Ultrafast synthesis of exfoliated manganese oxides in deep eutectic solvents for water purification and energy storage

[Display omitted] •A facile approach for the rapid preparation of exfoliated manganese oxide in 1 min.•Utilization of deep eutectic solvents as solvent cum reducing agents.•Engineering of material to a membrane form for superior flux and rejection.•Material for supercapacitor with exquisite electrochemical performance. In the present study, we explore a facile route for the ultrafast preparation of nanostructured MnxOy at room temperature in a short reaction time using KMnO4 as precursor and deep eutectic solvents (DESs; such as CC-EG, CC-Glucose, and CC-EG-Glucose) as ecofriendly solvent cum reducing agent. A detailed study was undertaken to examine the reaction kinetics of MnxOy preparation using various analytical tools. Under optimized process conditions magnificent water flux of 5736 Lm−2h−1 for dye contaminated feed with excellent rejection of >99% was achieved with a maximum adsorption capacity of 253 mg.g−1, whereas the recyclability studies ensured >93% rejection even after 10cycles. Moreover, the prepared symmetric coin cells showed a high specific capacitance of 207 Fg−1 at a mass specific current of 0.05 Ag−1. Also the device exhibits a respectable rate capability of 63.57% in-between the current density range of 1–10 Ag−1 with a capacitance of 151–96 Fg−1. Cyclic stability studies revealed that the material can be stable with a capacity retention of 80.5% and 69.4% after 5000 and 10,000 cycles respectively, with a coulombic efficiency of 100%. In addition to that the material illustrated with a high energy density 18.37 Wh.kg−1 (at 0.05 Ag−1) and power density 24,000 W.kg−1 (at 30 Ag−1).