卤素调控原子尺度卤化氧铋材料的构筑及其增强光催化CO2还原研究

Photocatalytic reduction of CO2 into carbon-containing fuels is an effective way to realize the solar energy conversion and storage, which has arouse more and more attentions in addressing energy and environmental issues. In this project, long carbon chain alkyl quaternary ammonium, pyridine, imidazole and other organic halides are employed to construct functional reactive halogen ionic liquids. The cations of these special ionic liquids have surfactant function and the anions have the controlled release ability of halogen. Atomically-thick bismuth oxyhalide materials are controlled prepared by using ionic liquids as surfactant and halogen source. Through precisely adjustment of different pH values or calcination temperatures, the halogens in the obtained atomically-thick bismuth oxyhalide materials are further removed to achieve the atomically-thick dehalogenation bismuth oxyhalide materials with different halogen content. Such materials have a controlled bandgap, adjustable band edge, high electron-hole separation efficiency and other characteristics, achieving high efficiency and high selectivity photocatalytic reduction of CO2. The intrinsic relationships between the composition, structure, surface characteristic of the materials and photoreduction activity, selectivity will be explored. The photocatalytic reduction process of CO2 will be studied by in situ spectroscopy and theoretical calculation, along with the photocatalytic mechanism may be revealed.

光催化CO2还原是实现太阳能转换与能量存储的有效途径之一，在解决能源与环境问题方面受到越来越多的关注。本课题拟采用长碳链烷基季铵、吡啶、咪唑等有机物与卤化物构筑功能化可反应卤素离子液体。该类离子液体阳离子具有表面活性功能，阴离子具有卤素控制释放功能，以其为源可控制备原子级厚卤化氧铋材料。通过溶液pH调控或梯度热处理策略，实现原子级厚卤化氧铋材料卤素精确裁剪脱除，制得卤素含量和能带可调原子级厚卤化氧铋材料。该类材料具有可调控的带宽和带边位置，以及高电子空穴分离效率等特点，能实现光催化CO2转化过程催化活性和产物选择性的双重提升。系统研究卤素可调原子级厚卤化氧铋材料的组成、结构、表面性质与光催化还原CO2的活性，还原产物选择性之间的内在关系。通过原位谱学及理论计算方法研究光催化过程中CO2还原转化的途径和影响因素，总结归纳出可能的光催化还原机理。

本课题研究主要围绕卤素调控原子尺度卤氧铋材料的构筑及其增强光催化CO2还原性能研究。主要运用表面缺陷、单原子掺杂、形貌调控和异质结构建等策略来设计光催化材料。已成功制备出单原子Co掺杂单晶胞Bi3O4Br、富氧缺陷双层Bi12O17Cl2纳米管、Bi4O5I2中空纳米管、碳聚合物点/PbBiO2Br复合材料、富“Bi-O”缺陷的Bi2MoO6超薄纳米片、不同官能团修饰的黑磷纳米片。通过X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）和比表面积测试（BET）等表征手段对所制备材料的结构与形貌进行了表征，并对其进行光催化性能探究。实验结果表明，所制备的单原子Co掺杂单晶胞Bi3O4Br、富氧缺陷双层Bi12O17Cl2纳米管、碳聚合物点/PbBiO2Br复合材料展现出较好的光催化CO2还原性能；此外，表面富“Bi-O”缺陷的Bi2MoO6超薄纳米片相比于少缺陷的Bi2MoO6材料展现出显著增强的光催化CO2还原性能；相比于单层黑磷（BP）纳米片及-NH2和-F修饰的黑磷纳米片，羟基修饰的黑磷纳米片具有出色的光催化CO2还原活性和稳定性。本课题通过采用多种调控策略，成功实现了高光催化性能的卤氧铋及其复合光催化剂的设计与可控制备。研究了不同策略制备的光催化剂的活性机理，并结合材料的结构与光催化活性结果，阐述了材料的构效关系。