奥硝唑在TiO_2(101)晶面上吸附特征的理论研究

奥硝唑残留是一种新兴污染物,对环境和人类健康具有巨大的威胁.采用密度泛函理论,研究了奥硝唑在锐钛矿TiO_2(101)晶面的吸附特性.优化了奥硝唑在锐钛矿TiO_2(101)晶面的吸附结构,计算了最佳吸附位点,吸附能,态密度,电子结构图.结果表明,当咪唑环上N(3)原子吸附在TiO_2的Ti(5)原子上时,吸附能最大,为最稳定的吸附构型.通过对吸附构型的分析,我们发现C(2)-N(3)键呈现变弱趋势,我们推测奥硝唑在TiO_2表面降解的可能性以及反应活性位点就是咪唑环上C-N键.     

聚乙烯醇改性磷酸银的光催化活性研究

在制备的磷酸银表面吸附少量的聚乙烯醇(PVA),并通过热处理制备了DPVA/Ag3 PO4复合材料.使用傅立叶红外光谱法(FT-IR)和荧光光谱法(PL)对DPVA/Ag3 PO4复合材料进行表征.分析得知,经聚乙烯醇复合改性的DPVA/Ag3 PO4复合微粒中存在共轭结构,光生电子-空穴对复合率降低,光催化活性得到显著提高.研究了不同条件(复合比例、热处理温度、热处理时间)下制备的复合光催化剂在可见光下催化降解甲基橙的光催化性能.当PVA与Ag3 PO4质量比为1:4000,热处理温度为190℃,热处理1 h时光催化效果最好.     

二氧化硫水溶液在修饰硫化镉粉末上的光催化反应

本文从应用意图出发,采用CdS、混Pt/CdS和镀Pt/CdS三种光催化剂,研究(1)反应温度,(2)催化剂表面含Pt量,(3)修饰方法和催化剂表面结构形貌对光催化SO₂水溶液生成H₂SO₄同时放H₂反应的活性和选择性的影响。结果表明:(1)本反应有明显温度效应,利用太阳能中约占50％的红外段辐射来提高反应温度到70℃可使活性增至7倍,但选择性下降,(2)估算了反应活化能为21kJ·mol^-1,(3)得出60℃为反应较佳温度,(4)表面含Pt量在5％左右活性最高,(5)混Pt/CdS体系形成高分散、细颗粒分布,其催化活性比镀Pt/CdS体系为高。根据实验结果对反应机理进行了一些讨论。     

介孔InVO4光催化剂的合成及其光催化分解水的性能

 The mesoporous photocatalyst InVO4 was synthesized by the template-directing self-assembling method. The synthesized InVO4 was characterized by means of X-ray diffraction, transmission electron microscopy, N2 adsorption, and ultraviolet-visible spectroscopy. The results showed that the crystal structure of InVO4 could be controlled by changing the calcination temperature. Compared with the anatase TiO2 and conventional InVO4, the mesoporous InVO4 was more responsive toward visible light. The evolution rate of H2 from water over the mesoporous InVO4 achieved 1836 μmol/(g·h) under UV light irradiation, which was much higher than the anatase TiO2 and conventional InVO4.     

Design Principles of Large Cation Incorporation in Halide Perovskites

Perovskites have stood out as excellent photoactive materials with high efficiencies and stabilities, achieved via cation mixing techniques. Overcoming challenges to the stabilization of Perovskite solar cells calls for the development of design principles of large cation incorporation in halide perovskite to accelerate the discovery of optimal stable compositions. Large fluorinated organic cations incorporation is an attractive method for enhancing the intrinsic stability of halide perovskites due to their high dipole moment and moisture-resistant nature. However, a fluorinated cation has a larger ionic size than its non-fluorinated counterpart, falling within the upper boundary of the mixed-cation incorporation. Here, we report on the intrinsic stability of mixed Methylammonium (MA) lead halides at different concentrations of large cation incorporation, namely, ehtylammonium (EA; [CH₃CH₂NH₃]⁺) and 2-fluoroethylammonium (FEA; [CH₂FCH₂NH₃]⁺). Density functional theory (DFT) calculations of the enthalpy of the mixing and analysis of the perovskite structural features enable us to narrow down the compositional search domain for EA and FEA cations around concentrations that preserve the perovskite structure while pointing towards the maximal stability. This work paves the way to developing design principles of a large cation mixture guided by data analysis of DFT data. Finally, we present the automated search of the minimum enthalpy of mixing by implementing Bayesian optimization over the compositional search domain. We introduce and validate an automated workflow designed to accelerate the compositional search, enabling researchers to cut down the computational expense and bias to search for optimal compositions.     

Na2Ta2O6光催化剂的合成、表征及光催化性能分析

通过结合固相反应与水热法制得一种新型的光催化剂Na2Ta2O6,并对其进行了XRD、SEM表征。由紫外可见漫反射光谱推测其禁带宽度约为4.6 eV,并对其在紫外光区下光催化降解碱性藏花红溶液的行为进行了研究。发现其具有好的结晶性、特殊的棒状结构以及较好的光催化活性。     

Fe/Ti/Si复合微粒的表面结构与催化活性

利用UV-vis,FT-IR,XRD,XPS,Raman等手段研究了Ti/Si,Fe/Ti,Fe/Ti/Si复合微粒的表面结构与催化活性。研究表明:Ti/Si复合微粒的光催化活性明显高于TiO~2微粒,TiO~2微粒以晶化度较低的锐钛矿相高度分散在SiO~2网络中,粒径约为10nm;并与SiO~2形成Si-O-Ti桥氧结构;提高了TiO~2微晶的热稳定性、比表面积和表面缺陷;有利于吸附降解有机污染物、半导体光生电子-空穴的分离及提高催化剂的光催化活性。Fe/Ti复合微粒具有Ti-O-Fe网络结构,粒径约为12nm,样品呈晶化度较低的锐钛矿和金红石混晶形式,这种结构有利于促进半导体光生电子-空穴的分离与活性.OH基团的生成;并能在半导体TiO~2中形成杂质中间能级,扩大光响应范围及提高半导体的光催化活性。但是,杂质Fe^3^+的掺入促进了TiO~2微粒的晶格畸变,晶粒增大。所研究的复合微粒中,Fe/Ti/Si体系具有最高的光催化活性。这种体系兼有Ti/Si,Fe/Ti复合微粒的优点,包含Si-O-Si,Si-O-Ti,Ti-O-Ti,Ti-O-Fe多种网络结构的Fe~2O~3,Fe~3O~4,FeO多种物种,具有很高的比表面积和表面缺陷;大大提高了半导体的光催化活性。是一种极具有实用价值的新型光催化剂。     

载钯TiO2半导体悬浮催化体系中CO2的光还原

在半导体光催化还原CO₂的反应过程中,一般都伴有氢气的产生^[1,2].为了提高CO₂还原产物的收率,必须设法抑制析氢过程。在催化剂表面担载某种吸氢物质是抑制氢气产生的有效方法之一。理想的吸氢物质不仅能吸附氢,且被其吸附的氢还具有还原CO₂的能力。     

Bioactivity and Mechanical Properties of Polydimethylsiloxane (PDMS)-CaO-SiO2 Hybrids with Different PDMS Contents

Silica-titania and titania aerogels were prepared by supercritical drying using different solvents such as low temperature CO₂ (353 K), high temperature CO₂ (553 K), ethanol (553 K) and ethanol with zeolite (553 K) and their efficiencies for the removal of benzene from a synthetic air mixture were investigated. The aerogels obtained showed both large capacities for benzene adsorption and high photocatalytic activity for its decomposition in the adsorbed state. The degree of benzene removal by silica-titania aerogel seemed to depend on the crystallinity of the titania and was in the order low temperature CO₂ < high temperature CO₂ < ethanol = ethanol with zeolite. The amount of CO₂ liberated by the photocatalytic decomposition of benzene also followed the same sequence. Titania aerogels showed the greatest efficiency in the decomposition of benzene, while the amount of CO₂ evolved was lower than those of the silica-titania systems investigated. The adsorption capacity of benzene basically depended on the silica matrix and was not greatly influenced by the difference in the crystallinity of titania.     

TiO_2薄膜光催化氧化I~-的研究

采用溶胶－凝胶法,在玻璃珠表面涂覆均匀透明的ＴｉＯ２ 薄膜,并制成光催化反应器对水溶液中Ｉ－的光催化氧化进行了研究。比较了光催化剂的活性,讨论了Ｉ－的起始浓度、试液的酸度、光照时间与Ｉ２产率的关系。实验结果表明：采用锐钛型ＴｉＯ２作光催化剂,３Ｌ碘化钾溶液所用催化剂量为４．０ｇ,［Ｉ－］＝０．３ｍｏｌ·Ｌ－１,［Ｈ＋］＝３．０ｍｏｌ·Ｌ－１,光照８ｈ时,Ｉ２的产率达到４１．２６％。