Pivotal role of N and Bi doping in CQD/Mn3O4 composite structure with outstanding visible photoactivity

Abstract

Herein, the effect of N and Bi-doped carbon quantum dots (CQDs) on enhancing the photocatalytic activity of Mn₃O₄ was compared. The formation of tetragonal Mn₃O₄ nanoparticles was confirmed by XRD. SEM depicted a densely packed irregular-shaped nanoparticle matrix while HRTEM revealed fringes corresponding to the characteristic planes of the various elements present in the composites. The functional groups representing the elements present in the synthesized nanomaterials were analysed via FTIR. XPS confirmed the N and Bi doping in the synthesized CQDs composites. The UV-Vis DRS analysis showed a reduction in the bandgap energies of the composite photocatalysts. The addition of N- and Bi-doped CQDs resulted in a reduction in PL intensity. The photocatalytic performance of the developed nanocomposites was compared in the solar-driven degradation of bromophenol blue. The photocatalytic efficiency of Mn₃O₄ was greatly improved in the composites with the highest effect shown by 2.0 mL-NCQDs/Mn₃O₄. The remarkably boosted photocatalytic efficiency is ascribed to the excellent charge separation and charge transfer ability of the doped carbon quantum dots.