New porous bismuth electrode material with high surface area

Bismuth electrodes are particularly interesting owing to their high hydrogen evolution overpotential and electrocatalytic activity. In this work, a novel porous bismuth electrode was prepared via an electrochemical deposition of bismuth on a porous graphite felt of high specific surface area, employing bismuth(III) oxide as reactant and a flow electrochemical cell as reactor. A solubility up to 1molL−1 of bismuth was obtained in basic medium using a suitable complexing agent. We solved the problems linked to the heterogeneous potential distribution in the 3D porous structure and to the formation of dendritic excrescences that led to mechanically fragile material by using a suitable flow electrochemical cell, a periodically changing current with short on-pulses and long off-pulses and by limiting the electrodeposition of Bi on the external surfaces of the felt due to diffusion. A Bi-modified electrode with high specific surface area and low bulk density was achieved using this method.