Water electrochemical splitting

The great natural process of photosynthesis works by means of an electrochemical step as well. In it, water is split photoelectrochemically to produce atomic H and 02, and the H produced later reacts chemically with C02 present in the air to provide food for green plants, which then enter the food chain and give back to us solar energy to power the moving parts of our bodies. 

Water electrolysis is an electrochemical reaction where water is split into hydrogen and oxygen in the presence of a catalyst and applied electric field. As current density increases the cell losses due to membrane, electrode, and interfacial resistances dominate and are referred to as ohmic overpotential. 

Solar Energy-Assisted Electrochemical Splitting of Water Kinetic, energetic, and solid-state considerations in the search for suitable electrodes for water splitting elaborated. 61... 

Under the influence of the electric held, the niunber of hydronium ions generated at the anode is the same as that of hydroxide ions generated at the cathode, so the flow of hydronium ions in one direction is in equilibrium with the flow of KOH into the other direction. Thus, the boundary layer between hydronium and potassium ions is spatially fixed. If the applied current and, consequently, the flow of hydronium ions to the cathode are changed, the flow of hydroxide ions to the anode is changed in the same way. Thus, the electrochemical split of water is the motor for this circulating pool of potassium ions. 

Many materials can be hydrided with two possible approaches, viz., the direct dissociative chemisorption of a hydrogen molecule and the electrochemical splitting of a water molecule (H2O), as described respectively by the following reactions [12] ... 

The electrochemical behavior of the C70 solvent-cast films was similar to that of the C60 films, in that four reduction waves were observed, but some significant differences were also evident. The peak splitting for the first reduction/oxidation cycle was larger, and only abont 25% of the C70 was rednced on the first cycle. The prolate spheroidal shape of C70 is manifested in the II-A isotherm of C70 monolayers. Two transitions were observed that gave limiting radii consistent with a transition upon compression from a state with the long molecnlar axes parallel to the water snrface to a state with the long molecnlar axes per-pendicnlar to the water surface. 

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