Influence of cobalt substitution on the crystal structure, band edges and photocatalytic properties of hierarchical Bi 2 WO 6 microspheres

• Published in: New journal of chemistry 2019-06, Vol.43 (23), p.9170-9182
• Main Authors: Kavinkumar, Veerappan, Jaihindh, Dhayanantha Prabu, Verma, Atul, Jothivenkatachalam, Kandasamy, Fu, Yen-Pei
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C9NJ00170K

An efficient Bi 2 WO 6 catalyst with Co 2+ substitution was synthesized via a facile hydrothermal route, and the materials were characterized by P-XRD, FT-IR, FE-SEM, XPS, DRS, BET and PL techniques. The obtained Co 2+ substituted Bi 2 WO 6 materials displayed high photocatalytic activity for organic dye degradation; 97.5% of the dye was photodegraded by 5 mol% of Co 2+ substituted Bi 2 WO 6 within 240 min induced by the visible light, which was remarkably better than the degradation of the bare and Co 2+ substituted Bi 2 WO 6 (1, 3, 7 and 9% Co 2+ concentration). Based on the structural, optical and elemental characterization, it was determined that the substitution of the Co 2+ ions in the Bi 2 WO 6 lattice to replace the W 6+ ion sites occurred without substantial changes in the crystal structure. The substituent Co 2+ played a strategic role, which narrowed the band gap, leading to an enlargement in visible light absorption ability and suppressing the recombination of photogenerated electron–hole pairs credited to the Co 2+ inner energy state. Additionally, the photocatalytic mechanism was elucidated by performing the radical trapping experiments, which disclosed that holes (h + ) were the main species responsible for the RhB degradation. In addition, the stability of the catalysts was tested by performing recycling experiments. After the four repeating cycles, the degradation efficiency was not dramatically reduced. The results of this study disclosed that Co 2+ substitution of W 6+ may offer an alternative approach to enhance the Bi 2 WO 6 photocatalytic activity.