Optimisation of HiPIMS photocatalytic titania coatings for low temperature deposition
Optimisation of HiPIMS photocatalytic titania coatings for low temperature deposition
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DOI：
10.1016/j.surfcoat.2014.02.020
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发表时间：
2014-07
影响因子：
5.4
通讯作者：
Marina Ratova;G. West;P. Kelly
中科院分区：
文献类型：
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作者：
Marina Ratova;G. West;P. Kelly
由于其高的光催化活性、稳定性和低的成本，呈球形的二氧化钛被广泛用于光催化应用。通过常规磁控溅射直接沉积的二氧化钛涂层倾向于具有非晶微观结构。为了形成纳米晶结构，通常需要衬底加热或沉积后热处理，其中纳米晶相通常在超过400 °C的温度下形成。根据驱动电压波形的性质，高功率脉冲磁控溅射（HiPIMS）已被证明可以向基底提供相对较低的热通量，同时仍然允许直接沉积结晶二氧化钛涂层。因此，该技术提供了直接在聚合物基材上存款光催化活性二氧化钛涂层的可能性，并因此开辟了一系列新的应用。在本工作中，一系列的二氧化钛薄膜沉积到玻璃基板上的HiPIMS为了研究各种工艺参数，如压力，脉冲频率和脉冲持续时间对涂层结构和光催化性能的影响。在紫外光和荧光灯照射下，通过降解有机染料亚甲基蓝的能力来评价涂层的光催化性能。通过在紫外/荧光光源下连续测定亚甲基蓝在665 nm处的吸收峰高，计算亚甲基蓝的降解速率。通过测量水滴在涂层表面的接触角，研究了涂层的亲水性能。在实验上，找到了使涂层光催化性能最大化的最佳条件，讨论了各种沉积参数对涂层的光催化性能和晶体结构的影响，然后将优化的涂层沉积到聚合物基底上，如聚对苯二甲酸乙二醇酯（PET）和聚碳酸酯，以评估使用这种方法对高能量，对于除玻璃之外的其它类型的基底，测试了光活性二氧化钛涂层的低温沉积和优化条件的相关性。结果发现，通过HiPIMS直接沉积到聚合物基底上的二氧化钛涂层在其沉积态下显示出相对高水平的活性。在足够低的温度下存款具有光催化功能的结晶二氧化钛的能力使得能够使用聚合物基底是该领域的重大进步。它可以潜在地允许在基底上生产大量的光催化材料，例如聚合物网，这是目前的沉积技术所不可能的。
Titanium dioxide in its anatase form is widely used in photocatalytic applications due to its high photocatalytic activity, stability and low cost. Titania coatings directly deposited by conventional magnetron sputtering tend to have an amorphous microstructure. For the anatase structure to develop, substrate heating or post-deposition thermal treatment is usually required, with the anatase crystal phase generally forming at temperatures in excess of 400 °C. This precludes the choice of thermally sensitive substrate materials for the photoactive coating.Depending on the nature of the driving voltage waveform, high power impulse magnetron sputtering (HiPIMS) has been shown to deliver a relatively low thermal flux to the substrate, whilst still allowing the direct deposition of crystalline titania coatings. Consequently, this technique offers the potential to deposit photocatalytically active titania coatings directly onto polymeric substrates and, therefore, opens up a range of new applications. In the present work a range of titanium dioxide thin films were deposited by HiPIMS onto glass substrates in order to study the influence of various process parameters, such as pressure, pulse frequency and pulse duration on coating structure and photocatalytic properties. The photocatalytic properties of the coatings were assessed by their ability to degrade the organic dye methylene blue under UV and fluorescent light irradiation. The degradation rate of methylene blue was calculated by measuring its absorption peak height at 665 nm in continuous mode under UV/fluorescent light source. The hydrophilic properties of the coatings were also investigated by measuring the contact angle of water droplets on the coating surfaces. Experimentally, the optimum conditions to maximise the photocatalytic performance of the coatings were found. The influence of various deposition parameters on the photocatalytic properties and crystal structure of the coatings is discussed.Optimised coatings then were deposited onto polymeric substrates, such as polyethylene terephthalate (PET) and polycarbonate, to assess the suitability of using this method for high-energy, low-temperature deposition of photoactive titania coatings and the relevance of the optimised condition was tested for other types of substrates other than glass. It was found that titania coatings deposited by HiPIMS directly onto polymeric substrates showed relatively high levels of activity in their as-deposited state.The ability to deposit crystalline titania with photocatalytic functionality at temperatures low enough to enable the use of polymer substrates is a significant advancement in the field. It could potentially allow the production of high volumes of photocatalytic material on substrates, such as polymer web, which is not possible with current deposition techniques.