Asymmetric CapMix Device Exploiting Functionalized Graphene Oxide and SPEEK Coatings for Improved Energy Harvesting From Salinity Gradients

Abstract This work investigated the possibility of using functionalized graphene oxide and sulfonated poly(ether ether ketone) coatings on activated carbons to obtain an asymmetric device suitable for Capacitive Mixing (CapMix) application. Herein the synthesis and fabrication procedures of both materials and electrodes are reported, together with a comprehensive list of electrochemical characterization techniques. The results from the electrochemical characterization are used to design the optimal operational parameters for CapMix experiments involving the materials being studied. A homemade cell is designed and fabricated for CapMix application by polymer micromachining. Electrochemical tests are conducted to optimize the process parameters and the results of this optimization are reported, proving that both the materials and the process parameters play a key role in CapMix. The final device can generate a net power output of 12 mW m⁻² by mixing simulated seawater and freshwater. This result paved the way for further application of graphene oxide in the field of renewable energy.