Cupric oxide (CuO) is a highly useful material with many applications, including firework propellants and chemically reactive materials. It is also a potential candidate for water treatment because of its low cost and abundance.

CuO is a promising material for gas sensors because of its surface conductivity and high sensitivity. This property is enhanced if the material is made into nanostructures, as shown by a variety of studies. The shape of the nanostructures is also a critical factor that affects the sensing properties.

Several groups have attempted to stabilize CuO in the liquid phase using electrostatics and various surfactants to provide steric repulsion, as well as to block the aggregation of particles. The polar head of the surfactants is absorbed on to the surface of the nanoparticles, while the hydrophobic tail provides a steric barrier that prevents the agglomeration of the particles.

We have used an e-beam deposition process to deposit 5 nm of copper on CuO at 10 degC in order to assess the influence of this deposited metal on the structure of CuO. We also examined the reactivity of these materials by means of in situ LEIS spectroscopy after deposition at varying temperatures.

The LEIS spectra obtained after deposition of 5 nm Cu on the surface of the CuO sample showed a strong Cu signal with a weak O signal. The spectra also showed an increasing Cu:O ratio after deposition, which is indicative of the transition from the solid to the melting state. The spectra were then annealed up to 200 degC.