原位合成法制备TiO2负载酞菁钴催化剂用于CO2光催化还原反应

以钛酸正丁酯为原料采用原位化学合成的新方法,以二价钴离子为模板剂在TiO₂凝胶基质合成的同时,通过邻苯二腈的四聚反应将酞菁钴(CoPc)在TiO₂表面原位合成,得到均匀掺杂的CoPc/TiO₂光催化剂,用紫外-可见漫反射光谱、傅立叶变换-红外光谱等证实了CoPc的成功负载,并将其用于可见光下、水溶液中CO₂的还原反应,通过比较还原反应的效率,确定此光催化剂的最佳制备条件为:CoPc在TiO₂表面的摩尔负载量为3%,焙烧温度为200℃,溶胶搅拌时间为20 h,钛酸丁酯与邻苯二腈及钴离子同时加入溶胶体系中,采用此法制备的催化剂中CoPc酞菁环上的电子密度增加,有利于作为敏化剂的激发态CoPc向半导体TiO₂的导带注入电子,而且CoPc被均匀分散于TiO₂凝胶基质中,其上的“笼效应”有效避免了CoPc的迁移,使其二聚及多聚倾向大大减弱,此光催化剂用于CO₂光还原,在可见光照射下,水溶液中即可光还原CO₂为甲醇、甲醛、甲酸等产物,在光照反应10 h后总产量最高可达2903.83μmol/ g-catal。

Preparation of Titania-based CoPc Catalysts for CO2 Photocatalytic Reduction by the In-situ Method

Applying a new method of in-situ chemical synthesis through the annulation of 1,2-dicyanobenzene on the surface of TiO_2 with Co(Ⅱ) as template,cobalt phthalocyanine(CoPc) is synthesized in the processing of TiO_2 gel synthesis and obtained the catalyst of CoPc/TiO_2.CoPc is doped successfully and the catalysts are verified by means of UV-Vis and FT-IR.The optimum preparation conditions of CoPc/TiQ_2 are as follows:n(CoPc):n(TiO_2)=3:100,calcination temperature 200℃,stirring time 20 h,titanium tetra-butoxide,1,2-dicyanobenzene and cobalt ion adding at the same time.By this method the the electron density of Pc rings in CoPc is increased and favored to transfer electrons from excited CoPc to the conduction band of TiO_2.CoPc was isolated homogeneously in the pores of the titania matrix.This kind of"cage effect"effectively prevented the CoPc molecules from migrating to adjacent pores,thus decreasing the dimerization and aggregation of CoPc molecules.This catalyst can be apply to photocatalytic reduce CO_2,exposure under visible light,in the water solution,CO_2 can be reduced to HCHO,CH_3OH,HCOOH and so on.After 10 h of photo-reaction,the cumulative production can reach 2903.83μmol/g-catal.