Design of MgO/graphene nanocomposites for photocatalytic reduction of 4-nitrophenol and electrocatalytic oxidation of Methylene blue dye

The present study deals with the combustion synthesis of MgO/Graphene (MG) nanocomposites and investigates their photocatalytic, electrocatalytic, and photo-electrocatalytic properties for efficient redox reactions. Techniques such as FT-IR, XRD, SEM, HR-TEM, EDX, BET, and UV–vis-DRS were used to characterize MG nanocomposites. Both the photocatalytic degradation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and the electrocatalytic results of the MG2 nanocomposite were studied under visible light. The results showed that the MG2 nanocomposite catalyst achieved 99.07% degradation of MB dye and kinetic degradation rates of 0.114 min −1 after 40 min, compared to the catalytic activity of MG0. Thus, facile modification can effectively improve the photocatalytic reduction (toxic 4-NP to beneficial 4-AP) and electrocatalytic degradation (MB) abilities of MG0. The functions of active species in the catalytic process were investigated using various scavengers. The ·OH radicals are the reactive species responsible for the 4-NP reduction, and a possible mechanism for improved catalytic activities was also provided. Incorporating graphene under visible light boosted the MG’s activity and confirmed it to be the most effective method for handling MB dye.