Photocatalytic foams for water treatment: A systematic review and meta-analysis

Photocatalysis has proven to be highly effective for the removal of recalcitrant organic micropollutants at the lab scale. However, drawbacks such as the need for downstream removal of nanoparticle slurries and low surface areas of immobilised catalyst have, so far, hindered large-scale application. Photocatalytic foams have the potential to address these issues and advance the field towards large scale deployment. This review offers the first comprehensive overview of the state-of-the-art in this growing research field while simultaneously addressing two key issues which are slowing down further progress: The lack of classification nomenclature for foams, particularly regarding pore size and production method, and the use of kinetics as the defining feature of a photocatalyst, when alternate figures of merit, such electrical and quantum efficiencies, may be more appropriate. These were particular evident from a semi-quantitative comparison of the literature reported here, which highlighted the need for standardisation of experimental methods within the field. Finally future perspectives and best practices are discussed and recommended.