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Photocatalytic water splitting is a process that uses photocatalysis for the dissociation of water (H 2 O) into hydrogen (H 2) and oxygen (O 2). The inputs are light energy , water, and a catalyst(s). The process is inspired by Photosynthesis, which converts water and carbon dioxide
Thermodynamic potentials for the reduction of CO 2 to various products is given in the following table versus NHE at pH = 7. Single electron reduction of CO 2 to CO 2 − radical occurs at E° = −1.90 V versus NHE at pH = 7 in an aqueous solution at 25 °C under 1 atm gas pressure.
In heterogeneous catalysis the catalyst is in a different phase from the reactants. Heterogeneous photocatalysis is a discipline which includes a large variety of reactions: mild or total oxidations , dehydrogenation , hydrogen transfer, 18 O 2 – 16 O 2 and deuterium-alkane isotopic exchange, metal deposition, water detoxification, and ...
Photochemical reduction of carbon dioxide harnesses solar energy to convert CO 2 into higher-energy products. Environmental interest in producing artificial systems is motivated by recognition that CO 2 is a greenhouse gas. The process has not been commercialized.
Paul Sabatier (1854-1941) winner of the Nobel Prize in Chemistry in 1912 and discoverer of the reaction in 1897. The Sabatier reaction or Sabatier process produces methane and water from a reaction of hydrogen with carbon dioxide at elevated temperatures (optimally 300–400 °C) and pressures (perhaps 3 MPa [1]) in the presence of a nickel catalyst.
Natural gas has a high hydrogen to carbon ratio, so the water-gas shift is not needed for cobalt catalysts. Cobalt-based catalysts are more sensitive than their iron counterparts. Illustrative of real world catalyst selection, high-temperature Fischer–Tropsch (HTFT), which operates at 330–350 °C, uses an iron-based catalyst.
In carbon fixation, plants convert carbon dioxide into sugars, from which many biosynthetic pathways originate. The catalyst responsible for this conversion, RuBisCO, is the most common protein. Some anaerobic organisms employ enzymes to convert CO 2 to carbon monoxide, from which fatty acids can be made. [11]
Photoredox catalysis is a branch of photochemistry that uses single-electron transfer. Photoredox catalysts are generally drawn from three classes of materials: transition-metal complexes, organic dyes, and semiconductors .