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Inorganic Materials as Catalysts for Photochemical Splitting of Water Frank E. Osterloh Chem. Mater., 2008, 20 1,

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Inorganic Materials as Catalysts for Photochemical Splitting of Water Frank E. Osterloh Chem. Mater., 2008, 20 1,

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    5. Current Status 1000W/m2 solar energy available Photovoltic and electrochemical solar cells 55-77% efficiency possible but cost of production is high H2O H2 +1/2O2 ?H +237 kJ/mol, (1.3 eV/e; ?min =1100nm) Current record holders (La/KTaO3 56% UV; ZnS 90%, >300nm,Cr/Rh Modified GaN/ZnO, 2.5%,Visible No material with 10% and visible light

    6. Flat band potential must exceed reduction potential of 0.0 V at pH=0; -0.41V at pH =7) ( bottom of conduction band) +1.23 V ( at pH =0, +0.82 at pH=7) Flat band potential values are varying Evaluate Vfb = E0 – ? +1/2EG(E0 = +4.44 eV is the energy of free electron on the hydrogen redox scale) QE 2[H2]/I; I photon flux mols/s; ferrioxalate actinometry

    31. The value of the band gap only indicates the thermodynamic driving force available. This does not reflect on the kinetics of the decomposition. It can be generally concluded if the top and bottom of valence and conduction bands are positioned to promote the water splitting reaction then increase of the band gap value will indicate increased driving force for the promotion of the water splitting reaction. It can be stated the larger the band gap and if the photon absorption index and available photons were constant then the large band gap materials will favour the reaction more than the less band gap materials.

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