Synthesis of graphene quantum dots doped CdS composites for photoelectric properties

Abstract

Cadmium sulfide/ graphene quantum dots (CdS/GQDs) composites were fabricated by a simple one-step solvothermal method using cadmium acetate and thiourea as precursors for Cd and S, respectively. GQDs were compounded with CdS, which resulted in a decrease in zeta potential. The lattice fringes of 0.34 nm and 0.33 nm were ascribed to the (002) direction of GQDs and CdS, respectively. The UV absorption spectrum of CdS/GQDs composites presented a red-shifted, and the photoluminescence intensity of CdS/GQDs composites declined upon the addition of GQDs. The photoelectric properties of CdS/GQDs composites were significantly stronger than those of pure CdS. The relationships between photoelectric responses and the contents of GQDs were investigated. The photocurrent density reached a maximum of 3.58×10-6A/cm2 when the content of GQDs was 0.4wt%, but the photocurrent density of pure CdS was 0.15×10-6A/cm2. The photocurrent value was 23 times higher than that of pure CdS. Meanwhile, the impedance value achieved the minimum.