TiO2(B)基复杂氧化物的制备及其光催化性能改进

Environment pollution has become one of the serious issues caused by modern industry. Photocatalysis is an effective method to solve this problem. Na0.9Mg0.45Ti3.55O8 with TiO2(B) crystal structure exhibits strong photocatalytic effect though TiO2(B) does not. Based on this result, we will prepare TiO2(B)-based complex compounds Na0.35Fe0.75Ti3.35O8 and Na1.97Al1.82Ti6.15O16 by element replacement in the TiO2(B) crystal structure. The complex compounds with uniform morphology and size are our goal by hydrothermal method without post treatments. We will research their photocatalytic characteristics and explore the relationships between the element replacement and physical properties. The properties from different crystal surfaces will be directly measured by a scanning probe microscope equipped with a light source to understand the catalytic mechanism deeply. Then, their band structure and physical properties were adjusted by element replacement in the complex crystal structure. Lastly, the catalytic efficiency will be improved by loading the noble metal nano particles on TiO2(B)-based oxides or compositing with the other semiconductor materials. Through this project, we reveal the effect of material in the catalytic process based on the experimental results with the help of first principle analysis. This work fills the research gaps about TiO2(B)-based complex compounds and seeks the effective photocatalytic materials applied in the pollutant degradation. This research is helpful for solar energy utilization and environmental protection.

现代工业污染严重影响了人们的生活，研发高效的光催化材料是解决这一问题的一个有效途径。TiO2(B)不具有光催化作用，但我们前期研究发现具有TiO2(B)结构的Na0.9Mg0.45Ti3.55O8表现出很强的催化作用，本项目以此为基础，通过置换元素，制备形貌规则、尺寸均匀的另外两种TiO2(B)基复杂氧化物Na0.35Fe0.75Ti3.35O8和Na1.97Al1.82Ti6.15O16，研究他们的结构与性能，并用配置光源的探针扫描显微镜研究晶粒不同表面的性能，直接得到不同晶面催化特征，深入理解化合物的催化机理；然后给这些氧化物中植入多种元素，调节他们的能带特征和物理性能；最后在三种TiO2(B)基氧化物上负载贵金属纳米颗粒，和其他半导体材料复合等，以提高材料的催化效率。本项目以实验为主，结合理论分析，研究晶体表面的作用，研发新催化剂，促进催化材料的应用。

本项目按照研究计划，围绕TiO2(B)基复杂氧化物展开研究，包括Na0.9Mg0.45Ti3.55O8（NMTO）、Na2Fe2Ti6O16（NFTO）、Na0.23TiO2等单相纳米材料，并在此基础上构造异质结，包括TiO2/NMTO、MoS2/NMTO、NMTO/metal、NFTO/g-C3N4、NMTO/SnS2、TiO2/Na0.23TiO2、NFTO/MoS2等，完成了申请书中的既定目标，具体如下：.NMTO、NFTO和Na0.23TiO2具有相同晶体结构和晶格参数。NMTO纳米片具有规则形貌，直接带隙半导体，对MB具有强的催化能力，从实验上和理论上研究了催化机理；NFTO是一种多功能材料，带隙为2.53和2.20 eV的双吸收直接带隙半导体，室温Ms=0.34 emu/g，对MB的最大吸附量165.8 mg/g，可快速脱附，可反复循环使用。.在半导体纳米材料上负载贵金属，构造Schottky结。将Au、Ag和Pt纳米颗粒负载到NMTO表面；在Na0.23TiO2上负载Au或Ag纳米颗粒，明显提高催化性能；用KPFM直接检测到表面电势的降低，金属纳米颗粒中产生局域表面等离子体谐振，热电子转移到半导体，抑制了光生电子空穴对的复合，增强催化性能。.在NMTO和NFTO上基础，制备了n-n异质结TiO2/NMTO和SnS2/NMTO，在晶格层面上匹配良好，降解RhB时显示出增强的光催化性。KPFM探测到异质结在光照下，电子从TiO2和NMTO价带跃迁到导带，迁移到界面，有效分离光生电子空穴对，提高光催化性能，更正了已有报道的载流子迁移的误解。还制备了NFTO/g-C3N4和MoS2/NMTO等异质结，提高了催化效率。.制备了K2Ti8O17纳米线吸附材料，对MB表现出高吸收能力208 mg/g，21min内去除率97%，是目前无机吸附剂中对MB吸附最快的材料，并从理论上进行了解释。