<Dd> 2 H O → 2 H + O </Dd> <P> Efficient and economical photochemical water splitting would be a technological breakthrough that could underpin a hydrogen economy . A version of water splitting occurs in photosynthesis, but hydrogen is not produced . No practical version of water splitting has been demonstrated, but the two component reactions (H production and O production) are well known . The reverse of water splitting is the basis of the hydrogen fuel cell . </P> <P> Electrolysis of water is the decomposition of water (H O) into oxygen (O) and hydrogen (H) due to an electric current being passed through the water . </P> <Dl> <Dd> Atmospheric electricity utilization for the chemical reaction in which water is separated into oxygen and hydrogen . (Image via: Vion, US patent 28793 . June 1860 .) </Dd> </Dl>

Which is an example of an exothermic process splitting of water molecule