Spectrally selective coatings obtained from electrophoretic deposition of CuO nanoparticles

Cathodic electrophoretic deposition (EPD) of CuO nanoparticles is investigated for the formation of CuO tandem photothermal absorber starting from CuO-isopropanol suspension. Prior to the deposition step, the stabilization of the suspension in request is achieved via the addition of Mg(NO3)2 acting as a stabilizer but, also as a binder for the final coating. The colloidal dispersion stability is studied as a function of the concentration of Mg(NO3)2 added to the suspension by dynamic light scattering coupled with laser doppler velocimetry in order to determine the size and the charge of particles respectively. EPD parameters, such as the electric field and deposition time, have been investigated in order to control the thickness and the morphology in order to select the most promising coatings. The evolution of the thickness, obtained from scanning electron microscopy images, as a function of deposition time for different applied electric field is in agreement with a linear Hamaker law type. This is also used here as a first attempt to extract the effective density of the coating. Finally, the conversion efficiency of the tandem material is calculated from the reflectance spectra of the UV-vis-NIR and the Fourier transform InfraRed spectroscopy in order to link the EPD parameters to the spectral selectivity. The optimal coating was formed with an applied electric field of 50 V·cm− 1 for a deposition time of 30 min yield the highest efficiency at 0.8.