Improving visible light photocatalytic inactivation of E. coli by inducing highly efficient radical pathways through peroxymonosulfate activation using 3-D, surface-enhanced, reduced graphene oxide (rGO) aerogels

In this work, we synthesized highly porous reduced graphene oxide foams, presenting augmented antibacterial activity in presence/absence of peroxymonosulfate (PMS). To date, this is the first investigation of photocatalytic PMS disinfection by 3D-rGO materials. The foams were prepared through hydrothermal (3DG-W) and solvothermal method (3DG-EG), and analyzed by SEM, PXRD, FTIR, Raman spectroscopy and BET. Hydrothermally synthesized aerogels (3DG-W) were better organized and had higher specific surface area. The higher ratio of I-D/I-G in 3DG-W showed the greater removal of oxygen functional groups, larger density of structural defects and a smaller average size of the sp(2) domains. Although in the dark PMS activation by 3DG and the subsequent bacterial inactivation likely proceeds via a non-radical pathway, under visible light, the bacterial inactivation rate for 3DG-W was similar to 3 times higher than that of 3DG-EG and radical pathways are dominant. The generated germicidal reactive species were identified using appropriate scavengers and accordingly, an overview of the occurring photocatalytic and PMS activation pathways is discussed, while the mechanisms leading to bacterial inactivation are hereby detailed.