Study of the Functionalities of a Biochar Electrode Combined with a Photoelectrochemical Cell.

Biochar has been obtained by pyrolysis of spent malt rootlets under limited oxygen supply and further activated by mixing with KOH and pyrolyzed again at high temperature. The total specific surface area of such activated biochar was 1148 m 2 g -1 , while that of micropores was 690 m 2 g -1 . This biochar was used to make a functional electrode by deposition on carbon cloth and was combined with a photoelectrochemical cell. The biochar electrode functioned as a supercapacitor in combination with the electrolyte of the cell, reaching a specific capacity of 98 Fg -1 , and it was capable of storing charges generated by the cell, proving current flow both under illumination and in the dark. The same electrode could be used as an air-cathode providing oxygen reduction functionality and thus demonstrating interesting electrocatalyst properties.