Manganese oxide nanosheets and a 2D hybrid of graphene–manganese oxide nanosheets synthesized by liquid-phase exfoliation

Abstract

E -m a i l : b e a t r i x . m e n d o z a @ g m a i l . c o m"These authors contributed equally to this work Abstract Manganese oxide nanosheets were synthesized using liquid-phase exfoliation that achieved suspensions in isopropanol with concentrations of up to 0.45 mg ml -1 . A study of solubility parameters showed that the exfoliation was optimum in N,N-Dimethylformamide followed by isopropanol and diethylene glycol. Isopropanol was the solvent of choice due to its environmentally friendly nature and ease of use for further processing. For the first time, a hybrid of graphene and manganese oxide nanosheets was synthesized using a single-step co-exfoliation process. The 2D hybrid was synthesized in isopropanol suspensions with concentrations of up to 0.5 mg ml -1 and demonstrated stability against re-aggregation for up to 6 months. The co-exfoliation was found to be a energetically favorable process in which both solutes, graphene and manganese oxide nanosheets, exfoliate with an improved yield as compared to the single-solute exfoliation procedure. This work demonstrates the remarkable versatility of liquid-phase exfoliation *To whom correspondence should be addressed 2 with respect to the synthesis of hybrids with tailored properties, and it provides proof-of-concept ground work for further future investigation and exploitation of hybrids made of two or more 2D nanomaterials that have key complementary properties for various technological applications.

Effect of Percolation on the Capacitance of Supercapacitor Electrodes Prepared from Composites of Manganese Dioxide Nanoplatelets and Carbon Nanotubes

“…Layered manganese dioxide was prepared by a modified version 52 of the coprecipitation method described by Jiang et al 45 (see Methods). This procedure results in a brown dispersion containing ~0.2 mg/ml MnO2 dispersed in isopropanol.…”

A 2D graphene-manganese oxide nanosheet hybrid synthesized by a single step liquid-phase co-exfoliation method for supercapacitor applications

“…This diffraction pattern shows the typical sixfold symmetry of graphene [33,26]. Further details regarding the co-exfoliation process and morphology of MON and GMOH are given in a separate work currently accepted for publication [32].…”

“…As shown in the TEM images in Figures 1g−1h, the MON were typically lying on top of graphene. The typical dimensions of graphene were 400 nm lateral size and 6.5 ± 2.4 nm (few layers graphene) [32]. Figure S1 (ESI) shows a diffraction pattern of a graphene flake underlying a MON.…”

Lithium Titanate/Carbon Nanotubes Composites Processed by Ultrasound Irradiation as Anodes for Lithium Ion Batteries

“…Regarding energy storage systems, graphene 20 and MoO 3 21 nanosheets processed by ultrasound irradiation have been successfully tested for thin film supercapacitor applications. The authors have as well recently reported the manufacture of a symmetric supercapacitor based on a MnO 2 /Graphene composite exfoliated in one single step approach 19, 22 . Briefly, this approach relies on the delamination of bulk layered crystals and subsequent stabilization of the obtained two dimensional materials according to solubility parameter laws.…”

“…Moreover, this methodology is also highly scalable in comparison to other traditional synthesis methods 17 . In fact, for the last couple of years, ultrasounds have been widely used to prepare highly stable dispersions of two dimensional nanomaterials 18, 19 . Regarding energy storage systems, graphene 20 and MoO 3 21 nanosheets processed by ultrasound irradiation have been successfully tested for thin film supercapacitor applications.…”