Photocatalytic hydrogen production with reduced graphene oxide (RGO)-CdZnS nano-composites synthesized by solvothermal decomposition of dimethyl sulfoxide as the sulfur source

Abstract

In order to increase photocatalytic activity, to control particle size and to diminish photo-corrosion of CdZnS based photocatalysts, different compositions of Cd(1-x)ZnxSphotocatalysts were decorated on the reduced graphene oxide (RGO). The target photocatalytic composite structures (RGO-Cd(1-x)ZnxS) were firstly prepared by a solvothermal method using dimethyl sulfoxide (DMSO) as the solvent and sulfur source. RGO-Cd(1-x)ZnxSnanocomposites were characterized by the x-ray diffraction (XRD), the transmission electron microscopy (TEM), the scanning electron microscopy (SEM), ultraviolet-visible (UV–vis) diffuse reflectance spectra (DRS), photoluminescence (PL) spectra, The transient photocurrent responses, and the energy-dispersive X-ray spectrometry (EDS).Purity, the particle size of 40 nm, the crystallite sizes between 20.8 and 19.1 Å and cubic structure of the photocatalysts could be easily achieved by controlled thermal decomposition of DMSO. Decorating the photocatalysts on RGO structure prevented aggregation of Cd(1-x)ZnxS particles, enhanced transfer of photogenerated charge carriers, and increased the electron transfer rate of the photocatalysts, which provided a better photocatalytic activity. Moreover, loading photo-reduced platinum (Pt) nanoparticles on the RGO-Cd(1-x)ZnxSnanocomposite showed a significant increase in hydrogen evolution rate. Among the photocatalysts employed herein, RGO-Cd0.6Zn0.4S-Pt (5%) structure showed the highest activity with 184 μmol h−1 hydrogen evolution rate and 24.1% apparent quantum efficiency. Presences of RGO in the nanocomposite structure and synthesizing it with solvothermal method by using DMSO apparently increased the stability and activity of the nanocomposites.