Methanol sensor for integration with GaP nanowire photocathode

We proposed a new type of the methanol concentration sensor that may be integrated directly to the GaP nanostructured photocathode. Necessary attribute for this design is the possibility to make it compatible with p-type of semiconductor. This condition follows from the fact that photocathodes for the CO2 splitting are exclusively prepared from p-type of semiconductors. Design of methanol sensor emanates from this principle. On the GaP substrate is deposited thin Pt supporting layer (100-200 nm thick).This layer is covered by 500 nm thick Nafion membrane that serves as proton filter. On the top of Nafion layer is deposited top Pt contact layer covered by thin nanostructured Pt layer layer with various thickness (0.5 -5 nm). This nanostructured Pt is formed into small islands. It serves as an absorption layer for methanol. Sensor detection properties were estimated from monitoring of I-V characteristics. They were measured in dark and under various methanol concentrations. Dark current values are in order 10-9 A, and this current increases up to order of microamps for methanol of concentration more than 95%.These measurements proved high sensitivity of the GaP compatible sensor structure. Methanol sensors were realized in form of narrow stripe on the side of the photocathode.