National Institute for R &D of Isotopic and Molecular Technology, 67 - 103 Donat St., 400293 Cluj-Napoca, Romania.
National Institute for R &D of Isotopic and Molecular Technology, 67 - 103 Donat St., 400293 Cluj-Napoca, Romania.
J Colloid Interface Sci. 2019 Apr 15;542:296-307. doi: 10.1016/j.jcis.2019.02.026. Epub 2019 Feb 7.
Interface modified SnO-TiO composite nanoparticles were produced in two stages: first SnO nanoparticles were prepared by chemical precipitation in the presence of polyvinylpyrrolidone (PVP) and thermally treated at 500 °C then TiO was deposited on top of modified SnO and followed by a final annealing. As a consequence SnO-TiO composite nanoparticles get crystallized while PVP is decomposed into monomer units and other attached smaller molecular fragments. TGA coupled with FT-IR spectroscopy confirmed the presence of monomers and other moieties as a result of PVP thermal fragmentation. The crystalline phases and composition of the two oxides were evidenced by X-ray diffraction, HRTEM and XPS. It was found that specific surface area of the composites increases with the increase in the initial amount of PVP. Also, the oxidation potential of the TiO shell, as determined by UV photoelectron spectroscopy (UPS), significantly decreases as the PVP quantity increase and further modifies the band alignment between SnO and TiO components. Additionally, both XPS and UPS spectra as well as EPR investigations indicate the presence of many localized states inside the band gap of TiO. With a moderate PVP content the combined effects of band alignment, gap localized states and porosity make possible an increased number of reactive oxygen species (ROS) generation thus increasing photocatalytic activity against RhB dye solution under visible irradiation. The photocatalytic mechanism was elucidated based on the identification of radical species involved and in accordance with energy bands alignment, gap states, and porosity. Besides water purification by photocatalysis, SnO-TiO as ROS generating heterostructures may be used in applications like antibacterial and antitumoral, deodorizing, air purifying, self-cleaning, gas sensing, as well as in hydrogen production.
界面改性 SnO-TiO 复合纳米粒子分两步制备：首先在聚维酮（PVP）存在下通过化学沉淀法制备 SnO 纳米粒子，并在 500°C 下进行热处理，然后将 TiO 沉积在改性 SnO 上，最后进行退火。结果，SnO-TiO 复合纳米粒子在 PVP 分解成单体单元和其他较小的附着分子片段的同时结晶。TGA 与 FT-IR 光谱联用证实了 PVP 热解产生单体和其他基团的存在。两种氧化物的晶相和组成通过 X 射线衍射、高分辨透射电子显微镜和 X 射线光电子能谱得到证实。发现复合材料的比表面积随 PVP 初始用量的增加而增加。此外，通过紫外光电子能谱（UPS）确定的 TiO 壳的氧化电位随着 PVP 量的增加而显著降低，进一步改变了 SnO 和 TiO 组分之间的能带排列。此外，XPS 和 UPS 光谱以及 EPR 研究表明，TiO 带隙内存在许多局域态。在适度的 PVP 含量下，能带排列、带隙局域态和多孔性的综合效应使得生成更多的活性氧物种（ROS）成为可能，从而在可见光照射下提高了对 RhB 染料溶液的光催化活性。根据所涉及自由基物种的鉴定以及与能带排列、隙态和多孔性的一致性，阐明了光催化机制。除了通过光催化进行水净化外，SnO-TiO 作为 ROS 产生的异质结构还可用于抗菌和抗肿瘤、除臭、空气净化、自清洁、气体传感以及制氢等应用。
