水分子在均三嗪基g-C3N4上的吸附

气体分子与光催化剂之间的相互作用对于光催化反应的触发非常重要.对于TiO2,ZnO和WO3等传统金属氧化物光催化剂上的水分解反应而言,已有许多报道研究了水分子在它们表面的吸附行为.结果表明,水分子与催化剂表面的原子形成了O-H…O氢键.石墨相氮化碳(g-C3N4)是一种具有可见光响应且化学性质稳定的光催化剂,对其进行修饰以增强其分解水产氢性能的研究非常多.本文通过密度泛函理论计算,全面研究了水分子在均三嗪(s-triazine)基g-C3N4上的吸附情况.首先构建了一系列初始吸附模型,考察了各种吸附位和水分子的朝向.通过比较分析计算得到的吸附能,确定了一种最优的吸附构型,即水分子以竖直的朝向吸附于褶皱的单层g-C3N4表面.水分子中的一个极性O-H键与g-C3N4中一个二配位富电子的氮原子结合形成了分子间的O-H…N氢键.其中,H原子与N原子的间距为1.92?,O-H键的键长由0.976?增至0.994?.进一步通过计算Mulliken电荷,态密度和静电势曲线分析了该吸附体系的电子性质.结果发现在分子间氢键的桥接作用下,g-C3N4上的电子转移至水分子,由此导致g-C3N4的费米能级降低,功函数由4.21 eV增至5.30 eV.在该吸附模型的基础上,考查了不同的吸附距离.当水分子与g-C3N4的间距设为1至4?时,几何优化后总是能得到相同的吸附构型,吸附能和氢键长度也十分相近.随后,通过改变吸附基底g-C3N4的大小和形状,验证了这种吸附构型具有很强的重复性.将2′2单层g-C3N4吸附基底替换为2′2多层g-C3N4(2至5层),3′3和4′4单层g-C3N4,以及具有不同管径的单壁g-C3N4纳米管后,水分子的吸附能随着体系原子数的增多而增大,但吸附模型的几何结构和电子性质基本不变,包括O-H…N氢键的形成和键长,以及电子转移和增大的功函数.另外还研究了非金属元素(P,O,S,Se,F,Cl和Br)掺杂对吸附能的影响.构建模型时,杂质原子以取代二配位氮原子的方式进行掺杂,水分子放置于杂质原子上方.结果显示,引入杂质原子后水分子的吸附能增大,在理论上从吸附的角度解释了元素掺杂增强g-C3N4分解水活性.总之,本文揭示了一种在分子间氢键的作用下,具有高取向性的水分子吸附的g-C3N4构型,这有助于g-C3N4基光催化剂上水分解过程的理解和优化设计.     

基于OBE的人才培养目标制定机制及程序

按照OBE教育理念培养工程技术人才对人才培养目标的修改和完善提出了新的挑战。本文构建了包括行业专家、企业及毕业生代表参与的双循环培养目标论证机制,提出了综合考虑外部及内部需求的培养目标制定程序。     

K_8P_2V_2W_(16)O_(62)/TiO_2复合催化剂的制备及光催化降解罗丹明B

采用溶胶-凝胶-程序升温一步法合成了复合材料K_8P_2V_2W_(16)O_(62)/TiO_2,经X-射线衍射(XRD)、扫描电子显微镜(SEM)对复合材料的结构和形貌进行了表征。结果表明,复合材料K_8P_2V_2W_(16)O_(62)/TiO_2中呈锐钛矿晶型结构的TiO_2附着在多酸K_8P_2V_2W_(16)O_(62)表面。以罗丹明B为模型分子,分别考察了K_8P_2V_2W_(16)O_(62)、TiO_2及复合材料K_8P_2V_2W_(16)O_(62)/TiO_2在紫外光下的降解性能,发现在120 min内,K_8P_2V_2W_(16)O_(62)/TiO_2的光催化活性优于K_8P_2V_2W_(16)O_(62)和TiO_2。     

大学物理实验课程思政和创新教育探索——以光敏传感器实验为例

大学物理实验课程是所有理工类专业学生进入大学后接触的第一门实验课程,在高校人才培养体系中具有十分重要的地位.光敏传感器在现代工业领域具有广泛的应用,其原理包含丰富的物理内涵和思想,是实施课程思政和创新教育的良好载体.详细阐述了光敏传感器实验中所蕴含的思政元素,并介绍了如何利用光敏传感器进行创新实验探索,以达成全方位培养学生科学素养和创新精神的目标.     

钒酸铋/磷钨酸复合催化剂的合成及光催化性能研究

通过水热法合成钒酸铋,通过浸渍法将磷钨酸和钒酸铋进行复合,通过改变钒酸铋在磷钨酸里的掺杂比例得到不同复合比例的钒酸铋/磷钨酸复合材料。通过扫描电子显微镜(SEM)和X-射线粉末衍射(PXRD)等现代分析表征技术对其结构进行表征。以亚甲基蓝溶液模拟染料废液,考察复合催化剂对染料光催化降解率的影响。研究结果表明,在可见光催化条件下,当钒酸铋与磷钨酸的复合比例为0.20∶1时,复合材料对亚甲基蓝的光催化能力最好。     

Influence of Pore-expansion Agent on the Structure and Performance of Activated Alumina Synthesized from Waste Aluminum Sludge

1 INTRODUCTION The reactivity of activated alumina adsorbent is closely related to its specific surface area: the larger the specific surface area, the better its activity and adsorbent capability are. However, in reality, the prac- tically available specific surface area or effective spe- cific area has relationship with its pore structure[1]. Since many reactant molecules are difficult to enter the pores to react with whose radius is shorter than certain critical value, the increase of p…     

Structure and Property Characterization of Oyster Shell Cementing Material

Oyster shell powder was used as the admixture of ordinary portland cement.The effects of different addition amounts and grinding ways on the strength and stability of cement mortar were discussed and proper addition amount of oyster shell powder was determined.The structure and property changes of cementing samples with different oyster shell powder contents were tested by XRD and SEM means.The results revealed that compressive and rupture strengths of the sample with 10% oyster shell powder was close to those of the original one without addition.Stability experiment showed that the sample prepared by pat method had smooth surface without crack and significant expansion or shrinkage after pre-curing and boiling,which indicated that cementing material dosed with oyster shell powder had fine stability.XRD and SEM observation showed that oyster shell independently exists in the cementing material.     

带式输送机动态分析连续模型振动解法及计算机仿真

以头部驱动尾部张紧（考虑张紧装置的惯性力）的带式输送机为例,建立了基于连续单元的动态分析数学模型,求出这一非齐次混合边界条件问题振动解,并进行计算机仿真．     

原料杂质对堇青石窑具晶相结构与性能的影响

对重青石窑具原料中的CaO，TiO2，Fe2O3以及R2O（Na2O＋K2O）对窑具多晶结构与性能的影响进行研究，从而确定原料中的Cao，TiO2，Fe2O3和R2O允许的存在量为CaO（2．2～2．7）％，TiO2（1．0～1．5）％，Fe2O3（0．8）％和R2O≤0．9％。     

Study on the In-situ Synthesis of Aluminum Titanate Sintered by Waste Aluminum Slag

Aluminum titanate was in-situ synthesized by using industrial waste-residue in the aluminum factory and TiO2 as the main raw materials and the influence of different reaction temperatures on the purity and microstructures of synthesized products were mainly discussed. The obtained Al2TiO5 was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and relevant analytical software. The results show that elevating the sintering temperature can increase the content of aluminum titanate; and at 1420 ℃, it reaches the highest in the synthesized ceramic. When the sintering temperature continues to increase, the produced aluminum titanate will decompose resulting in the drop of its content. Therefore, the optimum sintering temperature of in-situ synthesis of aluminum titanate is determined as 1420 ℃, at which the grains of aluminum titanate grow completely, the purity of aluminum titanate is 89.3wt%., the highest density is 2.75 g/cm^3, and the porosity is 9%.