过渡金属掺杂TiO_2/活性炭复合体的制备及双协同光催化性能

Preparation of transition metal-doped TiO_2/activated carbon composite and two-synergies photocatalytic properties

以活性炭为载体,通过溶胶-凝胶法分别制备了Fe、Ag、Zn、Mn和Cr过渡金属离子掺杂TiO2/活性炭(X-TiO2/AC,X-TA;X:过渡金属离子)复合体,利用X射线衍射(XRD)、比表面积(BET)、X光电子能谱(XPS)、扫描电镜(SEM)、电子自旋共振谱(ESR)和荧光光谱(FS)对其结构进行表征.以罗丹明B的光催化降解为探针实验,评价掺杂负载型复合体的双协同光催化性能和使用寿命,提出双协同光催化扩增机制,并探讨了掺杂率和负载率对双协同扩增效果影响.结果表明:通过活性炭吸附和离子掺杂对TiO2光催化性能表现出双协同扩增作用,导致X-TA对罗丹明B的降解速率常数kapp大于掺杂X-TiO2粉体和TA负载体之和.同时,掺杂率和负载率共同影响协同效应,当Fe离子掺杂率和Fe-TiO2负载率分别为0.3%和10%时,Fe-TA复合体kapp最大为0.0208min-1.另外,过渡金属离子掺杂对TiO2光催化性能提高程度按掺杂离子Ag、Zn、Mn、Cr、Fe递增.掺杂后金属离子的价态、得电子能力、比表面积和掺杂TiO2颗粒尺寸上的差异决定了不同离子掺杂负载型复合体催化性能不同,复合体寿命降低的主要原因是由于活性组分从载体上流失所引起.

Using activated carbon,transition metal ions（Fe,Ag,Zn,Mn and Cr） as support and doped agent,respectively,the TiO2-coated active carbon doped with transition metal ion（X-TiO2/AC,X-TA;X：metal ion） was prepared via sol-gel method.The as-prepared photocatalysts were characterized by XRD,BET,XPS,SEM,ESR and FS.Photodegradation of Rhodamine B was used as probe reaction to examine for their photoactivity and evaluate their used times in photoreaction.The results show that photocatalytic degradation rate constant kapp of X-TA is higher than the sum of both X-TiO2 and TA due to duble synergic improvement effects of activated carbon and ion doping for TiO2 photoactivity.Maeanwhile,the doped ratio and coated ratio simultaneously affected synergic effect when the doped ratio of Fe ion and the coated ratio of Fe-TiO2 are 0.3% and 9%,respectively,Fe-TA composites have the maximum rate constant kapp of 0.0208.Additionally,the photoactivities of transition metalion-doped TiO are improved in the order of Ag,Zn,Mn,Cr and Fe.The photoactivity of transition metal ion-doped TiO2/AC appears to be a complex function of the nature of doped ions,capability of absorption electron,surface area of catalysts and size of transition metalion-doped TiO2 grains on activated carbon.The main cause of decrease of the catalyst age was the loss of active components from the carrier.