Abstract: In order to study size dependence of the thermodynamic properties of chemical reaction, nanoparticles of diamond were simulated by use of spherical C clusters, the properties of chemical reaction of diamond nanoparticles with different sizes and O2 were calculated by quantum chemistry method. The results showed that the particle size had obvious effects on the molar standard entropy of reaction, the molar standard enthalpy of reaction, the molar standard Gibbs free energy, and the standard equilibrium constant in heterogeneous reactions; the molar standard entropy of reaction, the molar standard enthalpy of reaction, and the molar standard Gibbs free energy decreased and the standard equilibrium constant increased with the particle diameters of reactants decreasing. These regularities were consistent with experimental results.

Key words: Nanoparticles, Quantumchemistry, Particle size, Thermodynamic property, Molar standard entropy of reaction, Molar standard enthalpy of reaction, Molar standard Gibbs free energy