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))Zn(x)Sphotocatalysts 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))Zn(x)Snanocomposites 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 angstrom 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))Zn(x)Snanocomposite 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 mu mol 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.