Electrochemical advanced oxidative processes (EAOP) are a promising strategy for destruction of recalcitrant organic contaminants (i.e. forever chemicals), such as per- and poly- fluoroalkyl substances (PFAS) in drinking water. The efficacy of EAOP electrodes is dictated to a great extent by their oxidative stability and electrochemical reactivity towards the generation of reactive oxygen free radical species for extracting fluorine from PFAS. These criteria are relevant for novel materials that have yet to be discovered and implemented for destruction of forever chemicals. Generating these reactive species electrochemically at electrodes provides an advantage over other direct oxidation processes that rely on chemicals or other harsh conditions. Presently, boron-doped diamond and Magnéli titanium oxide (Ti4O7) are the two most promising materials for EAOP-driven PFAS destruction. In this work, we demonstrated that niobium-doped titanium oxide (Nb-TiO2) with a Nb dopant concentration of 10%, yielded high oxidative stability and high generation of reactive oxygen free radical species. This novel use of Nb-TiO2 was motivated by density functional theory (DFT) calculations to predict the overpotential for oxygen evolution, which must be high in order to oxidize PFAS. Following this critical study, we have now focused our study on leveraging DFT calculations to further validate the efficacy of boron-doped diamond, Ti4O7, Nb-TiO2, and will leverage that garnered knowledge-base to discover additional novel materials in future studies. This computation-guided effort is then complemented by rigorous experimentation to test novel EAOP materials for their ability to destroy forever chemicals.

Density function theory–guided catalysis development for the electrochemical destruction of forever chemicals

ACS Spring 2022

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