Tailored Vapor-Phase Growth of Cu_xO–TiO₂ (x = 1, 2) Nanomaterials Decorated with Au Particles

Abstract

We report on the fabrication of Cu(x)O-TiO(2) (x = 1, 2) nanomaterials by an unprecedented vapor-phase approach. The adopted strategy involves the growth of porous Cu(x)O matrices by means of chemical vapor deposition (CVD), followed by the controlled dispersion of TiO(2) nanoparticles. The syntheses are performed on Si(100) substrates at temperatures of 400-550 °C under wet oxygen atmospheres, adopting Cu(hfa)(2)·TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N',N'-tetramethylethylenediamine) and Ti(O-(i)Pr)(2)(dpm)(2) (O-(i)Pr = isopropoxy; dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate) as copper and titanium precursors, respectively. Subsequently, finely dispersed gold nanoparticles are introduced in the as-prepared systems via radio frequency (RF)-sputtering under mild conditions. The synthesis process results in the formation of systems with chemical composition and nano-organization strongly dependent on the nature of the initial Cu(x)O matrix and on the deposited TiO(2) amount. The decoration with low-size gold clusters paves the way to the engineering of hierarchically organized nanomaterials.

Surface Decoration of ϵ‐Fe2O3 Nanorods by CuO Via a Two‐Step CVD/Sputtering Approach**

“…d‐e), its complete oxidation to CuO was unambiguously demonstrated by the following issues: i) the BE of the Cu2p 3/2 peak at 934.5 eV; ii) the presence of strong shake‐up satellites at BE ca. 9.0 eV; higher than the main spin orbit components, that are a fingerprint for the presence of Cu II , having a d 9 configuration in the ground state; iii) the value of the copper Auger parameter ( α Cu = 1851.6 eV), in line with literature data for CuO free from other copper‐containing species . As a whole, these results suggested the formation of CuO/Fe 2 O 3 composites.…”

“…Based on the above issues, the present work aims to take advantage of the use of scarcely investigated Fe 2 O 3 phases with tailored morphology/dimensionality and their surface decoration with copper oxides. In particular, attention is devoted to the vapor‐phase fabrication of ϵ ‐Fe 2 O 3 /CuO nanocomposites by a combined CVD/sputtering approach, the key advantages of which in the preparation of metal‐oxide nanocomposites have already been reported . At variance with most investigations, the adopted synthetic approach allows the direct fabrication of supported (e.g., immobilized) composite materials, a key issue for their direct technological exploitation and integration into devices such as gas sensors, Li‐ion batteries, and photoelectrochemical cells.…”

A facile strategy to fabricate plasmonic Cu modified TiO 2 nano-flower films for photocatalytic reduction of CO 2 to methanol

“…3(b) shows a representative Cu2P core level XPS spectrum with two peaks at 933.1 and 952.8 eV for Cu2p 3/2 and Cu2p 1/2 , respectively. These peaks are primarily due to metallic copper because copper in oxidation states typically exhibits two satellite or shake-up peaks [29,31,47]. In addition, the Raman signals of anatase TiO 2 were enhanced based on surface enhanced Raman scattering (SERS) from the Cu NPs (Fig.…”

“…This behavior was first observed during the photocatalytic decomposition of methylene blue over a Ag(core)/SiO 2 (shell)/TiO 2 film by Awazu et al [21]. This new phenomenon was called 'plasmonic photocatalysis', which immediately sparked research on plasmonic metal enhanced photocatalysis [22][23][24][25][26][27][28][29][30][31][32][33]. Our previous studies indicated that Ag NPs can improve the visible light activity of TiO 2 nanoparticles, nanotube arrays and nano-sheet films based on their LSPR effect [10,22,23].…”

Enhanced photoelectrochemical properties of nanocrystalline TiO2 electrode by surface sensitization with CuxO quantum dots

“…As a result, it is important to discover environmentally friendly QD materials. Recently, the development of copper oxides as both the core photocatalytic material and the photoelectrochemical material has drawn increasing amounts of attention 29–31 . Copper materials, which are multifunctional p-type semiconductors, with a band gap ranging between 1.5 and 2.4 eV 32 , are environmentally friendly and can absorb in the visible light region 33, 34 .…”