0.003 F_0.032:Er3+_0.004. 燃料取2.5倍理论用量时样品的结晶度和发光强度最高.      

Highly dispers ed iron species created on alkali-treated zeolite for ammonia SCR

Alkaline treatment using sodium hydroxide was introduced to obtain a hierarchical pore structure in H-ZSM-5 zeolite.Fe-exchanged zeolite catalysts were prepared by impregnation on the original and alkali-treated zeolites,and were evaluated for NOx reduction by NH3,NO oxidation,and NH3 oxidation reactions.The highly dispersed iron species as active sites can be obtained by controlling the pore structure and particle size of zeolite.Therefore,the Fe/ZSM-5 catalyst treated mildly by sodium hydroxide before iron exchange,which contains amounts of highly dispersed Fe species,obtains over80% NOx conversion at a wide temperature range of 250-500℃.