Photocatalytic water splitting

Photocatalytic water splitting is an artificial photosynthesis process with photocatalysis in a photoelectrochemical cell used for the dissociation of water into hydrogen and oxygen , using artificial, natural light.Hydrogen fuel production has most attention when  the  global warming has grown. Methods such as photocatalytic water splitting are being investigated to produce hydrogen, a clean-burning fuel. Water splitting holds particular promise since it utilizes water, an inexpensive renewable resource.

 Photocatalytic water splitting has the simplicity of using a catalyst and sunlight to produce hydrogen out of water.

When H2O is split into O2 and H2, the ratio of its products is 2:1.

 The process of water-splitting is a highly endothermic process . Water splitting occurs naturally in photosynthesis when the energy of a photon is absorbed and converted into the chemical energy through a complex biological pathway .Theoretically, infrared light has enough energy to split water into hydrogen and oxygen; however, this reaction is very slow because the wavelength is greater than 750 nm. The potential must be less than 3.0 V to make efficient use of the energy present across the full spectrum of sunlight. Water splitting can transfer charges, but not be able to avoid corrosion for long term stability.Due to the transparency of water to visible light, photolysis can only occur with a radiation wavelength of 180 nm or shorter.Materials used in photocatalytic water splitting fulfill the band requirements outlined previously and typically have dopants and/or co-catalysts added to optimize their performance.Most semiconductors with suitable band structures to split water absorb mostly UV light; in order to absorb visible light, it is necessary to narrow the band gap.

Reference: https://en.wikipedia.org/wiki/Photocatalytic_water_splitting#Method_of_evaluation