Correlation between microstructural defects and photoelectrochemical performance of 1D Ti–Nb composite oxide photoanodes for solar water splitting. (20th September 2019)

• Record Type: Journal Article
• Authors: Saleh, Aya A.; Farag, Mahmoud; Allam, Nageh K.
• Is Part Of: International journal of hydrogen energy. Volume 44:Number 45(2019)
• Page Start: 24418
• Page End: 24429
• Publication Date: 2019-09-20
• Subjects: Water splitting -- Mixed oxides -- Photoanodes -- IPCE -- Ti–Nb oxide; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2019.07.219
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: We report on the optimized fabrication of ultrathin wall nanotubes grown on Ti–Nb alloy via anodization in organic-based electrolytes. The nanotubes are vertically aligned with wall thicknesses of 5–8 nm, diameters of 180–200 nm, and lengths of 2–2.8 μm. Raman spectroscopy and glancing angle x-ray diffraction (GAXRD) measurements indicated the formation of composite oxides of anatase TiO2 and monoclinic Nb2 O5 . The composite oxides showed better stability at elevated temperatures up to 650 ᵒC and with much smaller induced microstrain compared to the TiO2 counterpart. X-ray photoelectron spectroscopy (XPS) analysis confirmed the composition of the fabricated nanotubes as a mixed TiO2 –Nb2 O5 composite. Upon their use as photoanodes to split water, the composite TiO2 –Nb2 O5 NTs showed almost 2-fold increase in the obtained photocurrent compared to that of bare TiO2 NTs prepared under the same conditions. Moreover, the incident photon to current efficiency (IPCE) of the mixed oxide nanotubes was higher than that of bare TiO2 with a positive shift towards longer wavelengths, indicating improved electron mobility and charge collection. Hence, the addition of Nb resulted in the formation of thermally stable and photoactive photoanodes for solar fuel production. Graphical abstract: Image 1 Highlights: Optimized fabrication of ultrathin wall nanotubes grown on Ti–Nb alloy. The composite oxides showed stability at elevated temperatures up to 650 °C. The photoelectrochemical performance is correlated with the microstructure. The composite TiO2 –Nb2 O5 NTs showed almost 2-fold increase in the obtained photocurrent. The IPCE of mixed oxide nanotubes was higher than that of bare TiO2 with a positive shift.