Aluminium foil-assisted NaBH4 reduced TiO2 with surface defects for photocatalytic degradation of toxic fuchsin basic dye

• Published in: Applied nanoscience 2023-06, Vol.13 (6), p.3925-3944
• Main Authors: Rajaraman, T. S., Gandhi, Vimal G., Nguyen, Van-Huy, Parikh, Sachin P.
• Format: Article
• Language: English
• Subjects: Aluminum; Basic dyes; Catalytic activity; Chemistry and Materials Science; Electromagnetic absorption; Electron microscopy; Electron paramagnetic resonance; Electron spin; Electrons; Energy gap; Field emission microscopy; Field emission spectroscopy; Materials Science; Membrane Biology; Metal foils; Microscopy; Nanochemistry; Nanotechnology; Nanotechnology and Microengineering; Original Article; Photocatalysis; Photodegradation; Photoelectrons; Spectrum analysis; Spin resonance; Surface defects; Titanium dioxide; Ultraviolet reflection; X ray photoelectron spectroscopy
• ISSN: 2190-5509; 2190-5517
• DOI: 10.1007/s13204-022-02628-x

Reduced TiO 2 (titanium dioxide)/black TiO 2 has garnered tremendous attention among researchers due to its superior photocatalytic performance in many applications. Numerous synthetic routes exist in the literature for producing reduced TiO 2 of different colours. This paper has developed a simple, low-cost method to reduce pristine TiO 2 in 30 min using minimal amounts of sodium borohydride (NaBH 4 ) without the need for harsh conditions and an inert environment. Variation in reduction temperature and NaBH 4 /TiO 2 molar ratio produced coloured samples ranging from light grey to pitch black. Characterization of the samples was done through UV-DRS (ultraviolet diffused reflectance spectroscopy), XRD (X-ray diffraction), ESR (electron spin resonance), XPS (X-ray photoelectron spectroscopy), FESEM (field emission scanning electron microscopy) and TEM (transmission electron microscopy). The particle sizes of all samples were in the range of 20–50 nm. Enhanced visible light absorption, reduced bandgap values and presence of defect species (Ti 3+ and oxygen vacancies) on the surface of the samples were observed, which changed with varying reduction parameters. The optimal sample was found to be the one reduced at 350 ºC using NaBH 4 /TiO 2 molar ratio of 0.2 (R-350–0.2). This sample exhibited better photocatalytic activity than pristine TiO 2 and all reduced samples in the degradation of fuchsin basic (FB) dye solution under both sunlight and UV–visible light. The optimal sample, with intermediate defect concentration, had a reduced bandgap value of 2.87 eV as compared to 3.18 eV for pristine TiO 2 . Excess defect concentration due to a higher temperature and higher NaBH 4 dosage decreased the activity.