Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (11): 2678-2684.doi: 10.3866/PKU.WHXB201608084

• ARTICLE • Previous Articles     Next Articles

Effects of Particle Size and Temperature on Surface Thermodynamic Functions of Cubic Nano-Cu2O

Huan-Feng TANG1,Zai-Yin HUANG1,2,*(),Ming XIAO1   

  1. 1 College of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning 530006, P. R. China
    2 Guangxi Colleges and Universities Key Laboratory of Food Safety and Pharmaceutical Analytical Chemistry, Nanning 530006, P. R. China
  • Received:2016-07-14 Published:2016-11-08
  • Contact: Zai-Yin HUANG E-mail:huangzaiyin@163.com
  • Supported by:
    the National Natural Science Foundation of China(21273050);the National Natural Science Foundation of China(21573048)

Abstract:

Cubic nano-cuprous oxides, with four types of particle sizes ranging from 40 to 120 nm, were synthesized via a liquid-phase reduction method. The composition, morphology and structure of the nano-Cu2O particles were characterized by X-ray diffractometry (XRD), Raman microscopy and field emission scanning electronic microscopy (FE-SEM). In-situ microcalorimetry was used to obtain thermodynamic information about the reaction between HNO3 and bulk Cu2O or nano-Cu2O. The surface thermodynamic functions of cubic nano-Cu2O were calculated by a combination of thermodynamic principle and kinetic transition state theory. We develop a thermodynamic model for the cubic nanoparticles based on the thermodynamic model of spherical nanoparticles without bore developed by XUE Yong-Qiang et al. The particle size and temperature effects of surface thermodynamic functions are discussed by comparing the theoretical model with the experimental results. The molar surface Gibbs free energy, molar surface enthalpy and molar surface entropy increased with decreasing particle sizes. Linear trends were found between the reciprocal of particle size and surface thermodynamic functions, which agreed well with the theoretical model for a cube. The molar surface enthalpy and molar surface entropy were increased with rising temperature, whereas the molar surface Gibbs free energy decreased. This work not only enriches and develops the basic theory of nano-thermodynamics, but also provides a novel method and idea for investigating surface thermodynamic functions of nanomaterials and their applications.

Key words: Surface thermodynamic function, In-situ microcalorimetry, Thermodynamic model, Particle size effect, Temperature effect, Cubic nano-cuprous oxide

MSC2000: 

  • O642