Unravelling mechanistic reasons for differences in performance of different Ti- and Bi-based magnetic photocatalysts in photocatalytic degradation of PPCPs

Despite numerous developments in the field of heterogeneous photocatalysis, particularly its environmental applications, there remain fundamental uncertainties regarding the key properties which primarily govern the performance of a photocatalyst. In this study, four visible-light-driven magnetic photocatalysts, viz., Ag/Fe,N-TiO2/Fe3O4@SiO2, g-C3N4/TiO2/Fe3O4@SiO2, BiOBr/Fe3O4@SiO2, and BiOBr0.9I0.1/Fe3O4@SiO2, were synthesized and comparatively studied in terms of their material characteristics, charge transfer efficiency, and photocatalytic performance in the degradation of two model pharmaceuticals and personal care products (PPCPs), ibuprofen and benzophenone-3. Amongst the tested photocatalysts, the g-C3N4/TiO2/Fe3O4@SiO2 exhibited the fastest degradation kinetics for both the PPCPs. Property-performance relationships were evaluated in which the dependence of the photocatalytic performance on various adsorption-related, electronic band-structure-related, reactive species-related, and charge carriers-related properties was examined. The strongest performance relationship was found to be with photocurrent density-an indicator of charge transfer efficiency-for both PPCPs, indicating its influential role in governing the photocatalytic performance. The findings unfold a potential research direction towards exploration of factors which can enhance the charge transfer efficiency, thereby possibly enabling the rational design of highly efficient photocatalysts for PPCPs removal. (C) 2019 Elsevier B.V. All rights reserved.