光触媒必须在紫外线的照射下才能发挥作用。如果不能获得太阳光照，若想激活光触媒，则必须另外加上紫外灯。紫外灯的选择应该是254nm或者365nm的效果比较好。至于在自然光和日光灯等微弱光源甚至是无光的条件下，光触媒是不能正常发挥功效的。那种所谓的无光条件下发挥作用的“冷触媒”已然失去了“光触媒”的真正含义。但是过多的紫外线对人体有伤害。光触媒技术其实是靠紫外线照射光触媒网上的氧化钛离子，使其激活进而氧化接触到其表面的细菌。
Photocatalysts must be exposed to ultraviolet radiation to work. If you can't get sunlight, if you want to activate the photocatalyst, you have to add an ultraviolet lamp. The choice of UV lamp should be 254nm or 365nm. As for the weak light source such as natural light and fluorescent lamp, even without light, photocatalyst can not work normally. The so-called "cold catalyst" which works under no light conditions has lost its real meaning. But too much ultraviolet radiation is harmful to the human body. In fact, photocatalyst technology is to irradiate titanium oxide ions on the photocatalyst network by ultraviolet radiation, so that it can activate and then oxidize the bacteria that contact its surface.