Tungsten selenide electrode

If one wants to use p-type semiconductors where the water reduction can be obtained by illumination, one suffers from the small band gaps and has to apply an auxiliary external voltage. Such systems could be used for a photoassisted electrolysis where only part of the power needed comes from the direct light absorption in the semiconductor electrode. The additional voltage could be taken from a photovoltaic cell coupled in series to the electrolysis cell. A p-type tungsten selenide electrode appears suitable for this purpose because its conduction band is located somewhat above the hydrogen potential in acidic solution. 

Energy conversion has been always a preferred application of thermoelectro-chemical methods. PECs work with semiconductor films in contact with reversible redox couples. Intense sunlight illumination generates free charge carriers and induces a cell voltage. In [172], temperature increase enhances the usable current at a tungsten selenide electrode in contact with iodinefiodide solution. 

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