基于晶面与氧物种的结构匹配性设计高效可见光催化剂

The catalytic degradation of organic pollutants and photocatalytic water splitting for hydrogen (oxygen) evolution over semiconductors under sunlight are important routes to resolve environmental pollution and energy crisis. It is very important for photocatalytic techniques applied in industry to study catalytic mechanism. The design of crystal facets and morphological control are commonly employed strategies to optimize the performance of various semiconducting crystalline catalysts. The conventional understanding of the surface atomic structure of a crystal is that facets with a higher percentage of undercoordinated atoms are usually more reactive in heterogeneous reactions. We think that the geometrical correspondence between the facets of the catalysts and the structures of the active oxygen species will exert a great influence on the the reactivity except for the reported factors such as surface atomic structure and electronic structure. In view of the few studies for the interface and low photocatalytic activity under visible irradiation，the effect of the geometrical correspondence between the facets of the catalysts and the structures of the reactive species, including bond length and bond angles of H2O, O2,oOH and oO2- on the reactivity would be studied for CdS visible photocatalysts, and the relationship between surface structures of the catalysts and catalytic activity will be induced. Therefore，high efficient catalysts with high energy facet used for degradation of organic pollutants and hydrogen evolution under the visible irradiation will be designed. The findings of this work will open up new opportunities for maximizing photoreactivity through morphological control of photocatalysts. Except for the structure design and surface modification to improve photocatalytic performance of CdS, metal ions doping (such as Mn, Ni,etc.) is demonstrated to control the bandgap and absorption properties, especially Ni2+ doping, which is able to improve the photoactivity of photocatalysts. However, studies on why doping will lead to improvement of photoactivity have not been explored in detail based on atomic structures of photocatalysts modified by dopants. The design and fabrication of photocatalysts based on structural matches between catalysts and oxygen species will be useful for exploring high efficient visible-light driven catalysts.

对光催化作用机理认识的不足已成为制约光催化技术工业化的瓶颈。光催化反应属于多相界面作用，目前有关催化剂晶面对光生载流子的形成及扩散等影响研究较多，而对载流子如何高效地活化氧物种以大量产生自由基等界面作用行为的研究还不够。项目基于晶体的各向异性生长特点及多位催化理论，提出催化剂所暴露晶面的几何因素（原子间距、原子的排列方式）与氧物种（H2O、O2等）结构（键长、键角）的匹配性是影响氧物种的吸附与活化及自由基的产生与光催化活性的关键因素。拟以CdS为研究对象，结合理论计算，探讨结构匹配性与光催化活性的关联关系。鉴于离子掺杂能调变材料的表面结构，在CdS中掺杂Ni2+等，剖析掺杂对匹配度的改变及催化活性的影响。在采用NMR技术等研究纳米晶成核与生长机理的基础上，根据匹配度设计制备高比例暴露活性晶面的CdS催化剂,并通过非原位负载法改善CdS的稳定性，为揭示界面在光催化反应中的重要作用提供新思路。

自1972年日本的Fujishima和Honda在Nature上报道TiO2光催化剂催化水分解制氢以来，作为一种解决能源与环境问题的有效手段，通过光催化技术处理废水、废气处理及光解水制氢的研究引起了广泛关注。但由于还存在不能充分利用太阳光、光催化效率低及催化剂的回收再利用避免二次污染等问题，实现光催化剂在实际生产中的应用还存在差距，制备获得高效、价廉的光催化剂是亟待解决的关键技术。.由于TiO2光催化剂仍存在禁带宽度大不能充分利用太阳光及光催化效率低等缺点，除了对其改性外，发展新型可见光催化剂是重要的研究方向。铋系半导体材料因其来源丰富、对可见光响应良好及光催化性能优异，近几年引起研究者重视。尽管已有大量相关报道，但由于便宜易得的原料Bi(NO3)3·5H2O易水解，在室温下难以制备获得形貌及微结构均匀的产物。所以合成反应大多在水热法条件下进行，不利于大规模生产。本项目的创新点及突破的关键技术之一是通过选择合适的溶剂，使得大部分合成反应在室温下进行，解决了硝酸铋容易水解而难以进行均相合成的问题；创新点及关键技术之二，由于铋基化合物的层状结构特点，易呈片状形貌，导致性能单一，本项目获得了丰富形貌的产物，如HCOO(BiO)超长纳米纤维，网络状Bi纳米线等，使得铋基化合物的微观结构及性能更加丰富；创新点及关键技术之三，开发了几种性能优异的新型铋基光催化剂，如醋酸氧铋（CH3COO(BiO)），一种碱式硝酸铋等（ [Bi6O6(OH)2](NO3)4·2H2O），丰富了铋系光催化剂体系。关键技术之四，通过微结构调控，获得了性能优异的几种铋基光催化剂，详细研究了铋系催化剂的微观结构、粒径及形貌与光催化性能的构效关系，并探讨了光催化机理。.在经费支持下，在国际一流期刊Nanoscale, J.Mater.Chem.A, Chem.Eng.J等上发表SCI收录论文17篇，获授权发明专利2件，超额完成了合同所预期的指标。培养硕士及博士研究生12名，有一名硕士的论文被评为江苏省优秀硕士论文。