Authors: Valenzuela, L; Faraldos, M; Bahamonde, A; Rosal, R

Electrochim. Acta. vol: 395. page: 0013-4686.
Date: nov-01. 2021.
Doi: 10.1016/j.electacta.2021.139203.

Microbial contamination is a challenging concern due to the health threat caused by infections. Therefore, the development of efficient antimicrobial materials and processes is a crucial need for disinfecting water and surfaces. In this study, electrospray was used to prepare composite photoanodes for photoelectrodisinfection. Titanium dioxide (TiO2) and cerium-doped titanium dioxide (Ce TiO2) composites with Graphene Oxide (GO) were electrosprayed onto graphite paper to create homogeneous coatings of uniformly distributed nanoparticle aggregates with a layer thickness of 1.0-1.5 mu m. The photoanodes were irradiated using 365 nm LED light with irradiance representing a conservative estimation of the UVA component of solar light. The external potential for electrocatalysis (dark) and photoelectrocatalysis was set at + 0.6 V. The disinfection performance was assessed using anodes pre-exposed for 20 h in the darkness to exponentially growing cultures of Staphylococcus aureus. The highest antimicrobial activity was obtained for Ce-TiO2/GO anodes, which led to a 3-log reduction (99.9%) in the number of culturable cells after only 24 min of irradiation. The highest current density was also obtained for the same material and attributed to a better separation of charge carriers. Cell impairment was attributed to the overproduction of intracellular reactive oxygen species (ROS), which was higher in photoelectrocatalysis than in photocatalysis and electrocatalysis, with anodes performing in the following order: Ce-TiO2/GO > Ce-TiO2 > TiO2/GO > TiO2. The photoanodes exhibited steady photocurrent response, good photostability, and could be kept essentially clean from biofilms and colonizing bacteria. (C) 2021 Elsevier Ltd. All rights reserved..