Janus Electrochemistry: Asymmetric Functionalization in One Step.

Janus structures represent an overwhelming member of materials with adaptable chemical and physical properties. Development of new synthesis routes has allowed the fabrication of Janus architectures with specific characteristics depending on the final applications. In the case of the membranes, the improvement of wet routes has been limited to the capillary effect, in which the solution can gradually penetrate through the membrane, avoiding a double modification different at each face of the membrane. In this work, we propose a new electrochemical methodology to circumvent the capillary limitation and obtain a double electrochemical functionalization in only one step in a controlled way. This innovative methodology has been validated using a tridirectional spectroelectrochemistry setup. Moreover, the information provided by this optical arrangement should be especially useful for the study of the different processes (ion transfer, assisted ion transfer, and electron transfer) that can take place at liquid/liquid interfaces. Janus electrochemistry allows us to modify the two faces of a free-standing single-walled carbon nanotube electrode in a single experiment. As proof of concept, the free-standing films have been functionalized with two different conducting polymers, polyaniline and poly(3-hexylthiophene), in one electrochemical experiment. According to the obtained results, this new electrochemical methodology will open new gates for the design and functionalization of Janus materials.