Porous PEI coating for copper ion storage and its controlled electrochemical release

The use of copper-based chemicals to prevent biological growth has been widely practiced in the past. However, leaching of the copper has increased concentrations in ports and marinas, posing a risk to marine life and the environment. It is therefore timely to develop a sustainable antibiofouling coating that could replace conventional copper-based paints. Herein, the use of cross-linked polyethylene imine (PEI) coated on conducting carbon cloth electrodes as a material that can absorb copper from seawater and allow for controlled electrochemical release of copper as a biocide to prevent biofouling is proposed. The results show that the porous coating can store and release copper ions over multiple cycles by passing only 1 mA cm⁻² current density through the electrode in artificial seawater. This could enable a closed-cycle, copper-based antifouling coating, i.e., a coating that uses the well-established biocidal activity of copper, but without any net release to the ocean.