面向清洁能源领域的新型复合光催化材料的设计合成及其可见光活性调控

The aim of this project is to design and synthesize photocatalytic materials with such properties as wide wavelength light response, high efficiency and stability, and integrate the investigation techniques of photocatalytic materials characterization, calculation of density functional theory (DFT), and electron energy band structure and microstructure design based on the photocatalysts, to explore the controllable mechanism of photocatalytic activity and take full advantage of the visible light in the solar energy. Base on DFT, the crystal structure, the energy band structure of undoped, nitrogen doped, iodine doped, and platinum doped TiO2 are calculated by CASTEP code. The relationship between the crystal structure and the energy band structure of doped TiO2 and the photocatalytic performance are investigated further. The Degussa P25 photocatsaysts are modified by a simple one-step vacuum activation method, and the superhydropobic MCF loaded with TiO2 composite photocatalysts are prepared by a one-step hydrothermal method with a cheap and low toxic inorganic NH4F as hydrophobic modifier. Based on these mentioned above, the crystal, valence, morphology and optical properties of the prepared composite photocatalysts are characterized by XRD, XPS, BET, SEM, TEM and UV-DRS. And their photocatalytic activities of the composite photocatalysts under visible light irradiation are evaluated using methyl orange (MO) or phenol as the pollutant models. The modification mechanisms of Degussa P25 photocatsaysts by the vacuum activation and MCF/TiO2 composite photocatalysts by the hydrothermal method will be explored. Thus a new strategy and method for high efficiency composite photocatalysts design and control of their visible light photocatalytic activity could be established.

本项目拟设计合成具有宽谱响应高效稳定的复合光催化材料，结合催化剂表征手段、密度泛函理论(DFT)计算以及基于催化剂电子能带结构和微观结构设计等方法，探索光催化性能的调控机制，以便充分利用太阳能中的可见光。采用DFT的CASTEP代码计算未掺杂、N掺杂、I掺杂和Pt掺杂TiO2的晶体结构和电子能带结构，探索晶体结构、能带结构与光催化性能的关系；采用简单的一步低温真空活化法对P25光催化剂进行还原改性，一步水热法制备疏水型F掺杂改性TiO2/MCF复合光催化材料。结合XRD、XPS、BET、SEM、TEM和UV-DRS等技术对复合光催化材料的晶相、化合价态、形貌及其光学性能进行表征分析，以甲基橙和苯酚等为模型污染物评价其可见光催化活性，探索P25及TiO2/MCF复合光催化材料真空活化及表面氟化改性机理，为新型高效复合光催化材料的结构设计及可见光活性调控的策略和方法提供理论基础和实验依据。

本项目设计合成了具有宽谱响应高效稳定的复合光催化材料，结合XRD, FT-IR, XPS, BET, SEM, TEM, UV-vis/DRS和PL等先进的催化剂表征手段、密度泛函理论(DFT)计算以及基于催化剂电子能带结构和微观结构设计等方法，探索光催化性能的调控机制，以便充分利用太阳能中的可见光。课题研究成果包括：.以剥离的层状金属硫化物LMS (LMS = MoS2, WS2和SnS2)为敏化剂，TiCl4为钛源，采用液相剥离和溶胶凝胶−乙醇热方法，分别构建了TiO2/MoS2、TiO2/WS2和TiO2/SnS2复合光催化剂。当MoS2，WS2和SnS2与TiO2的摩尔比分别为0.8:50，0.2:50和0.1:50时，所得TiO2/LMS复合催化剂对甲基蓝(MB)、甲基橙(MO)及4-硝基酚表现出较高的光催化活性。通过自由基捕获剂实验，研究了超氧自由基(•O2-)、羟基自由基(•OH)、电子(e-)及空穴(h+)对降解过程的影响。.分别以g-C3N4/MoS2、g-C3N4/WS2和g-C3N4/SnS2杂化复合物为共催化剂改性TiO2，制备了三元复合光催化剂TiO2/g-C3N4/LMS (LMS = MoS2, WS2, SnS2)，对样品的结构、形貌、表面组成及光学特性等进行表征。当MoS2、WS2以及SnS2与g-C3N4的质量比分别为0.15:1.0、0.1:1.0和0.15:1.0时，相应的TiO2/g-C3N4/LMS复合光催化剂对甲基橙(MO)及4-硝基酚表现出最佳降解活性，且均高于TiO2，g-C3N4以及g-C3N4/LMS。.以还原氧化石墨烯(RGO)为共复合物，采用乙醇热法制备了LMS/RGO杂化复合物，以此为共催化剂，TiCl4为钛源，采用液相剥离-乙醇热法制备了三元复合光催化剂TiO2/LMS/RGO。当MoS2、WS2及SnS2与RGO的质量比分别为2.5:2.5、2.0:2.5及3.0:2.5时，所得的TiO2/LMS/RGO光催化剂对罗丹明B(RhB)和4-硝基酚均表现出较高的光催化活性。.采用密度泛函理论(DFT)方法对TiO2/g-C3N4/LMS及TiO2/LMS/RGO复合光催化剂的结构进行分析，对TiO2与LMS(或RGO与LMS)之间的复合机理以及可能活性位点进行了探索，为高效光催化剂的设计提供有力的理论依据。