空穴调控的阴阳离子共掺杂TiO2 高可见光催化性能的理论研究

(限3000 Characters)：The passivated codoping approach and the noncompensated anion-cation codoping one are typical methods used in designing ions-codoped TiO2 materials. However，which approach is more advantageous in promoting their photocatalitic activity is still disputable. There is also controversy on the band gap states caused by codoping: some researchers suggested that they were positive to enhance the visible light photocatalitic efficiency, while others disagreed about this point. The argument has been an obstacle to develop novel TiO2-based photocatalysts. Therefore, based on the aim of hydrogen production through the photoelectrochemical water splitting, a new programme satifying with the optimal codoping method has been proposed, and the N/C-M（Cr、Mo、W）codoped TiO2 including holes with various ratios of anions to cations will be systematically investigated using the first-principles calculations in the project. The models of ions-codoped TiO2 will be constructed through adjusting the ratios of anions to cations, and then all the modeled systems are calculated. Finally, a rational program will be screened out, which is different from the present methods, and the doped systems whose band gap states serve to promote their photocatalitic activity are obtained, offering a new way to design TiO2-based high-performance photocatalysts.

(限400 字)：离子钝化共掺杂和离子非补偿性共掺杂是目前比较盛行的两种离子共掺杂TiO2的方法。然而哪种方法更有利于光催化活性的提高尚存争议。其中对共掺杂引起的带隙态，有研究者认为它不利于可见光催化效率的提高，也有人认为对可见光催化活性起促进作用。这两种不一致的观点影响了离子共掺杂方案的确定，不利于新型光催化剂的开发。因此本项目基于光催化制氢的目的提出满足最佳离子共掺杂方法的新方案，采用第一性原理计算对含空穴的N/C-M（Cr、Mo、W）阴阳离子共掺杂的TiO2展开系统的理论模拟研究，首先构建含不同阴阳离子配比的掺杂模型，然后通过计算研究筛选出不同于当前两类配比方法的合理方案，找到带隙态并不总是起抑制光催化活性作用的实例，为高性能TiO2基光催化材料的设计提供新思路。

离子钝化共掺杂和离子非补偿性共掺杂是目前比较盛行的两种离子共掺杂TiO2的方法。然而哪种方案更有利于光催化活性的提高尚存争议。对共掺杂引起的带隙态，有研究者认为它不利于可见光催化效率的提高，也有人认为对可见光催化活性起促进作用。这两种不一致的观点影响了离子共掺杂方案的确定，不利于新型光催化剂的开发。为解决这一难题，本课题基于光催化制氢机理，提出满足最佳离子共掺杂方案的新标准：掺杂体系（确保其稳定存在）的电子结构应是其价带被尽量抬高而导带不受影响，同时在带隙中或价带边引进态密度强度相对较大和离域性相对较强的电子态。.本项目采用基于密度泛函理论的第一性原理计算对N/C-M（Cr、Mo、W）阴阳离子共掺杂的TiO2展开系统的理论模拟研究。首先构建含不同阴阳离子配比的掺杂模型；然后通过计算研究筛选出不同于当前两类配比方法的合理方案，即N-（Mo和W）阴阳离子配比为3:1的掺杂体系，该体系相对稳定，其电子结构性质与本课题提出的假设相符；最后结合已有实验数据，系统研究了N、NH和N2H掺杂的体系，通过计算确定了N2H掺杂体系的计算结果与实验相符，找到了带隙态并不总是起抑制光催化活性作用的实例，这从实验和理论方面进一步验证了该假设的正确性。这些研究成果将为高性能TiO2基制氢光催化剂的设计提供新思路。