Wysocka Izabela, Kowalska Ewa, Trzciński Konrad, Łapiński Marcin, Nowaczyk Grzegorz, Zielińska-Jurek Anna
Faculty of Chemistry, Gdansk University of Technology, 80-233 Gdansk, Poland.
Institute for Catalysis (ICAT), Hokkaido University, Sapporo 001-0021, Japan.
Nanomaterials (Basel). 2018 Jan 7;8(1):28. doi: 10.3390/nano8010028.
The combination of TiO₂ photocatalyst and magnetic oxide nanoparticles enhances the separation and recoverable properties of nanosized TiO₂ photocatalyst. Metal-modified (Me = Pd, Au, Pt, Cu) TiO₂/SiO₂@Fe₃O₄ nanocomposites were prepared by an ultrasonic-assisted sol-gel method. All prepared samples were characterized by X-ray powder diffraction (XRD) analysis, Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), Mott-Schottky analysis and photoluminescence spectroscopy (PL). Phenol oxidation pathways of magnetic photocatalysts modified with Pt, Pd, Cu and Au nanoparticles proceeded by generation of reactive oxygen species, which oxidized phenol to benzoquinone, hydroquinone and catechol. Benzoquinone and maleic acid were products, which were determined in the hydroquinone oxidation pathway. The highest mineralization rate was observed for Pd-TiO₂/SiO₂@Fe₃O₄ and Cu-TiO₂/SiO₂@Fe₃O₄ photocatalysts, which produced the highest concentration of catechol during photocatalytic reaction. For Pt-TiO₂/SiO₂@Fe₃O₄ nanocomposite, a lack of catechol after 60 min of irradiation resulted in low mineralization rate (CO₂ formation). It is proposed that the enhanced photocatalytic activity of palladium and copper-modified photocatalysts is related to an increase in the amount of adsorption sites and efficient charge carrier separation, whereas the keto-enol tautomeric equilibrium retards the rate of phenol photomineralization on Au-TiO₂/SiO₂@Fe₃O₄. The magnetization hysteresis loop indicated that the obtained hybrid photocatalyst showed magnetic properties and therefore could be easily separated after treatment process.
二氧化钛光催化剂与磁性氧化物纳米颗粒的结合提高了纳米二氧化钛光催化剂的分离和可回收性能。采用超声辅助溶胶-凝胶法制备了金属改性（Me = Pd、Au、Pt、Cu）的TiO₂/SiO₂@Fe₃O₄纳米复合材料。通过X射线粉末衍射（XRD）分析、布鲁诺尔-埃米特-泰勒（BET）法、X射线光电子能谱（XPS）、扫描透射电子显微镜（STEM）、莫特-肖特基分析和光致发光光谱（PL）对所有制备的样品进行了表征。用Pt、Pd、Cu和Au纳米颗粒改性的磁性光催化剂的苯酚氧化途径是通过产生活性氧物种进行的，活性氧物种将苯酚氧化为苯醌、对苯二酚和邻苯二酚。苯醌和马来酸是对苯二酚氧化途径中的产物。观察到Pd-TiO₂/SiO₂@Fe₃O₄和Cu-TiO₂/SiO₂@Fe₃O₄光催化剂的矿化率最高，它们在光催化反应过程中产生的邻苯二酚浓度最高。对于Pt-TiO₂/SiO₂@Fe₃O₄纳米复合材料，照射60分钟后没有邻苯二酚，导致矿化率较低（形成CO₂）。有人提出，钯和铜改性光催化剂的光催化活性增强与吸附位点数量的增加和有效的电荷载流子分离有关，而酮-烯醇互变异构平衡阻碍了Au-TiO₂/SiO₂@Fe₃O₄上苯酚光矿化的速率。磁化滞后回线表明，所制备的杂化光催化剂具有磁性，因此在处理过程后可以很容易地分离出来。
