Artificial Leaf For Clean Gas | 23 Oct 2019

Scientists have developed an 'artificial leaf' device that uses sunlight to produce a widely-used gas (syngas) currently made from fossil fuels, and could be used to create a sustainable liquid fuel alternative to petrol.

• It is a carbon-neutral device that can directly produce syngas in a sustainable and simple way from carbon dioxide and water, setting a new benchmark in the field of solar fuels.
  
  • Unlike the current industrial processes for producing syngas, the leaf does not release any additional carbon dioxide into the atmosphere.
• Syngas (Synthesis Gas) is currently made from a mixture of hydrogen and carbon monoxide, and is used to produce a range of commodities, such as fuels, pharmaceuticals, plastics and fertilisers.
  
  • The syngas is produced by gasification of a carbon containing fuel to a gaseous product that has some heating value. Some of the examples of syngas production include gasification of coal emissions, waste emissions to energy gasification, and steam reforming of coke.
  • The general raw materials used for gasification (creation of syngas) are coal, petroleum based materials (i.e. fossil fuels), or other materials that would be rejected as waste.
  • The name syngas is derived from the use as an intermediate in generating synthetic natural gas and to create ammonia or methanol. It is a gas that can be used to synthesize other chemicals, hence the name synthesis gas, which was shortened to syngas. Syngas is also an intermediate in creating synthetic petroleum to use as a lubricant or fuel.
• Rather than running on fossil fuels, the artificial leaf is powered by sunlight.
  
  • The device is inspired by photosynthesis—the natural process by which plants use the energy from sunlight to turn carbon dioxide into food.
  • On the artificial leaf, two light absorbers, similar to the molecules in plants that harvest sunlight, are combined with a catalyst made from the naturally abundant element cobalt.
  • When the device is immersed in water, one light absorber uses the catalyst to produce oxygen.
  • The other carries out the chemical reaction that reduces carbon dioxide and water into carbon monoxide and hydrogen, forming the syngas mixture.
  • The researchers discovered that the light absorbers work even under the low levels of sunlight on a rainy or overcast day. This means that the technology can be used anywhere in the world.

Source: ToI