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Oxygen evolution is the chemical process of generating elemental diatomic oxygen (O 2) by a chemical reaction, usually from water, the most abundant oxide compound in the universe. Oxygen evolution on Earth is effected by biotic oxygenic photosynthesis , photodissociation , hydroelectrolysis , and thermal decomposition of various oxides and ...
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.
X-ray crystal structure of the Mn 4 O 5 Ca core of the oxygen evolving complex of Photosystem II at a resolution of 1.9 Å. [2] 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]
A simplified model of a chemical reaction with pathways for a light isotope (H) and heavy isotope (D) of hydrogen. The same principle applies for the light isotope 12 C and heavy isotope 13 C of carbon. The positions on the energy wells are based on the quantum harmonic oscillator. Note the lower energy state of the heavier isotope and the ...
Of the two half reactions, the oxidation step is the most demanding because it requires the coupling of 4 electron and proton transfers and the formation of an oxygen-oxygen bond. This process occurs naturally in plants photosystem II to provide protons and electrons for the photosynthesis process and release oxygen to the atmosphere, [ 1 ] as ...
The evolution of oxygenic photosynthesis in the atmosphere amplified the productivity of the biosphere, increasing biodiversity. [7] With the presence of photosynthesis providing oxygen to the atmosphere, respiration soon evolved to provide the necessary components photosynthesis demanded to function.
Under low oxygen concentrations and before the evolution of nitrogen fixation, biologically-available nitrogen compounds were in limited supply, [16] and periodic "nitrogen crises" could render the ocean inhospitable to life. [9] Significant concentrations of oxygen were just one of the prerequisites for the evolution of complex life. [9]
Oxygenic photosynthesis uses water as an electron donor, which is oxidized to molecular oxygen (O 2) in the photosynthetic reaction center. The biochemical capacity for oxygenic photosynthesis evolved in a common ancestor of extant cyanobacteria. [11] The first appearance of free oxygen in the atmosphere is sometimes referred to as the oxygen ...