3D printing by direct ink writing of graphite electrodes using whey as sustainable binder

Traditionally, electrodes are produced by coating slurries of porous carbon powders on thin metallic plates. With the development of additive manufacturing technologies, new production methods have been studied in the literature that are intended to the fabrication of 3D electrodes with geometries that offer advantages in terms of easing the different transport phenomena involved in electrochemical processes. However, the low mechanical strength of the 3D electrodes hampers their applicability. This study introduces a novel method for producing graphite/graphene oxide electrodes that possess adequate flexural strength. The proposed method involves using whey, a sustainable by-product of the dairy industry, as a binder. The electrodes are made by direct ink writing (a room temperature extrusion 3D printing technique) which allows the manufacture of 3D structures by overlapping layers of material filaments. By using this technique, electrodes with geometries tailored to satisfy the specific requirements of the application can be prepared. Specifically, we have developed electrodes for water splitting with complex geometries in which the active surface area is enhanced and that guarantee a quick release of the bubbles formed in the reaction, thus avoiding the problems related to mass transport associated to conventional, flat electrodes.