RuO₂ Nanowires and RuO₂/TiO₂ Core/Shell Nanowires: From Synthesis to Mechanical, Optical, Electrical, and Photoconductive Properties

Abstract

Functional 1D metal oxides have attracted much attention because of their unique applications in electronic, optoelectronic, and spintronic devices.[1] For semiconducting oxide nanowires (NWs) (e.g., ZnO, In 2 O 3 , and SnO 2 NWs), field-effect transistors and light-emitting diodes have been demonstrated. [2] Metallic oxide nanoscale materials, such as nanoscale RuO 2 , can be good candidates as interconnects in electronic applications.[3] RuO 2 nanomaterials have been produced by chemical vapor deposition (CVD) and through chemical reaction. [3b,4] Recently, RuO 2 NWs have been synthesized using pure Ru as metal target under different flux ratios of O 2 /Ar in a reactive sputtering system.[5]For core/shell structures, extensive research has been carried out on systems such as Ge/Si, [6] GaN/AlN/AlGaN, [7] Ta 2 O 5 /SiO 2 , [8] and Fe 3 O 4 /MgO. [9] The Ge/Si core/shell NW, for example, is a high-performance field-effect transistor because of the reduced carrier scattering. GaN/AlN/AlGaN core/shell NWs exhibit a high electron mobility. For the SiO 2 / Ta 2 O 5 core/shell structure, the axial confinement of light propagation can effectively reduce the energy loss owing to the difference in refractive index between Ta 2 O 5 and SiO 2 . Following the successful synthesis of a RuO 2 /TiO 2 core/ shell structure by reactive sputtering, [10] we mainly focus on the investigation of the physical properties of the RuO 2 NWs in the present study. The detailed epitaxial relationship and electronic structures of the RuO 2 /TiO 2 core/shell structure synthesized by reactive sputtering are investigated. The mechanical, optical, and electrical properties and photocatalyst response to UV irradiation are characterized. Our results suggest the potential application of the NWs as interconnects and optoelectronic devices. Figure 1a shows a scanning electron microscopy (SEM) image of RuO 2 NWs synthesized by the reactive sputtering approach at a synthesis temperature of 450°C for 3 h, and indicates a high density of uniform RuO 2 NWs more than several micrometers long. In addition, most of the RuO 2 NWs have a square cross section, as shown in the inset of Figure 1a. The corresponding X-ray diffraction (XRD) spectrum, shown in Figure 1b, confirms that the phase of the NWs is rutile-structured RuO 2 with lattice-constant values of a = 0.45 nm and c = 0.31 nm. After deposition of a thin TiO 2 layer via reactive sputtering deposition, the morphology of these NWs remains unchanged, but the sizes increase, as shown in Figure 1c. The corresponding XRD spectrum of the NWs is shown in Figure

Visible Light-Driven H2 Production over Highly Dispersed Ruthenia on Rutile TiO2 Nanorods

“…Similar behavior was studied by our group and other groups. 12,13,23,36 We have observed in previous fundamental studies 23 We carried out DFT studies to understand the electronic band structure of the heterojunction nanocomposites which strongly affects the photocatalytic water splitting performance. In Figure 5A, we show the density of states (DOS) of the full-relaxed (3x6)…”

“…6,5 Coupling rutile TiO2 with RuO2 has been widely studied in numerous catalytic reactions due to their lattice matching and strong metal-support interaction. [12][13][14][15][16][17] claimed that RuO2/rutile-TiO2 catalyst exhibited high catalytic activity and thermal stability toward HCl oxidation to Cl2 due to highly dispersed, ultrafine RuO2 crystallites, approximately a single unit-cell thickness, that cover the surface of TiO2 primary particle with strong interaction between RuO2 and TiO2. Xiang et al 15 demonstrated that the redistribution or spreading of RuO2 occurred from a spherical shape (~ sub 2 nm) to epitaxial island layers along the TiO2 surfaces during the chlorination reaction, forming a unique heterostructure at the interface.…”

Metal Oxide Nanoparticles

“…In contrast, RuO 2 /TiO 2 core-shell nanowires were prepared by first growing RuO 2 nanowires by reactive sputtering, followed by sputtering of the TiO 2 layer onto the surface of the RuO 2 nanowire. [78] 1.4 CHARACTERISATION…”

Synthesis of TiO2-doped SiO2 composite films and its applications

“…The photocatalytic degradation of various toxic compounds in aqueous solutions using fine titanium oxide particles has been studied by many researchers (Kudo and Kudo 2006;Tran and Nosaka 2006;Chueh and Hsieh 2007;Ghicov and Schmidt 2007;Hu and Dai 2007;Macak and Zlamal 2007;Meng and Hao 2007;Wang and Ma 2007;Weiher and Beesley 2007;Yu and Yu 2007). However, to avoid the filtration and suspension of small particle photocatalysts, the composite supports containing titania with silica, alumina or other metal oxides have been proposed (Alexeev and Chin 2005;Chu and Inoue 2005;Feng and Miedaner 2005;Yang and Zeng 2005;Li and Wu 2006;Zhang and Zhou 2006).…”