Due to its physical and chemical stability in addition to its transparency in the visible region with ultraviolet protective activity, ZnO can be used in sunscreen applications. In our article, Na-doped zinc oxide nanoparticles were prepared in different concentrations by sol–gel and solvothermal techniques to reduce their photocatalytic activity. The photocatalytic activity of the doped samples was suppressed effectively at a concentration of 0.03 at% Na doping up to 90% by conducting the sol–gel process rather than the solvothermal process which resulted in about 70% photocatalytic reduction in a period of time from (0–30 min) when exposed to ultraviolet and visible light. In addition, the nanoparticles resulted by sol–gel route show a reduction in photoactivity under solar simulation about 98% rather than those resulted via solvothermal process which shows a reduction around 92% for 30 min which is the same period of time used for the photocatalytic degradation test. The particle size was around 64.6–84.6 nm for samples prepared by both methods.

中文翻译：

---

用于防晒应用的光催化活性降低的 Na 掺杂 ZnO 紫外线过滤器

由于其物理和化学稳定性以及在可见光区的透明性和紫外线防护活性，ZnO 可用于防晒应用。在我们的文章中，通过溶胶-凝胶和溶剂热技术制备了不同浓度的钠掺杂氧化锌纳米颗粒，以降低其光催化活性。掺杂样品的光催化活性在浓度为 0.03 at% Na 时被有效抑制，通过进行溶胶-凝胶过程而不是溶剂热过程，在一段时间内导致约 70% 的光催化还原（ 0-30 分钟），当暴露于紫外线和可见光时。此外，通过溶胶-凝胶途径产生的纳米颗粒在太阳模拟下显示出约 98% 的光活性降低，而不是通过溶剂热工艺产生的纳米颗粒在 30 分钟内降低约 92%，这与用于光催化降解测试的时间相同。两种方法制备的样品的粒径约为 64.6-84.6 nm。