Existence regions of spatiotemporal patterns in the electro-oxidation of formic acid

Experimental observations of different spatiotemporal patterns of the interfacial potential on a bismuth modified platinum ring working electrode (WE) with different positions of the reference electrode (RE) in the electrocatalytic oxidation of formic acid are presented. For small distances between WE and RE, inhomogeneous patterns (e.g., standing waves and rotating pulses) are obtained, while synchronized oscillations (i.e., in-phase active or passive oscillations of interfacial potential) take over at larger distances between WE and RE. The results can be rationalized in terms of the geometry dependence of the non-local migration coupling