After printing, the structures are pyrolyzed at 915 °C and activated for 45 min with CO2 to ensure the formation of defined, accessible ultramicropores in the Cmicro electrode. The carbon electrodes are then contacted with silver (Ag) ink and sealed inside a 3D-printed electrolyte confinement made from polypropylene (PP). Lastly the structure is filled with the liquid electrolyte (1 M TBABF4 in ACN) and equipped with an Ag-wire as pseudo-reference (Figure ). For all electrochemical measurements the device is connected in a CE to ground setup (detailed connection description in Experimental section, Figure ) synchronizing two channels with one CE using a computer-controlled multichannel potentiostat (VMP3; BioLogic ® ). Using this setup two voltages are applied separately on two channels: the voltage at the W-Cap and Ubias between GE and CE (Figure ). By implementing a reference (Agwire) the potential distributions between WE, CE, and GE can be simultaneously monitored.