Correlation between Deposition Parameters and Hydrogen Production in CuO Nanostructured Thin Films

Abstract

In this article, we report a systematic investigation of the role of (i) substrate temperature, (ii) oxygen partial pressure, and (iii) radio frequency (rf) power on the crystal structure and morphology of CuO nanostructured thin films prepared by means of rf-magnetron sputtering starting from a Cu metal target. On selected films, photocatalytic tests have been carried out in order to correlate the structural and morphological properties of the thin films prepared under different conditions with the photocatalytic properties and to find out the key parameters to optimize the CuO nanostructured films. All of the synthesized films were single-phase CuO nanorods of variable diameter between 80 and 200 nm. Better-aligned rods were obtained at relatively low substrate temperatures and from low to intermediate oxygen partial pressures, resulting in more efficient photocatalytic activities. Our investigation suggests a relevant role of the crystallographic orientation of the CuO tenorite film on the photocatalytic activity, as demonstrated by the significant improvement in H2 evolution for highly oriented films.

Shape Evolution of Hierarchical W18O49 Nanostructures: A Systematic Investigation of the Growth Mechanism, Properties and Morphology-Dependent Photocatalytic Activities

“…So far, numerous studies related to the photocatalytic performance of oxide semiconductor have been carried out. For example, semiconductors such as TiO 2 [ 2 ], ZnO [ 3 ], CuO [ 4 ], MoO 3 [ 5 ], WO x [ 6 ], Bi 2 WO 6 [ 7 ] and g-C 3 N 4 [ 8 ] have been used as efficient photocatalysts. Among them, W 18 O 49 , which is a wide band-gap n-type semiconductor, has an unusual defect structure and intense near-infrared photoabsorption [ 9 , 10 ].…”

Nanostructured Magnéli-Phase W18O49 Thin Films for Photoelectrochemical Water Splitting

“…To date, several different semiconductor metal oxides such as ZnO, TiO 2 , CuO, Bi 2 WO 6 , and MoO 3 have been developed for water splitting [7][8][9][10][11]. Among them, tungsten oxide is one of the most common semiconductor oxides used in PEC cells due to its ability to absorb the visible light spectrum, high stability in the electrolyte solutions, and the ability to exist in various compositional forms such as WO 2 , WO 3 , and W 18 O 49 [12][13][14].…”

Supported Mn3O4 Nanosystems for Hydrogen Production through Ethanol Photoreforming

“…[10][11][12]17 Nevertheless, a major titania disadvantage is the high band-gap (E G ≈ 3.2 eV), which requires UV photon excitation, accounting for only 3-4% of the incident solar radiation. 9,12 As a consequence, great attention has been dedicated to the investigation of various metal oxide semiconductors as photocatalysts for water splitting, 6,13,[18][19][20][21][22][23][24] but the process efficiency is still far from industrial viability due to: i) the backward H 2 and O 2 reaction to yield water; ii) the recombination of photogenerated electron and holes, and iii) the need to improve photocatalyst sunlight absorption, to exploit solar illumination for real-world end-uses. [12][13]18 To overcome the first two drawbacks, photoreforming processes, based on the use of aqueous solutions containing biomass-derived oxygenates (e.g.…”

“…ethanol, glycerol,…), stand as a valuable option. 12,18,25 The use of renewable feedstocks and solar energy to produce hydrogen is a much more sustainable approach than processes based on fossil fuels reforming. 17 The main drawback is the generally low energy conversion efficiency, which can be enhanced by many possible strategies (e.g.…”