An electrochemical device including: (a) a semiconductor layer, wherein the semiconductor is silicon or silicon carbide, and where the layer has a thickness from 1 to 1000 μm; (b) a TiO2 layer on the semiconductor layer, where the layer may include an alkaline earth oxide MO up to an amount where the layer is MtiO3, and where the layer has a thickness from 5 nm to 1 mm; (c) a grid of inert metal on the TiO2 layer, arranged so as to be able to apply a electric field across the TiO2 layer; and (d) an ohmic contact on the semiconductor layer.