Photoelectrochemical study of novel solar light n-p heterojunction photocatalyst including molybdates decorated on RGO nanosheets for dye degradation of wastewater

• Published in: Journal of the Iranian Chemical Society 2022-05, Vol.19 (5), p.2005-2021
• Main Authors: Ramezanalizadeh, Hamed, Rafiee, Ezzat
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Biochemistry; Catalysts; Catalytic activity; Chemistry; Chemistry and Materials Science; Dyes; Electronic properties; Graphene; Heterojunctions; Inorganic Chemistry; Light irradiation; Molybdates; Nanocomposites; Nanosheets; Nickel compounds; Organic Chemistry; Original Paper; Performance evaluation; Photocatalysis; Photocatalysts; Photodegradation; Physical Chemistry; Stability tests; Surface resistance; Wastewater
• ISSN: 1735-207X; 1735-2428
• DOI: 10.1007/s13738-021-02440-4

Different types of metal molybdates were decorated into the reduced graphene oxide (RGO) nanosheets via a straightforward approach. RGO/NiMoO 4 nanocomposite showed the best activity for the photodegradation of dye under visible light irradiation. To evaluate the photocatalytic performance of RGO/NiMoO 4 , the effect of various parameters was evaluated and the role of every involved species was explained in detail. Results showed that more than 95% dye photodegradation was obtained at dye concentration 5 ppm, pH 3 and catalyst loading of 1 g/L as optimum conditions. The superior photocatalytic activity of RGO/NiMoO 4 can be ascribed to the efficient light harvesting, lowest electron–hole recombination, easy and remarkable electron-transferring properties, and suitable electronic properties of RGO sheets. Mott–Schottky plots showed different flat band potential and donor density for different kinds of photocatalysts and effect of pH on n- or p-type behavior of heterojunction. RGO/NiMoO 4 was selected because of more negative E fb , and also there are no significant differences in E fb at pH 3 and 7. The Nyquist and Bode plots of the samples showed an efficient separation of the photo-generated electrons and holes, lifetime and confirmed the existence of small surface resistance for prepared photocatalysts. Lifetime for RGO/NiMoO 4 was 125.89 ms at pH 3 compared with 13.2, 19.22, 6.22 19.22 and 5.94 ms for RGO/CoMoO 4 , RGO/CuMoO 4 , RGO/FeMoO 4 , NiMoO 4 and RGO, respectively. Utilization of different scavengers in the trapping experiment showed that the ( 1 O 2 ) and h + are the major involved species in the photocatalytic system. Reusability and stability tests showed that the catalyst could be reused four times. To figure out the successful synthesis of RGO/NiMoO 4 nanocomposite, XRD, FT-IR, DRS, XPS, ICP-OES, FESEM, and EDS mapping characterization techniques were employed. Graphic abstract