可磁分离ZnFe2O4-TiO2/还原氧化石墨烯复合材料的制备及光催化性能

以TiO2(P25)、 Fe(NO3)3·9H2O、 Zn(NO3)2·6H2O和氧化石墨烯(GO)为原料,通过一步溶剂热法合成可磁分离的ZnFe2O4-TiO2/还原氧化石墨烯(rGO)复合材料。采用UV-Vis、 Raman、 XRD、 SEM和EDS对ZnFe2O4-TiO2/rGO复合材料进行表征,并研究不同rGO比例的ZnFe2O4-TiO2/rGO对模拟染料废水亚甲基蓝(MB)的光催化降解性能。GO在溶剂热反应过程中,被还原成rGO。由于ZnFe2O4和rGO的加入,不仅使ZnFe2O4-TiO2/rGO实现对可见光的吸收,而且使其具有磁性,便于分离和回收利用。当GO质量分数为5wt%时, ZnFe2O4-TiO2/rGO显现出对MB最佳的光催化活性, 60 min光照后的降解率达到99.1%。通过光催化活性物种捕获实验得出ZnFe2O4-TiO2/rGO复合材料降解MB的过程中,活性物种主要为·OH和·O2-, TiO2导带(CB)中的光生电子(e+)转移到ZnFe2O4的价带(VB),遵循Z型转移机制。光催化剂稳定性实验表明, ZnFe2O4-TiO2/rGO复合材料具有优越的稳定性,可作为太阳光照射下降解有机染料的光催化剂。

Preparation and photocatalytic properties of magnetically separatable ZnFe2O4-TiO2/reduced graphene oxide composites

ZnFe₂O₄-TiO₂/reduced graphene oxide(rGO) composites were synthesized from TiO₂(P25), Fe(NO₃)₃·9H₂O, Zn(NO₃)₂·6H₂O and graphene oxide (GO) by one-step solvent thermal method. The properties and structures of ZnFe₂O₄-TiO₂/rGO composites were characterized by UV-Vis, Raman spectra, XRD, SEM and EDS. The photocatalytic degradation performance of ZnFe₂O₄-TiO₂/rGO composites prepared with different amount of GO were investigated. GO is reduced to rGO in the solvent thermal reaction process. The addition of ZnFe₂O₄ and rGO broadens the visible light wavelengths absorbed by ZnFe₂O₄-TiO₂/rGO composites. ZnFe₂O₄-TiO₂/rGO composites have magnetic performance, which is convenient for separation and recycling. ZnFe₂O₄-TiO₂/rGO composites show the best photocatalytic degradation of methylene blue(MB) when the mass fraction of GO is 5wt%, and the degradation rate reaches 99.1% after 60 min under simulated solar irradiation. According to the scavenger experiments, the possible MB degradation mechanism is mainly contributed to the generation of active species induced by·OH and·O2-. The photo-generated electrons(e+) in conduction band(CB) of TiO₂ migrate to valence band(VB) of ZnFe₂O₄, and form a Z-scheme photocatalytic system. The photocatalyst stability test shows that ZnFe₂O₄-TiO₂/rGO composites have excellent stability and can be used as a photocatalyst for the degradation of organic dyes under sunlight.