Design of 3d carbon nanotube monoliths for potential-con-trolled adsorption

The design of 3D monoliths provides a promising opportunity to scale the unique properties of singular carbon nanotubes to a macroscopic level. However, the synthesis of carbon nano-tube monoliths is often characterized by complex procedures and additives impairing the later macroscopic properties. Here, we present a simple and efficient synthesis protocol leading to the for-mation of free-standing, stable, and highly conductive 3D carbon nanotube monoliths for later application in potential-controlled adsorption in aqueous systems. We synthesized monoliths display-ing high tensile strength, excellent conductivity (up to 140 S m⁻¹), and a large specific surface area (up to 177 m² g⁻¹). The resulting monoliths were studied as novel electrode materials for the reversible electrosorption of maleic acid. The process principle was investigated using chronoamperome-try and cyclic voltammetry in a two-electrode setup. A stable electrochemical behavior was ob-served, and the synthesized monoliths displayed capacitive and faradaic current responses. At moderate applied overpotentials (± 500 mV vs. open circuit potential), the monolithic electrodes showed a high loading capacity (~20 µmol g⁻¹) and reversible potential-triggered release of the an-alyte. Our results demonstrate that carbon nanotube monoliths can be used as novel electrode ma-terial to control the adsorption of small organic molecules onto charged surfaces.