Indulgent of the physiochemical features of MgCr-LDH nanosheets towards photodegradation process of methylene blue

• Published in: Journal of colloid and interface science 2023-03, Vol.634, p.121-137
• Main Authors: Nayak, Susanginee, Kumar Das, Kundan, Parida, Kulamani
• Format: Article
• Language: English
• Subjects: Hydroxides - chemistry; Methylene Blue - chemistry; Methylene blue degradation; MgCr-LDH nanosheets; Oxygen vacancies; Photocatalysis; Photolysis; Solitary catalyst; X-Ray Diffraction
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2022.12.050

Synopsis: MgCr-LDH nanosheets with formamide induced mild hydrothermal treatment could efficiently degraded methylene blue dye under visible light exposure. [Display omitted] •MgCr-LDH nanosheets were formed by formamide used co-precipitation and hydrothermal.•MgCr-LDH nanosheets possess 90% degree of delamination.•MgCr-LDH nanosheets showed MB degradation of 90.6% at 2 h under sunlight exposure.•Organization of uni/multi-lamellar nanosheets in MgCr-LDHs trips the performances.•The –OH groups of LDHs with valence band holes deal the •OH radicals for activity. In the present work, we report the preparatory strategy of MgCr-layered double hydroxide (LDH) nanosheets with 90% degree of delamination by employing a formamide-assisted co-precipitation and mild hydrothermal route for the degradation of methylene blue (MB) under solar light exposure. The as-synthesized MgCr-LDH nanosheets were characterized by assorted characterization techniques such as powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Raman, thermogravimetric analysis (TGA), N2 adsorption–desorption measurement, X-ray photoelectron spectroscopy (XPS) and UV–Visible diffused reflectance spectroscopy (UV-DRS). The XRD pattern of MgCr-LDH nanosheets quantified the strain (ε) and dislocation density (δ) of 1.371 lines−2 m−4 and 0.5723 lines m−2 related to the (110) plane with d-spacing value of 1.6169 Ȧ. With a minimum band gap of ∼2.63 eV, the as-synthesized MgCr-LDH nanosheets displayed 90.6% MB photodegradation under the experimental protocols such as catalyst dosage of 30 mg/L, initial MB concentrations of 20 ppm, pH of 7 and time duration of 2 h under solar light exposure. Further, the recyclability test of the photocatalyst signifies material stability up to four successive cycles with 90% retention of MB degradation under sunlight exposure. The superior catalytic performances of the MgCr-LDH nanosheets could be ascertained to the suppression of excitonic recombination and effective light harvestation properties, synergistically contributed by the porous structural aspects via association of uni/multi-lamellar nanosheets, surface defect sites and photoactive Cr3+ cations. Additionally, the surface –OH groups of LDH contributed towards the generation of •OH radicals for triggering the catalytic performances. This type of work advances the novel ideas for establishing highly potent photocatalysts via synergizing structur