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Water splitting is the chemical reaction in which water is broken down into oxygen and hydrogen: [1] 2 H 2 O → 2 H 2 + O 2 Efficient and economical water splitting would be a technological breakthrough that could underpin a hydrogen economy .
The oxygen-evolving complex (OEC), also known as the water-splitting complex, is a water-oxidizing enzyme involved in the photo-oxidation of water during the light reactions of photosynthesis. [3] OEC is surrounded by 4 core proteins of photosystem II at the membrane-lumen interface.
Photosynthetic water splitting (or oxygen evolution) is one of the most important reactions on the planet, since it is the source of nearly all the atmosphere's oxygen. Moreover, artificial photosynthetic water-splitting may contribute to the effective use of sunlight as an alternative energy-source.
The high-energy oxidized tyrosine gives off its energy and returns to the ground state by taking up a proton and removing an electron from the oxygen-evolving complex and ultimately from water. [4] Kok's S-state diagram shows the reactions of water splitting in the oxygen-evolving complex.
This occurs by oxidation of water in the case of oxygenic photosynthesis. The electron-deficient reaction center of photosystem II (P680*) is the strongest biological oxidizing agent yet discovered, which allows it to break apart molecules as stable as water. [4] The water-splitting reaction is catalyzed by the oxygen-evolving complex of ...
Water splitting can be done at higher pH values as well however the standard potentials will vary according to the Nernst equation and therefore shift by -59 mV for each pH unit increase. However, the total cell potential (difference between oxidation and reduction half cell potentials) will remain 1.23 V.
The semiconductor crucial to this process, absorbs sunlight, initiating electron excitation and subsequent water molecule splitting into hydrogen and oxygen. Photoanode Reaction (Oxygen Evolution): H2O → 2H++1 2O2+ 2e−. Photocathode Reaction (Hydrogen Evolution): 2H++ 2e− → H2. 41598 2017 11971
The energy of P680 + is used in two steps to split a water molecule into 2H + + 1/2 O 2 + 2e-(photolysis or light-splitting). An electron from the water molecule reduces P680 + back to P680, while the H + and oxygen are released.