What is a Photocatalyst?

About Photocatalyst

• The term photocatalyst is a combination of two words: photo, related to photon, and catalyst, which is a substance altering the reaction rate in its presence.
• Therefore, photocatalysts are materials that change the rate of a chemical reaction upon exposure to light. This phenomenon is known as photocatalysis. 
• The illumination of the catalyst causes the generation of free charges (electrons and holes) that can participate in chemical reactions, altering the reaction rate. 
• Photocatalysis includes reactions that take place by utilizing light and a semiconductor. All the photocatalysts are basically semiconductors.
• There are various materials that show photocatalytic capability, and titanium dioxide (TiO2) is said to be the most effective.
• The photocatalytic reactions can be categorized into two types based on the appearance of the physical state of the reactants.
  • Homogeneous photocatalysis: When both the semiconductor and reactant are in the same phase, i.e. gas, solid, or liquid.
  • Heterogeneous photocatalysis: When both the semiconductor and reactant are in different phases.
• It is valuable for applications like air and water purification, self-cleaning surfaces, and even in some aspects of solar energy conversion.

Q1) What are photons?

Photons are fundamental subatomic particles that carry the electromagnetic force — or, in simpler terms, they are light particles.he photon is also the "quantum," or fundamental unit, of electromagnetic radiation. Everyone is surrounded by photons: Like all other subatomic particles, photons exhibit wave-particle duality, meaning that sometimes they behave as tiny particles and sometimes they act as waves. Photons are massless, allowing them to travel at the speed of light in a vacuum.

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