Single-source precursor approach for the preparation of CdS nanoparticles and their photocatalytic and intrinsic peroxidase like activity

Abstract

CdS nanoparticles (NPs) with different shapes and sizes (rods and spheres) have been synthesized through decomposition of a newly synthesized precursor complex [Cd(SOCPh)2Lut2] using structure-directing solvents such as ethylenediamine (EN), dimethylsulfoxide (DMSO) and ammonia (NH3). In addition, CdS NPs is also prepared by thermal decomposition of the precursor complex under N2 atmosphere. The precursor complex is characterized by elemental analyses, TGA, FTIR, UV–vis spectroscopy and single crystal X-ray diffraction. The distorted tetrahedron geometry of the precursor complex has been determined by X-ray diffraction, which crystallizes in monoclinic crystal system of P2(1)/n space group with a=11.0487(17)Å, b=16.396(3), c=15.413(2)Å, α=90.00°, β=109.708(4)°, γ=90.00° and Z=4. The CdS NPs are characterized using powder X-ray diffraction, transmission electron microscopy, BET analyses, UV–vis absorption and photoluminescence spectroscopy. The photo-catalytic activity of CdS NPs is studied by the degradation of Rose Bengal (RB) dye, indicating an excellent photocatalytic activity compared to that of commercial TiO2. The mechanism behind photocatalytic degradation of RB in presence of CdS NPs is elucidated using terephthalic acid photoluminescence probing technique and evidence have shown that the photogenerated holes to be the predominant active species. This paper also demonstrates the intrinsic peroxidase like activity of CdS NPs toward peroxidase substrates 3,3′,5,5′-tetramethyl benzidine (TMB) and hydrogen peroxide. Kinetic analysis indicates that the catalysis by CdS NPs show typical Michaelis–Menten kinetics. Moreover, our synthesized CdS NPs show higher catalytic performances with a higher binding affinity for the substrate TMB than horseradish peroxidase (HRP) and other recently reported nano-mimitics.