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Heterogeneous Water Oxidation Water oxidation is one of the half reactions of water splitting: 2H2O → O2 + 4H+ + 4e− Oxidation (generation of dioxygen) 4H+ + 4e− → 2H2Reduction (generation of dihydrogen) 2H2O → 2H2 + O2Total Reaction 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. Since hydrogen can be used as an alternative clean burning fuel, there has been a need to split water efficiently. However, there are known materials that can mediate the reduction step efficiently therefore much of the current research is aimed at the oxidation half reaction also known as the Oxygen Evolution Reaction (OER). Current research focuses on understanding the mechanism of OER and development of new materials that catalyze the process. ==Thermodynamics== Both the oxidation and reduction steps are pH dependent. Figure 1 shows the standard potentials at pH 0 (strongly acidic) as referenced to the normal hydrogen electrode (NHE). 2 half reactions (at pH = 0) Oxidation2H2O → 4H+ + 4e− + O2E° = 1.23 V vs. NHE Reduction4H+ + 4e− → 2H2E° = 0.00 V vs. NHE Overall2H2O → 2H2 + O2E°cell = 1.23 V; ΔG = -475 kJ/mol 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Heterogeneous water oxidation」の詳細全文を読む スポンサード リンク
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