温和条件下CoPc/TiO_2光催化还原CO_2

采用浸渍法制备的TiO2负载钴酞菁(CoPc/TiO2)为光催化剂,在碱性水溶液中、可见光照下,CO2可被光催化还原为产物HCOOH、CO、CH4。对催化剂的制备条件进行了考察,在m(CoPc)∶m(TiO2)=1∶100、催化剂浸渍时间12 h、浸渍溶剂为甲苯、催化剂焙烧温度200℃的条件下,还原总产物量最高可达1 075.38μmol/g-cat,其中甲酸为主产物,最高可达708.54μmol/g-cat。对催化剂进行了XRD、DRS表征,证实了CoPc在TiO2表面的负载。结果表明:用该催化剂在可见光照及常温常压下,于水溶液中就可将CO2还原。其次,实验还发现光照下可产生电子转移,实现了电荷的重新分配,以降低电子-空穴的重新结合;TiO2表面应有一定的空隙率,有利于CO2在其表面获得电子被还原。

Photocatalytic Reduction of Carbon Dioxide over CoPc/TiO2 under Mild Conditions

Carbon dioxide was photocatalytically reduced to HCOOH,CO and CH_4 in caustic solution under visible light irradiation.Cobalt phthalocyanine loaded on TiO_2(CoPc/TiO_2) was prepared by impregnation and used as photocatalyst.The optimum preparation conditions were:m(CoPc)∶m(TiO_2)=1∶100,time of impregnation 12 h,toluene as solvent and baking temperature 200 ℃.Total yield of the photocatalysis products reached(1 075.38) μmol/g-cat after 10 h of irradiation.The main product HCOOH can reach 708.54 μmol/g-cat.XRD and DRS revealed that most CoPc clusters were on the TiO_2 surface.Experimental results indicated that under visible light this catalyst can reduce CO_2 in water solution.The irradiation leads to transfer of electron and redistribution of electric charge.The photocatalytic efficiency of CoPc/TiO_2 was markedly increased because of lowering of re-combination probability of the hole-electron pairs.In addition,there should be some gaps on the surface of TiO_2 so that CO_2 can be reduced on the surface of TiO_2 resulting from getting the electrons.