An Overview: Recent Development of Titanium Oxide Nanotubes as Photocatalyst for Dye Degradation

Table 4

Summary of the works reported on the different cationic-loaded TiO₂ photocatalyst.

Cationic	Author (year)	Findings	Reference
Cu	Li et al. (2008)	Cu ions on TiO2 nanotubes effectively acted as electron trappers prohibiting the recombination of photoexcited electrons and holes in Cu-loaded TiO2 nanotubes, hence improving the photocatalytic degradation of Rhodamine B under UV light irradiation within 50 min. The catalytic performance is also better than the undoped TiO2 nanotubes.	[110]
Pd	Mohapatra et al. (2008)	Self-organized TiO2 nanotubes with Pd nanoparticles were found to be an excellent photocatalyst that can decompose nonbiodegradable azo dyes (methyl red and methyl orange) due to the fact that lifetime of the charge carriers has been increased significantly	[111]
Ru	Khan et al. (2009)	Doping of Ru by the ion exchange method to the hydrothermally synthesized TiO2 nanotube was found to be an effective photocatalyst active under visible light for degradation of methylene blue dye	[112]
Fe	Deng et al. (2009)	The methyl orange was completely degraded using 0.5% Fe-doped TiO2 nanotubes under UV light irradiation within 3 h	[113]
Nd	Xu et al. (2009)	Nd-doped TiO2 nanotubes showed a high photocatalytic activity by degrading 99.6% of methyl orange within 20 min under UV irradiation	[114]
W	Xiao et al. (2009)	5 wt% of W-loaded TiO2 nanotubes enhanced photocatalytic activity of RhB degradation compared to the pure TiO2 nanotubes due to the better charge separation efficiency and the extension of the wavelength range of photoexcitation	[115]
Co	Hsieh et al. (2009)	Codoped TiO2 nanotubes showed a promising candidate in a photocatalysis degradation of basic Violet 10 Dye under visible light irradiation	[116]
W	Paramasivam et al. (2010)	The improvement of the photocatalytic degradation of Rhodamine B was observed for the addition of low WO3 content (0.2 at.% W) to the Ti nanotubes	[59]
W	Sajjad et al., (2010)	4% WOx-TiO2 nanotubes composite demonstrated the best reactivity under visible light in degradation of acid Orange 7 Dye	[117]
La	Wu et al. (2010)	La-doped TiO2 nanotubes have been tested by using methyl orange dye under UV light irradiation.	[118]
Cu	Ma et al. (2010)	Cu-doped TiO2 nanotube has been employed to degrade methyl orange. However, only 21% of methyl orange was removed using Cu-doped TiO2 nanotube arrays after 240 min of UV illumination	[119]
W	Das et al. (2011)	The high efficiency of photodegradation of Rhodamine B is observed for the 0.2 at.% W content	[120]
Pt	Su and Deng (2011)	The Pt-doped TiO2 nanotubes possess high photocatalytic activity for degrading methyl orange under UV and visible light irradiation	[121]
Fe	Pang and Abdullah (2012)	The Fe-doped TiO2 nanotubes were evaluated based on oxidation of Rhodamine B under ultrasonic irradiation	[122]
Fe	Wu et al. (2012)	The incorporation of Fe into TiO2 nanotubes has increase the efficiency of methylene blue degradation under visible light region	[123]
Cu	Sreekantan et al. (2014)	Cu loaded on TiO2 nanotube arrays demonstrates the highest photocatalytic activity with 84% degradation of methyl orange under visible light	[124]
Bi	Natarajan et al. (2013)	Bismuth-doped TiO2 nanotubes were successfully synthesized and capable of degrading Rhodamine B completely under direct sunlight	[125]