Coupled photovoltaic-electrolysis systems

Photoelectrochemical water splitting Photocatalytic water splitting Coupled photovoltaic - electrolysis systems Thermochemical conversion Photobiological methods Molecular artificial photosynthesis Plasma-chemical conversion Mechano-catalytic, magnetolysis, radiolysis, etc. 

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. 

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