Hydrothermal synthesis of Mn-doped CdS hollow sphere nanocomposites as efficient visible-light driven photocatalysts

Abstract

A series of Mn-doped CdS hollow sphere photocatalysts has been directly synthesized by a simple and facile hydrothermal route for the first time. It was demonstrated that GSH acts as the S source and a gas bubble-template in this process. The products were characterized by XRD, SEM, TEM, HRTEM, XPS, and UV-vis spectroscopy. The as-prepared CdS and Mn-doped CdS hollow spheres all showed much higher activity than P25 under visible light (λ > 420 nm) irradiation. Among them, the 2.0 mol% Mn-doped CdS sample exhibited the highest photoactivity for the removal of organic pollutant RhB, and about 99.2% MO was decomposed after 50 min of visible light irradiation. Moreover, this catalyst also showed good stability, and after four cycles, the degradation efficiency still remained at 85%. The excellent photoactivity of the as-prepared Mn-doped CdS hollow spheres could be attributed to the synergistic effects of its appropriate band-gap structure and the special porous spherical morphology. The unique hollow sphere structure may favor the harvesting of excited light due to its special multiple scattering effect within the interior space, and the doping of Mn²⁺ may facilitate the generation of photoinduced electrons and hole pairs, and inhibit their recombination rate by acting as temporary trapping sites. This material may have great application potentials in environmental remediation and energy harvesting.