CuxO - TiO2 composites (x=1, 2) studied by X-ray Photoelectron Spectroscopy

CuxO - TiO2 (x=1,2) nanocomposites were synthesized by an innovative Chemical Vapor Deposition (CVD) strategy, based on the initial growth of CuxO matrices (1) and on the subsequent dispersion of TiO2 nanoparticles (2). Cu(hfa)2oTMEDA (hfa=1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA=N,N,N',N'-tetramethylethylenediamine) and Ti(O-iPr)2(dpm)2 (O-iPr = isopropoxide; dpm=2,2,6,6-tetramethyl-3,5-heptanedionate) were used as copper and titanium molecular sources, respectively. The syntheses were carried out under O2+H2O atmospheres on Si(100) substrates. In step (1), pure and homogeneous single-phase Cu2O/CuO nanosystems were obtained at 400/550°C, with total pressures of 3.0/10.0 mbar, respectively. Interestingly, the obtained nanocomposites were characterized by the surface formation of Cu(I)-Cu(II) mixtures, due to the occurrence of interactions between CuxO and TiO2. This work is dedicated to the characterization of two representative samples by X-ray Photoelectron Spectroscopy (XPS), focusing in particular on the analysis on the O1s, Cu2p and Ti2p core levels.