One-Step Rapid Conversion of Electroactive CoMnO Nanostructures Using a Deep Eutectic Solvent as the Template, Solvent, and Source

Abstract

Here, a ternary deep eutectic solvent (DES) is employed as the reaction medium, reducing agent, template, and source for the preparation of cobalt manganese oxide (CoMnO) at room temperature. The hydrogen-bonding interaction between DES and manganese precursors resulted in a rapid conversion of CoMnO nanostructures, and the process was well controlled with the addition of water, which eventually reduced the bonding interaction between the formed nanostructures. The reaction between DES and potassium permanganate is carried out at different time intervals (1, 10, 30, 45, 60 min, 1.5, 2, 4, and 12 h) before the addition of water. With varying reaction times, the morphology, pore structure, surface area, and electrochemical properties of the synthesized CoMnO structures also vary. The highest specific capacitance of 242 F g −1 at 0.1 A g −1 is accomplished using CoMnO nanostructures, where KMnO 4 and ternary DES reacted for 4 h. The CoMnO nanostructures prepared by the DES route also show excellent electrochemical stability with 97% initial capacitance retention at 10 A g −1 over 10 000 charge/discharge cycles. Further, the CoMnO-60 min sample shows outstanding electrochemical OER activity with 300 mV overpotential to obtain a current density of 10 mA cm −2 and a Tafel slope value of 73 mV dec −1 .

Room-Temperature Synthesis of Biogenic δ-MnO2 NPs for the Dehydrogenative Coupling of Diamines with Alcohols for Benzimidazole and Quinoxaline Synthesis: An Efficient Catalyst for Electrochemical Applications

“…The band observed in the range of 600–650 cm –1 corresponds to the frame vibrations of MnO 2 , the vibrational modes of Mn–O–Mn, and the symmetric vibrations of Mn–O in the basal plane of the [MnO 6 ] group. The peak at 628.92 and 637.74 cm –1 of δ-MnO 2 NPs and C-MnO 2 corresponds to A 1g symmetric modes of Mn–O of the [MnO 6 ] octahedra group and the basal plane of [MnO 6 ] . Comparatively, the peak around 637.74 cm –1 (C-MnO 2 ) is shifted toward a lower wavenumber of 628.92 cm –1 in the synthesized δ-MnO 2 NPs, predicting that the decreased effective active force on the atoms is due to the interlayer Vander Waals interactions, and raising the possibility of out-of-plane A1g vibrations results in softening (redshift) of the sample.…”

“…The peak at 12.04°corresponding to the (001) plane confirms the layered structure of δ-MnO 2 NPs with an interlayer spacing of 6.95 A°. 51 Furthermore, the Raman spectrum of δ-MnO 55 Comparatively, the peak around 637.74 cm −1 (C-MnO 2 ) is shifted toward a lower wavenumber of 628.92 cm −1 in the synthesized δ-MnO 2 NPs, predicting that the decreased effective active force on the atoms is due to the interlayer Vander Waals interactions, and raising the possibility of out-of-plane A1g vibrations results in softening (redshift) of the sample. Also, alternative possibility of redshift of band is due to the addition of smaller ions in the catalyst from the active functionalities of GSL.…”

Deep eutectic solvents as an emerging green platform for the synthesis of functional materials

“…Samage et al 173 prepared cobalt–manganese oxides (CoMnO) using ternary deep eutectic solvents (ChCl, Gly, and CoCl 2 ) as precursors (Fig. 22a and b).…”

Electrocatalysis in deep eutectic solvents: from fundamental properties to applications

“…6c ). 121 The hydrogen-bonding interaction between the DES and manganese precursor facilitates the expeditious formation of CoMnO nanostructures. Moreover, this synthesis process and hydrogen-bonding interaction could be regulated by the introduction of water, and water molecules can weaken the bonding between the formed nanostructures and ultimately affect the morphology of CoMnO ( Fig.…”