Manganese and Nitrogen co-doped TiO₂ for the photocatalytic degradation of anionic dyes and phenol under sunlight

ABSTRACT

Different compositions of manganese (x = 1 & 3 wt. %) and nitrogen (y = 1 wt. %) co-doped TiO₂ (Mn_xN_yT) photocatalysts are prepared by the conventional sol-gel method. The crystallinity, optical properties, phase purity and surface morphology of prepared nano-photocatalysts were characterised in detail. The structural analyses show that the simultaneous doping with manganese and nitrogen controls the growth of TiO₂ crystal structure having an average crystallite size in the range of 14.6 to 24.5 nm. The optical analysis also demonstrated that due to the synergistic effect of Mn and N, co-doped TiO₂ represents the red-shift in the absorption band edge from 3.33 eV to 2.39 eV, which improved the response of TiO₂ structure towards the visible region and enhanced electron-hole separation. Among all, Mn₃N₁T represented the better photocatalytic efficiency against anionic dyes (Blue KBR and Red GD) and phenol under optimised conditions (such as initial substrate’s concentration = 20 ppm, photocatalyst dose = 0.5 g and solution pH of 3 and 7, respectively) due to its low bandgap, low crystallite size and high absorptivity towards the visible region. The kinetics study also showed that the degradation of dyes and phenol over Mn₃N₁T followed pseudo-first-order kinetics.

KEYWORDS:

• Photocatalytic degradation
• TiO₂
• textile dyes
• phenol
• water purification system

Acknowledgement

The authors are grateful to all the contributors who assisted in this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

CRedit authorship contribution statement

Sabtain Haider: Data curation, methodology and writing original draft. Asima Siddiqa: Project administrator. Saima Farooq: Review and editing. Hamza Ayub: Formal analysis. Muhammad Siddiq: Supervisor and validation. Basit Ali: Formal analysis. Sara Qaisar: Validation.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/2374068X.2022.2159157