Bipolar electrochemistry-A wireless approach for electrode reactions

Bipolar electrochemistry involving two feeder electrodes and a conducting object (the bipolar electrode) in an electrolytic solution has attracted a renewed interest in the last two decades due to its use within several fields ranging from materials science to sensing and beyond. The potential difference between the electrolyte and the bipolar electrode may drive oppositely directed faradaic reactions (reduction/oxidation) at the cathodic and anodic sides of the bipolar electrode. The potential difference between the solution and the bipolar electrode is highest at the extremities, which means that the potential difference for driving the faradaic processes is always largest here. This wireless technique generates an asymmetric reactivity at the surface of a conducting object allowing for modification of more delicate materials such as graphene or for simultaneous modification of an array of electrodes. In this review, the recent applications of bipolar electrochemistry are presented focusing on sensing, electrografting, electrodeposition, and the use of graphene as a bipolar electrode.