Effect of different silver and bromine sources in AgBr synthesis: characterization and photocatalytic properties

To understand the influence of precursors on the physicochemical and photocatalytic properties of silver bromide, AgBr photocatalysts were synthesized by a simple precipitation method using different silver (AgNO₃, Ag(NH₃)₂⁺) and bromine (KBr, CTAB) sources. Samples were characterized and tested against rhodamine B (RhB), methyl orange (MO), and paracetamol (PCT). Depending on the precursor used, differences in morphology, particle size and surface composition were observed, obtaining single AgBr, Ag/AgBr, and AgBr/CTAB materials. From these materials, single AgBr and Ag/AgBr photocatalysts obtained the highest conversion percentages for RhB and PCT, while the AgBr/CTAB photocatalysts have a restricted photoactivity with the evaluated substrates, since the CTAB molecules have a strong interaction with MO and compete with the substrates to react with the reactive oxygen species (ROS) generated by the photocatalysts. Recycling tests suggest that all samples suffer photocorrosion, decreasing their photocatalytic capacity and forming depots of metallic silver on their surfaces. Overall, these findings demonstrate that the selection of silver and bromine sources during AgBr synthesis strongly determines the morphological, surface, and photocatalytic properties of the semiconductor, providing insights into the rational design of silver halide-based photocatalysts for environmental remediation.