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.

Automated summary

Biochar was obtained from spent malt rootlets through pyrolysis under limited oxygen supply and further activated by mixing with KOH and pyrolyzing again at high temperature. The activated biochar showed a total specific surface area of 1148 m(2) g(-1) and a micropore specific surface area of 690 m(2) g(-1). When used as an electrode in combination with a photoelectrochemical cell, the biochar electrode acted as a supercapacitor with a specific capacity of 98 Fg(-1), capable of storing and utilizing charges generated by the cell under both illuminated and dark conditions. Additionally, the same electrode exhibited electrocatalyst properties as an air-cathode, enabling oxygen reduction.