Novel testing procedure of area-specific exchange current density for photoactive powder: Application in PEC water splitting

The study reports a novel patented test and the electrochemical cell for its implementation to estimate the area-specific exchange current density for photoactive powder. The test was employed for the photo-electrode reaction in the PEC water splitting. Testing procedure included impedance measurements and was carried out in the original three-electrode cell with an alkaline electrolyte where working Ni electrode behaves as an ideal polarized electrode and is in immediate contact with the photoactive powder additive. The application of this test is presented for the UV- and visible light photoactive TiO2-xCx:nC powder. The test of TiO2-xCx:nC powder confirmed that the polarization resistance of the designed electrochemical cell is due only to photoactive powder. The area-specific exchange current density was determined for the photo-electrode reactions on TiO2-xCx:nC powder under UV- and visible light, as well as their ratio. The obtained ratio correlates well with the previous data on the rate constants for the UV- and visible-driven photocatalytic oxidation of a model solution performed in the presence of the same powder TiO2-xCx:nC.