TiO₂ nanotubes sensitized with CdSe via RF magnetron sputtering for photoelectrochemical applications under visible light irradiation

Abstract

Highly ordered TiO2 NT arrays were easily decorated with CdSe via RF magnetron sputtering. After deposition thermal annealing at different temperatures was performed to obtain an improved TiO2/CdSe interface. The heterostructures were characterized by RBS, SEM, XRD, HRTEM, UV-Vis, EIS, IPCE and current versus voltage curves. The sensitized semiconducting electrodes display an enhanced photocurrent density of ca. 2 mA cm(-2) at 0.6 V (vs. Ag/AgCl) under visible light (λ > 400 nm). The sensitized photoelectrodes displayed 3 and 535-fold enhanced photocurrent when compared to bare TiO2 NTs under 1 sun and under visible light illumination, respectively. IES results confirmed the improved charge transfer across the TiO2/CdSe/electrolyte interface after annealing at 400 °C. Incident photon-to-electron conversion efficiency measurements confirmed the efficient sensitization by allowing photoresponse in the visible range.

Effect of anodisation time and thermal treatment temperature on the structural and photoelectrochemical properties of TiO2 nanotubes

“…The samples were annealed at 500 C for 3 hours under air. The samples were labeled as Nt 0.5 -TiO 2, Nt 2 -TiO 2, Nt 2.5 -TiO 2, Nt 5 -TiO 2 and Nt 14 -TiO 2 [9,19,20]. The sample that presented the best photoelectrochemical response, was annealed at 400 C, 500 C and 600 C for 3 hours under air.…”

“…Therefore, TiO 2 based materials have been widely applied in dye sensitised solar cells, hydrogen production, the degradation of dyes and polymers [4][5][6][7][8][9]. In porous films of nanostructured semiconductors, the electronic transport is carried out through random pathways, by hopping from one nanoparticle to another, finding several energy barriers as grain boundaries and surface states, which causes the overall system conductivity to be very slow.…”

CdS-coated TiO2nanotube layers: downscaling tube diameter towards efficient heterostructured photoelectrochemical conversion

“…Especially, self-organized TiO 2 nanotube layers possess inner and outer surfaces of tubes, which are highly beneficial as compared to nanowires 18 or nanorods. 14,15 To achieve higher power conversion efficiency levels, the surface can be, in a further step, coated by a secondary material using chemical bath deposition, 8,19 spincoating, 20,21 sputtering, 22 electrodeposition, 23 a solvothermal method, 24,25 and atomic layer deposition (ALD). 26–28 However, only the ALD technique leads to the homogeneous covering of the nanotube interiors as well as exteriors, 27,28 thus ensuring the best possible TiO 2 –chromophore interface, especially for high-aspect ratio nanotubes.…”

TiO2 Nanotube/Chalcogenide-Based Photoelectrochemical Cell: Nanotube Diameter Dependence Study

“…Unlike mesoporous TiO 2 supports, ordered nanostructures, such as high aspect ratio selforganized TiO 2 nanotube layers [8][9][10] or epitaxially grown TiO 2 nanorods 11,12 , offer the advantage of directed charge transport and controlled phase separation between donor and acceptor parts of the solar cell and thus they seem very promising for nanoscale solar hybrid technologies 9 . Recently, non-silicon solar cells based on TiO 2 nanotube layers sensitized by organic dyes 8 , perovskites 13 and chalcogenides [14][15][16][17] have been presented. The latter class of materials is comparably more stable under UV light and ambient conditions, which make these materials promising for future generation of solar cell devices.…”