Effect of La-doping on NiO photocatalyst for enhancing photocatalytic degradation performance under visible light irradiation: DFT calculations and degradation mechanism

• Published in: Inorganic chemistry communications 2023-10, Vol.156, p.111172, Article 111172
• Main Authors: Aejitha, S., Dhanraj, G., Govindaraj, T., Senthil kumar, N., Maiz, F., Shkir, Mohd, Kim, Woo Kyoung, Reddy Minnam Reddy, Vasudeva, Kim, Dong Hyo
• Format: Article
• Language: English
• Subjects: Coprecipitation; La-doped NiO; MB dye; Photocatalysis; Visible light irradiation
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2023.111172

[Display omitted] •Novel La-doped NiO nanoparticles were synthesized by a simple Co-precipitation method.•3% La-NiO possessed highest specific surface area of about 72.82 m2/g.•The La-dopant can promote the photogenerated charge carriers' separation efficiency.••OH and •O2– play a dominant role in the MB dye photodegradation.•The 3% La-doped NiO showed excellent chemical stability and reusability. Herein, pure NiO and La-doped NiO nanoparticles have been prepared by a simple coprecipitation method. As synthesized samples were broadly characterized using X-ray diffraction spectroscopy (XRD), X-ray Photoelectron Spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Energy-disperse X-ray spectroscopy (EDS), UV– Visible absorption spectroscopy (UV), and Photoluminus (PL) techniques. The La-doped NiO NPs exhibited excellent photocatalytic activity for methylene blue (MB) dye degradation under visible light irradiation. The density functional theory (DFT) studies have also been undertaken for NiO and La-doped NiO NPs to understand the linear optical and chemical properties. It is discovered that there is a good correlation between the experimental results and the Theoretical results. The 3% La-NiO sample showed a high specific surface area of 72.82 m2/g. The La-doped NiO nanoparticles showed more significant photocatalytic activity than pure NiO. Effectively, 3% La-doped NiO's degradation efficiency is 95.1%, and the rate constant is 0.02178 cm−1, higher than pure NiO. The trapping test confirmed that •OH and •O2– are the main active species participating in photocatalytic activity. The 3% La-NiO showed 76% of total organic carbon (TOC) removed effectively. Furthermore, after four consecutive tests, 3% La-doped NiO exhibited superior photocatalytic performance. The possible MB dye degradation mechanism over La-doped NiO photocatalyst is proposed.