Gorthy Rukmini, Krumdieck Susan, Bishop Catherine
Department of Mechanical Engineering, College of Engineering, University of Canterbury, 20 Kirkwood Ave, Christchurch 8041, New Zealand.
Materials (Basel). 2020 Apr 3;13(7):1668. doi: 10.3390/ma13071668.
The recent global pandemic of COVID-19 highlights the urgent need for practical applications of anti-microbial coatings on touch-surfaces. Nanostructured TiO is a promising candidate for the passive reduction of transmission when applied to handles, push-plates and switches in hospitals. Here we report control of the nanostructure dimension of the crystal plates in anatase columnar crystals as a function of the coating thickness. This nanoplate thickness is key to achieving the large aspect ratio of surface area to migration path length. TiO solid coatings were prepared by pulsed-pressure metalorganic chemical vapor deposition (pp-MOCVD) under the same deposition temperature and mass flux, with thickness ranging from 1.3-16 mm, by varying the number of precursor pulses. SEM and STEM were used to measure the plate width which is believed to be a key functional nano-dimension for photocatalytic activity. Competitive growth produces a larger columnar crystal diameter with thickness. The question is if the nano-dimension also increases with columnar crystal size. We report that the nano-dimension increases with the film thickness, ranging from 17-42 nm. The results of this study can be used to design a coating which has co-optimized thickness for durability and nano-dimension for enhanced photocatalytic properties.
近期全球新冠疫情凸显了在接触表面实际应用抗菌涂层的迫切需求。纳米结构的二氧化钛（TiO₂）在应用于医院的把手、推门板和开关时，是被动减少病毒传播的一个有前景的候选材料。在此，我们报告了锐钛矿柱状晶体中晶体板纳米结构尺寸随涂层厚度的变化情况。这种纳米板厚度是实现表面积与迁移路径长度的大长宽比的关键。在相同的沉积温度和质量通量下，通过脉冲压力金属有机化学气相沉积（pp-MOCVD）制备了TiO₂固体涂层，通过改变前驱体脉冲的数量，涂层厚度范围为1.3 - 16毫米。扫描电子显微镜（SEM）和扫描透射电子显微镜（STEM）用于测量板宽，板宽被认为是光催化活性的关键功能纳米尺寸。竞争生长导致柱状晶体直径随厚度增加。问题是纳米尺寸是否也会随着柱状晶体尺寸增加。我们报告纳米尺寸随膜厚增加，范围为17 - 42纳米。这项研究的结果可用于设计一种涂层，该涂层具有为耐久性而共同优化的厚度以及为增强光催化性能而优化的纳米尺寸。
