Two new doping-free manufacturing processes for bread-derived carbon electrodes with control over micro- and macro-topological surface features.

Pyrolyzed carbon electrodes (PCEs) can provide sustainable alternatives in electric devices, but it is difficult to control their surface geometries during their semi-destructive fabrication procedure. Impressive contributions have been made to the field of PCE fabrication in terms of the nanoscale, functionalization, and separation applications; however, further progress towards an emphasis on a sustainable life cycle is the next step forward. Here, we propose two new methodologies for creating sustainable PCEs: stamping, where a user-designed, 3D printed electrode precursor (EP) imparts a shape on an organic material, and reconstitution, where the same EP acts as a mould as a mixture of agitated organic material and water dries to leave behind a rigid shape. Both methods allow for the reuse of the EP and the upcycling of biologically derived waste products as a pyrolytic input, and they do not require chemical modification. A comparison of the two methodologies is discussed as surface features of PCEs scale by a factor of 0.78 during the reconstitution process and by a factor of 0.68 during the stamping process. These PCEs maintain defined structures on the micro-scale and demonstrate previously unachievable resolution to the naked eye prior to these two novel pathways.