Valokatalyysejä

Valokatalyysejä, or photocatalysis in English, is a chemical process where a catalyst is activated by light. This light energy is absorbed by the photocatalyst, promoting it to a higher energy state. This excited state allows the photocatalyst to initiate or accelerate a chemical reaction that would otherwise be slow or not occur at all. The photocatalyst itself is not consumed in the process; it facilitates the reaction and returns to its original state.

Commonly used photocatalysts include titanium dioxide (TiO2), which is stable, non-toxic, and efficient in the presence of ultraviolet (UV) light. Other materials like zinc oxide (ZnO), cadmium sulfide (CdS), and various metal oxides and nitrides are also employed, often tailored for specific applications and light sources.

The applications of valokatalyysi are diverse and growing. One of the most significant is environmental remediation, where photocatalysis is used to break down pollutants in air and water, such as volatile organic compounds (VOCs), dyes, and pesticides. Another area is self-cleaning surfaces, where a photocatalytic coating on materials like glass or tiles can decompose organic dirt and grime when exposed to light. In the field of energy, photocatalysis is explored for the production of hydrogen fuel from water splitting and for CO2 reduction into valuable chemicals. It also finds use in sterilization and disinfection processes. The efficiency of photocatalysis depends on factors like the light intensity and wavelength, the properties of the photocatalyst, and the reaction conditions.