Particle Size and Temperature Effects on Surface Thermodynamic Functions and Particle Size Effects on Prescribed Thermodynamic Functions for Cadmium Sulfide Nanospheres

Spherical cadmium sulfide (CdS), with five kinds of particle size ranging from 31 nm to 117 nm were synthesized by microemulsion method. The phase composition and morphology of CdS were characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD), respectively. Based on solution thermodynamic theory, combined with thermochemical cycle theory and thermodynamic theory, the theoretical models and the relationships between molar surface thermodynamic functions and partial mole surface thermodynamic functions of spherical nanomaterials with different particle sizes were deduced and established. The law and reason of particle size and temperature effects on surface thermodynamic function for cadmium sulfide nanospheres , as well as particle size effects on the prescribed thermodynamic function, were discussed. Results show that the ratio of partial molar surface thermodynamic functions to molar surface thermodynamic functions of CdS nanospheres ( G N P s : G m s , H N P s : H m s , $G_{NP}^s:G_m^s,H_{NP}^{\text{s}}:H_m^s,$ S N P s : S m s $S_{NP}^{\text{s}}:S_m^s$ )have the value of 2:3. The reciprocal of particle size is linearly proportional to the molar surface thermodynamic functions, which agreed well with the theoretical thermodynamic models of spherical nanoparticles . With the same particle size, G m s $G_{\text{m}}^s$ , S m s $S_m^s$ and H m s $H_{\text{m}}^{\text{s}}$ all increase as temperature increases. At 298.15 K, the absolute value of Δ f G m b , θ ${\Delta }_f{G}_m^{b,\theta }$ and Δ f H m n , θ ${\Delta }_f{H}_m^{n,\theta }$ both increase while S m n , θ $S_{\text{m}}^{n,\theta }$ decreases with the particle size of CdS nanospheres increase.