Antibacterial behaviors of Cu2O particles with controllable morphologies in acrylic coatings

Enhancement of photocatalytic activity of CuO-Cu2O heterostructures through the controlled content of Cu2O

Understanding the role of nanoparticle size on energy, exergy, thermoeconomic, exergoeconomic, and sustainability analyses of an IC engine: A thermodynamic approach

In-situ microcalorimetry was used to obtain the molar surface Gibbs energy, molar surface enthalpy and molar surface entropy of Cu2O nanoparticles, and their influences of particle size and morphology were investigated. The activity and mechanism of photocatalytic degradation of methyl orange were discussed with a correlation between the Cu2O surface energy. Results indicated that the surface thermodynamic functions increased with the decrease of the particle size. The Cu2O surface energy was of the following order: spherical > octahedral > tremella-like with corresponding values of 9.826, 8.438 and 6.901 kJ mol−1, respectively. The order of catalytic activity was tremella-like > particle spherical > octahedral with a corresponding degradation rate of 94.79, 70.10 and 68.19%, respectively. The photocatalytic activity was significantly related to surface energy. Interestingly, we found that nano-Cu2O with low surface energy exhibited a high photocatalytic activity. This study provided a new understanding of the surface-activity relationship between nanomaterial surface energy and catalytic properties.

Effect of particle size and morphology on surface thermodynamics and photocatalytic thermodynamics of nano-Cu2O

The activities, selectivities, and stabilities of nanoparticles in heterogeneous reactions are size-dependent. In order to investigate the influencing laws of particle size and temperature on kinetic parameters in heterogeneous reactions, cubic nano-Cu2O particles of four different sizes in the range of 40–120 nm have been controllably synthesized. In situ microcalorimetry has been used to attain thermodynamic data on the reaction of Cu2O with aqueous HNO3 and, combined with thermodynamic principles and kinetic transition-state theory, the relevant reaction kinetic parameters have been evaluated. The size dependences of the kinetic parameters are discussed in terms of the established kinetic model and the experimental results. It was found that the reaction rate constants increased with decreasing particle size. Accordingly, the apparent activation energy, pre-exponential factor, activation enthalpy, activation entropy, and activation Gibbs energy decreased with decreasing particle size. The reaction rate constants and activation Gibbs energies increased with increasing temperature. Moreover, the logarithms of the apparent activation energies, pre-exponential factors, and rate constants were found to be linearly related to the reciprocal of particle size, consistent with the kinetic models. The influence of particle size on these reaction kinetic parameters may be explained as follows: the apparent activation energy is affected by the partial molar enthalpy, the pre-exponential factor is affected by the partial molar entropy, and the reaction rate constant is affected by the partial molar Gibbs energy.

Xuecai Tan

Papers

Effect of particle size and morphology on surface thermodynamics and photocatalytic thermodynamics of nano-Cu2O

Theoretical and experimental study on the effects of particle size and temperature on the reaction kinetics of cubic nano-Cu 2 O