Preparation And Photocatalytic Properties Of Ferrite-based Photocatalytic Materials

Spinel ferrite is a new class of semiconductor materials, and can be excitedby light to catalyze the degradation of pollutants. Its band gap is small and it hasa higher utilization of sunlight and can become more efficient photocatalyst. Thespinel ferrite has the low photocatalytic effect when it degrades pollutants alone.In order to improve its activity, doping and precious metals deposition are used tomodify Spinel ferrite.In this study, YxZn_1-xFe₂O₄（Y=Ca, Cu and Ag） of different elements dopingand Ca_0.5Co_0.5Fe₂O₄obtained at different calcination temperatures and times weresynthesized through Sol-Gel method. X-ray diffraction（XRD） results showed thatthe Ca_xZn_1-xFe₂O₄produced the CaFe₂O₄peak with increasing the amount of Ca²⁺;the phase of CuxZn_1-xFe₂O₄was single, the diffraction peaks are not offset; Ag⁺was failed to enter the lattice, Fe₂O₃, Ag and ZnO impurity peaks appeared afterdoping Ag⁺; the Ca_0.5Co_0.5Fe₂O₄was spinel. The SEM results revealed that theCa²⁺doping leaded the appearance of spinel ferrite changing from granular to rod;the Cu²⁺doping decreased the particle size of spinel ferrite; the morphology ofAg⁺doping spinel ferrite was very irregular; the morphology of Ca_0.5Co_0.5Fe₂O₄was lamellar. The synthesized sample was used as the catalyst to degrade100mLmethyl orange （50mg/L） under UV irradiation. The photocatalytic experimentalresults showed that the methyl orange discoloration ratio of ZnFe₂O₄was62.88%;the methyl orange discoloration ratio of Ca_0.5Zn_0.5Fe₂O₄was85.25%; the methylorange discoloration ratio of Cu_0.1Zn_0.9Fe₂O₄was63.83%; the methyl orange dis-coloration ratio of Ag_0.1Zn_0.9Fe₂O₄was69.18%; the methyl orange discolorationratio of Ca_0.5Co_0.5Fe₂O₄calcined at850℃5h was94.2%.Au/ZnFe₂O₄was prepared by homogeneous deposition precipitation（HDP）and colloidal deposition（CD）. XRD analysis showed that Au diffraction peaksgradually increased with the increasing of the content of Au, Au/ZnFe₂O₄were successfully prepared. The SEM results showed that Au particles preparad byHDP was well dispersed than by CD, EDS analysis showed that the actual amountof Au was consistent with the theoretical calculation in the Au/ZnFe₂O₄preparedby HDP and CD. The photocatalytic experimental results showed that the methylorange discoloration ratio of Au/ZnFe₂O₄prepared by HDP was67.47%whencontent of Au was1wt%; the methyl orange discoloration ratio of Au/ZnFe₂O₄prepared by CD was72.17%when content of Au was5wt%.