Anode Design for Electrochemical Advanced Oxidation Process: To What Extent Are Boron-Doped Diamond Paste Electrodes Suitable for the Treatment of Organics in Water?

Electrochemical oxidation process (eAOP) offers potential for a more eco-friendly and efficient alternative for the treatment of organics in water. It does not require the addition of chemicals, can tolerate turbidity, and is effective against persistent organics, but there is yet to be a suitable anode design. The current state‐of‐the‐art design uses freestanding boron‐doped diamond (BDD), selected for its high overpotential for water oxidation and high stability. On the other hand, it is not cost nor energy efficient for commercial applications yet, due to the high cost of BDD production and the limitations of its planar geometry.

To address these challenges, we have designed BDD paste electrodes (BDDPEs) with the goals of reducing the amount of BDD required per unit surface area and improving mass transport. We have created BDDPEs by mechanically grinding freestanding BDD into powder, combining it with paraffin wax at a 2:1 weight ratio, and depositing it onto a glassy carbon substrate at different loadings. These electrodes are then characterized electrochemically using cyclic voltammetry for their redox behaviour. We observed high overpotentials for water oxidation as expected; however, undesirable substrate features were present, and the electrodes have high resistance. With further investigation, we inferred that the high overpotential is likely due to the reduced electroactive area created by the wax, and that the film is too porous. While the BDDPEs we designed decrease material cost by over 95%, their electrochemical properties at this point render them unsuitable for viable water treatment applications and additional research is required.