Preparation, Surface and Crystal Structure, Band Energetics, Optoelectronic, and Photocatalytic Properties of AuxCd1-xS Nanorods

A series of novel AuxCd1-xS materials (x=0, 0.01, 0.02, 0.03, 0.05, 0.07, 0.1) were prepared and their optical properties, structural-surface morphology, and photocatalytic activity for oxidation and reduction reactions under visible-light irradiation were studied. X-ray diffraction confirmed the shrinkage of the hexagonal crystal structure of CdS; the lattice parameters decreased as a=4.1904.072 angstrom and b=c=6.7906.635 angstrom with increased loading (1-10mol%) of the Au3+ dopant. Optical spectra of AuxCd1-xS revealed a significant red-shift (485538nm) of the absorption onset and band edge emission (506530nm) with notable quenching in photoluminescence. The bandgap energy decreases (2.712.41eV) with increasing Au3+ doping of the CdS nanorods along with considerable shifting of valence band (+1.13+1.04eV) and conduction band positions (-1.58-1.36eV) versus NHE. The surface area of bare CdS (90.56m(2)g(-1)) is gradually reduced to 12.32m(2)g(-1) with increasing Au3+ doping content. The photocatalytic activity considerably improves with doping, where the Au0.1Cd0.9S composite displays the highest levels of photooxidation (95%) of 0.5mM salicyldehyde and reduction of 5mMm-dinitrobenzene to m-nitroaniline (44%) and m-phenylenediamine (52%) relative to bare CdS (50%) probably due to the homogeneous dispersion of Au3+ ions throughout CdS crystal, their superior band-energetics for facile charge-separation and better photostability.