Department of Materials Science and Engineering, Kangwon National University, Samcheok-si, 271 Kangwon-do, Republic of Korea; School of Chemistry, University of Witswatersrand, Johannesburg WITS 2050, South Africa.
Department of Chemical Engineering, Hanyang University, 1271 Sa 3 dong, Sangnok-gu, Ansan-si, Gyeongi-do 426-791, Republic of Korea; Department of Chemistry, Mkwawa College, University of Dar es Salaam, Iringa, United Republic of Tanzania.
J Colloid Interface Sci. 2015 Mar 15;442:1-7. doi: 10.1016/j.jcis.2014.11.060. Epub 2014 Dec 3.
TiO2 photocatalysts with a mixture of different TiO2 crystal polymorphs have customarily been synthesized hydrothermally at high temperatures using complicated and expensive equipment. In this study TiO2 nanoparticles with a mixture of TiO2 crystals were synthesized using a modified sol-gel method at low temperature. In order to form nanoparticles with different polymorphs a series of samples were obtained at pH 2, 4, 7 and 9. Raw samples were calcined at different temperatures ranging from 200 to 800°C to evaluate the effect of the calcination temperature on the physico-chemical properties of the samples. XRD results revealed that a mixture of anatase and brookite can be obtained in the as-synthesized samples and in those calcined up to 800°C depending on the pH used to obtain the final product. Indeed, a mixture of anatase brookite and rutile; or a sample with only rutile phase can be yielded through further calcination of the as-prepared samples at temperatures ⩾600°C due to phase transformation. The photocatalytic performance of the samples with a mixture of anatase-brookite; anatase-brookite-rutile; and anatase-rutile (Degussa P25 TiO2) was exquisitely investigated in the degradation of methylene blue solutions. The samples obtained at pH 2 and calcined at 200°C possessed the highest activity of all due to its superior properties. This study elucidates a facile method suitable for the synthesis of TiO2 with different mixtures of TiO2 polymorphs with desirable properties for various applications.
具有不同 TiO2 晶体多晶型混合物的 TiO2 光催化剂通常是在高温下使用复杂且昂贵的设备通过水热法合成的。在这项研究中，使用改良的溶胶-凝胶法在低温下合成了具有 TiO2 晶体混合物的 TiO2 纳米粒子。为了形成具有不同多晶型的纳米粒子，在 pH 值为 2、4、7 和 9 下获得了一系列样品。原始样品在 200 至 800°C 的不同温度下煅烧，以评估煅烧温度对样品物理化学性质的影响。XRD 结果表明，在合成样品中和在煅烧至 800°C 的样品中，可以获得锐钛矿和板钛矿的混合物，这取决于用于获得最终产物的 pH 值。实际上，通过在 ⩾600°C 的温度下进一步煅烧，由于相变，可以得到锐钛矿-板钛矿-金红石的混合物；或仅具有金红石相的样品。具有锐钛矿-板钛矿混合物；锐钛矿-板钛矿-金红石；和锐钛矿-金红石（Degussa P25 TiO2）的样品的光催化性能在亚甲基蓝溶液的降解中进行了细致的研究。由于其优越的性质，在 pH 值为 2 且在 200°C 下煅烧的样品具有最高的活性。本研究阐明了一种适用于合成具有不同 TiO2 多晶型混合物的 TiO2 的简便方法，这些混合物具有各种应用所需的理想性质。
