Charge acceptance depletion charging

Consider a photo-assisted water electrolysis cell, incorporating a photoanode and dark metal cathode. Illumination of the n-type semiconductor photoanode with a depletion space charge region results in a net flow of positive vacancies, or holes, to the semiconductor/electrolyte interface. Here the hole (h+) may be accepted by the reduced form of the oxygen redox couple. 

Since then, the depletion of ions from the air/water interface became the commonly accepted representation of the surface tension of electrolyte solutions. However, this common picture is not always true near a charged interface, there is an accumulation of counterions, predicted by the Poisson—Boltzmann treatment, which at very low electrolyte concentrations (less than 1CT3 M) can dominate the interfacial depletion of ions due to ion hydration forces,6 and consequently, the surface tension of aqueous electrolytes can decrease with increasing ionic strength (The Jones-Ray effect).7 Even more significant, the surface tension of acids decreases with increasing... 

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