The Standard Molar Enthalpies of Formation of Nano-ZnO Particles with Different Morphologies

Abstract EN

The thermodynamic properties of nano-ZnO particles with different morphologies were studied.

First, based on the measurements of XRD and SEM, the morphologies of the five nano-ZnO products were determined as sheet, block, sieve, column, and rod, and their particle size was about 40 nm.

Then, based on a designed thermodynamic cycle, the standard molar enthalpies of formation Δ f H m Ө of the nano-ZnO particles were determined by the RD496-2000 microcalorimeter, and they are Δ f H m Ө (sheet) = ( - 337.43 ± 0.47 ) kJ · mol−1, Δ f H m Ө (block) = ( - 336.57 ± 0.43 ) kJ · mol−1, Δ f H m Ө (sieve) = ( - 337.04 ± 0.57 ) kJ · mol−1, Δ f H m Ө (column) = ( - 343.56 ± 0.39 ) kJ · mol−1, and Δ f H m Ө (rod) = ( - 341.43 ± 0.41 ) kJ · mol−1.

The results show that the bigger difference of the morphologies of nano-ZnO, the bigger difference of the standard molar enthalpies of formation.