Cappelletti Giuseppe, Ardizzone Silvia, Bianchi Claudia L, Gialanella Stefano, Naldoni Alberto, Pirola Carlo, Ragaini Vittorio
Nanoscale Res Lett. 2008 Nov 25;4(2):97-105. doi: 10.1007/s11671-008-9208-3.
Nanocrystalline TiO(2) samples were prepared by promoting the growth of a sol-gel precursor, in the presence of water, under continuous (CW), or pulsed (PW) ultrasound. All the samples turned out to be made of both anatase and brookite polymorphs. Pulsed US treatments determine an increase in the sample surface area and a decrease of the crystallite size, that is also accompanied by a more ordered crystalline structure and the samples appear to be more regular and can be considered to contain a relatively low concentration of lattice defects. These features result in a lower recombination rate between electrons and holes and, therefore, in a good photocatalytic performance toward the degradation of NO(x) in air. The continuous mode induces, instead, the formation of surface defects (two components are present in XPS Ti 2p(3/2) region) and consequently yields the best photocatalyst. The analysis of all the characterization data seems to suggest that the relevant parameter imposing the final features of the oxides is the ultrasound total energy per volume (E(tot)/V) and not the acoustic intensity or the pulsed/continuous mode.
通过在水存在的情况下，在连续波（CW）或脉冲波（PW）超声作用下促进溶胶 - 凝胶前驱体的生长，制备了纳米晶TiO₂样品。所有样品均由锐钛矿和板钛矿多晶型物组成。脉冲超声处理导致样品表面积增加和微晶尺寸减小，同时伴随着更有序的晶体结构，并且样品看起来更规则，可以认为含有相对低浓度的晶格缺陷。这些特性导致电子和空穴之间的复合率降低，因此，对空气中NOₓ的降解具有良好的光催化性能。相反，连续模式会诱导表面缺陷的形成（XPS Ti 2p(3/2)区域中存在两种成分），从而产生最佳的光催化剂。对所有表征数据的分析似乎表明，决定氧化物最终特性的相关参数是每体积的超声总能量（E(tot)/V），而不是声强或脉冲/连续模式。
