Fabrication of CDs/CdS-TiO ternary nano-composites for photocatalytic degradation of benzene and toluene under visible light irradiation.

An efficient cadmium sulfide quantum-dots (CdS QDs) and carbon dots (CDs) modified TiO photocatalyst (CdS/CDs-TiO) was successfully fabricated. The as-prepared ternary nano-composites simultaneously improved the photo-corrosion of CdS and amplified its photocatalytic activity. The introduction of CdS QDs and CDs could enhance more absorbance of light, prevent the undesirable electron/hole recombination, and promote charge separation, which was important for the continuous formation of OH and O radicals. When the optimal mass ratio of CdS QDs to CDs was 3:1, above 90% degradation efficiencies were achieved for benzene within 1h and toluene in 2h, while that of pure TiO (P25), CdS QDs-TiO, CDs-TiO nano-composites was around 15%. Owing to the symmetric structure and conjugation of methyl with benzene ring, the degradation of toluene was more difficult than benzene to carry on. The new fabricated nano-composites showed good prospective application of cleaning up refractory pollutants and the resource utilization.