Alofi Saleh, O'Rourke Christopher, Mills Andrew
School of Chemistry and Chemical Engineering, Queens University Belfast, Stranmillis Road, Belfast BT9 5AG, U.K.
J Phys Chem C Nanomater Interfaces. 2023 Jun 20;127(25):12194-12205. doi: 10.1021/acs.jpcc.3c00952. eCollection 2023 Jun 29.
The kinetics of the removal of stearic acid (SA) islands by photocatalytic coatings is controversial, with some reporting that the islands fade as their thickness, , decreases with the irradiation time, , but maintain a constant area, , -d/d = 0, and others reporting that -d/d = 0 and -d/d = -constant, i.e., the islands shrink, rather than fade. This study attempts to understand the possible cause for these two very different observations through a study of the destruction of a cylindrical SA island and an array of such islands, on two different photocatalytic films, namely, Activ self-cleaning glass, and a P25 TiO coating on glass, which have established uniform and heterogeneous surface activities, respectively. In both cases, using optical microscopy and profilometry, it is shown that, irrespective of whether there is as a single cylindrical island or an array of islands, decreases uniformly with , -d/d = constant, and -d/d = 0, so that the SA islands just fade. However, in a study of the photocatalyzed removal of SA islands with a volcano-shaped profile, rather than that of a cylinder, it is found that the islands shrink and fade. A simple 2D kinetic model is used to rationalize the results reported in this work. Possible reasons for the two very different kinetic behaviors are discussed. The relevance of this work to self-cleaning photocatalytic films is discussed briefly.
光催化涂层去除硬脂酸（SA）岛状物的动力学存在争议，一些研究报告称，随着照射时间(t)的增加，这些岛状物会褪色，因为它们的厚度(h)会减小，但面积(A)保持不变，即(-dA/dt = 0)；而另一些研究则报告称(-dA/dt = 0)且(-dh/dt = -常数)，也就是说，岛状物会收缩而不是褪色。本研究试图通过研究圆柱形SA岛状物以及此类岛状物阵列在两种不同光催化薄膜上的破坏情况，来理解这两种截然不同的观察结果可能的原因。这两种光催化薄膜分别是Activ自清洁玻璃和玻璃上的P25 TiO涂层，它们分别具有均匀和不均匀的表面活性。在这两种情况下，通过光学显微镜和轮廓仪测量表明，无论存在单个圆柱形岛状物还是岛状物阵列，(h)都随(t)均匀减小，(-dh/dt = 常数)且(-dA/dt = 0)，因此SA岛状物只是褪色。然而，在一项关于光催化去除具有火山形状轮廓而非圆柱形轮廓的SA岛状物的研究中，发现这些岛状物会收缩并褪色。使用一个简单的二维动力学模型来解释本工作中报告的结果。讨论了两种截然不同的动力学行为的可能原因。简要讨论了本工作与自清洁光催化薄膜的相关性。
