Oxidation behavior of copper nanoparticles at low temperature

A mass gain for copper nanoparticles with a mean diameter of 20 nm in a 20% oxygen–nitrogen atmosphere was measured at 150–300 °C using thermogravimetry (TG). The mass gain equilibrium of the copper particles differed at each temperature, and a threshold temperature was recorded. Oxide products, consisting mainly of Cu2O, formed on the copper nanoparticles below the threshold temperature. Above the threshold temperature, there was an initial, and drastic, formation of Cu2O, which then changed to CuO. The activation energy for the oxidation of the copper nanoparticles that could be calculated from the rate of the mass gain was an indication of the nano-effect of the copper nanoparticles.

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► The mass gain of oxidized copper nanoparticles was measured at 150–300 °C.
► A threshold temperature for the mass gain of the copper particles was recognized.
► The threshold temperature was related to the type of oxide product.
► Activation energy in the oxidation of copper nanoparticles indicated a nano-effect.