铁、钴配合物和有机-无机复合催化剂制备与选择性光催化CO2和醇转化为CO和醛研究

The application project, which involves studies on preparation of iron and nickel complex and composited catalysts and selectively photocatalytic conversion of CO2 and alchol into CO and aldehyde, respectively, will be focused on constructing two types of highly efficient and selective systems for the reduction of CO2 into CO using Fe(II, III), Co(II) complexes as catalytic centre. One is homogeneous system containing flexible triprydine ligand with functinal groups and functionalized Ru(II) complex used as photosensitizer, the other one is consisted of photosensitizer and free functionalized multiprydine ligand covalently linked to semiconductor oxide to form precursor of composited catalysts，which are obtained by reacting various metal centres, auxiliary ligands with precusor. The properties of photoinduced electron transfer for the photocatalytic systems will be investigated by transient absorption spectral changes. The effects of different types of proton/electron donors and their electronic factors as well as the interactions between auxiliary ligands, solvents, the functional groups on the ligands and CO2 on photocatalytic conversion and produt selectivity will be also carried out. In addition, the coupling redox reaction, which photocatalytic reduction of CO2 to CO and proton/electron dornor oxidized into desired product are driven simultaneously, is performed. The studies and results gained will bring further insight into the solution of the photocatalytic reduction CO2 and enviromental conditioning, and extend the documents of the related studies.

铁、钴配合物和有机-无机复合催化剂制备与选择性光催化CO2和醇转化为CO和醛研究申请项目，以带有功能团、柔性的三吡啶衍生物和辅配体的Fe、Co金属配合物分子作为催化活性中心，构建高效、高选择性、光催化CO2活化及转化为CO的分子催化体系；功能化的钌配合物和含有功能团的多联吡啶配体经半导体氧化物共价键合形成复合材料的前驱体，继而和金属离子和辅助配体以多种形式组装形成的有机-无机复合可见光催化体系。通过激发态吸收光谱研究光捕获体激发态电子向催化中心有效转移的调控因素，质子/电子给体种类与电子效应以及辅配体、溶剂、配体所带功能团和CO2作用的强弱对催化转化与产物选择性的影响。研究、实现高效光催化还原CO2为CO的同时，质子/电子给体选择性形成预期有机产物的耦合氧化还原反应。通过项目所涉及内容的研究，将为光催化CO2还原和经济环保体系的构建开辟新的研究思路和提供更多的实验依据。

太阳能驱动的二氧化碳转化为高附加值碳产品对减少二氧化碳排放，并以化学形式储存太阳能是一种诱人的策略。项目实施涉及到下述5方面研究，取得了相应的研究结果。（1）含有多联吡啶配体的Fe(II)、Co(II)分子催化剂合成与光催化CO2还原；（2）CoP/CdS在水相中光催化氧化芳醇为相应的醛和酮与水还原为氢气研究；（3）CoP、Co-Co2P与碳材料复合催化剂制备与光催化CO2还原反应体系构建；（4）CoO、Co3O4与CoP/SBA-15球形复合催化剂制备与光催化CO2还原为CO反应研究；（5）纳米Cu电催化氰基加氢及CO2调控选择性伯胺产生与反应过程。. 研究结果如下：（1）Fe(phen)3Cl2和[Fe(phen)2(EtOH)Cl]Cl有优异的光催化CO2转化活性，后者CO产物选择性达到95%，催化转化数和速率分别达到33167和4.61 s-1。（2）使用自制的CoP/CdS纳米光催化剂，在水相中可见光催化实现了醇氧化为醛和酮、水还原为氢气。机理研究表明，光催化水分解产生的羟基自由基是反应的驱动物种。（3）构建了含有CoP/碳纳米管、CoP/石墨烯，Co-Co2P@NPC以及CoO/、Co3O4/和CoP/球形SBA-15的两种新型催化体系。研究表明催化剂的杂化性质加速了电子的传递，提高了光催化CO2还原效率。在含有Co-Co2P@NPC的体系中，CO的平均生成速率为35000 µmol h-1g-1, 在反应持续3 h后的产物CO选择性为79.1%。而在第一个小时内，CO的线性生成速率达到63000 µmol h-1g-1。此外，我们发现在CO2饱和的KHCO3与小分子脂肪腈混合水溶液中，Cu催化剂对C≡N基的吸附抑制了电催化H2产生和CO2还原反应，而电解质中溶解的CO2与产物伯胺的NH2基团作用提高了C≡N基氢化成伯胺选择性。其中含羟基、羧基的脂肪腈伯胺产物选择性大于90%，电流效率为70~90%。