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Photocatalysis

2023 JAN 14

Preliminary   > Science and Technology   >   Innovation and New technologies   >   Innovation and New technologies

Why in news?

  • Recently, a study has reported a way to achieve a relatively high efficiency in an artificial photosynthesis reaction in which water is split into oxygen and hydrogen using sunlight and a catalyst. The technique is called photocatalysis.

What is Photocatalysis?

  • 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 on exposure to light. This phenomenon is known as photocatalysis.
  • Photocatalysis includes reactions that take place by utilizing light and a semiconductor.
  • The substrate that absorbs light and acts as a catalyst for chemical reactions is known as a photocatalyst.
  • All the photocatalysts are basically semiconductors.
  • Photocatalysis is a phenomenon, in which an electron-hole pair is generated on exposure of a semiconducting material to light.

About Photocatalytic STH:

  • Photocatalytic STH (solar-to-hydrogen) is inspired by photosynthesis, where leaves use energy from incident sunlight to split water into oxygen and hydrogen.
  • The process consists of a semiconductor photocatalyst wafer immersed in freshwater or seawater.
  • When photons in sunlight strike the water, they dislodge electrons in its atoms, which trigger a redox reaction in the water and separate hydrogen and oxygen.
  • The energy source is sunlight and the feedstock is water – both abundant on Earth and green by nature.

Significance:

  • Considering electricity is the biggest component of the cost of green hydrogen, the government effectively needs cheaper renewable energy – the breakthrough could also come from cutting-edge technologies like photocatalysis.

PRACTICE QUESTION

Consider the following statements:

1. Photocatalysts are materials that change the rate of a chemical reaction on exposure to light

2. All the photocatalysts are basically semiconductors

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Answer