Ni-doped and Ni/Cr co-doped TiO2 nanotubes for enhancement of photocatalytic degradation of methylene blue

Mohamed Shaban; Ashour M Ahmed; Nora Shehata; Mohamed A Betiha; Abdelrahman M Rabie

doi:10.1016/j.jcis.2019.07.070

Ni-doped and Ni/Cr co-doped TiO₂ nanotubes for enhancement of photocatalytic degradation of methylene blue

J Colloid Interface Sci. 2019 Nov 1:555:31-41. doi: 10.1016/j.jcis.2019.07.070. Epub 2019 Jul 25.

Authors

Mohamed Shaban¹, Ashour M Ahmed¹, Nora Shehata¹, Mohamed A Betiha², Abdelrahman M Rabie³

Affiliations

¹ Nanophotonics and Applications Lab, Physics Department, Faculty of Science, Beni-Suef University, Beni-Suef 62514, Egypt.
² Egyptian Petroleum Research Institute (EPRI), Cairo 11727, Egypt.
³ Egyptian Petroleum Research Institute (EPRI), Cairo 11727, Egypt. Electronic address: abdo3040@yahoo.com.

PMID: 31377646
DOI: 10.1016/j.jcis.2019.07.070

Abstract

Ni-doped and Ni/Cr co-doped TiO₂ nanotubes were successfully synthesized using a novel hydrothermal method. The surface and bulk properties of as-synthesized nanopowders were characterized using various microstructural and optical techniques. The photocatalytic ability of these nanopowders was investigated systematically for the decomposition of methylene blue dye (MB) under visible light illumination. The morphological results revealed the structural transformation of TiO₂ nanotubes to nanosheets, and further to a mixture of nanosheet/nanotube on doping with Ni and co-doping of Ni/Cr, respectively. Moreover, the Ni doping causes an optical absorption edge shifts towards lower wavelengths, while doping by Ni/Cr results to an optical absorption edge shifts towards higher wavelength in comparison to TiO₂-nanotubes. Also, Ni-doping and Ni/Cr co-doping strongly affects the Raman vibrational modes owing to the changes in interplanar distance, crystallite size, dislocation density, and crystal microstrains. Among the undoped, doped and co-doped TiO₂ nanoparticles, the 6Ni/4Cr co-doped TiO₂ exhibited a higher efficiency of 95.6% and excellent stability towards the photocatalytic degradation of MB. It is attributed to the availability of many carriers for the efficient photo-oxidation within the UV-Vis optical absorption range. Also, the photocatalytic reaction kinetics and degradation mechanism of MB were discussed.

Keywords: Mechanism of degradation; Methylene blue; NiCr/TiO(2); Photodegradation; TiO(2) nanotube.