Lorentz force promoted charge separation in a hierarchical, bandgap tuned, and charge reversible NixMn(0.5−x)O photocatalyst for sulfamethoxazole degradation

Abstract

Here, a hierarchical NixMn(0.5−x)O catalyst that propels charge carriers to opposite interfaces of core@shell nanoparticle is reported. The opposite drift of charge carriers was achieved by tuning band edges in a multilevel catalyst by varying the molar concentration (x, 0→0.5) of precursors in a series of input injections. Preferential oxidation by holes on the surface of the catalyst was confirmed with the oxidation state transformation of metal ions (platinum and lead) deposited on the catalyst from their respective solutions. To obtain an electron rich surface, the synthesis scheme was reversed (x, 0.5→0), which yielded a catalyst with an inverse geometry and directed electron flow towards the surface. The collective impact of the Lorentz force and internal charge carrier drift contributed to excellent recombination suppression and 98% sulfamethoxazole degradation in 30 min. Finally, structural integrity and catalytic potential of the composite after repeated magnetic separation and degradation cycles was assessed to establish its practical applicability.