Preparation and photocatalytic properties of magnetically separatable ZnFe2O4-TiO2/reduced graphene oxide composites
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摘要: 以TiO2(P25)、Fe(NO3)39H2O、Zn(NO3)26H2O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。Abstract: 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.
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Key words:
- TiO2 /
- ZnFe2O4 /
- graphene /
- composites /
- photocatalysis
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