Liquid‐phase exfoliation method to access cobalt oxide nanosheets in pH‐neutral solutions

Abstract

Two-dimensional materials have gained significant attention across the materials community due to their remarkable physical, chemical, electronic, and optical properties. With many two-dimensional materials discovered each year, investigations into their processing, scalability, and resulting properties are important to fully realize their potential in next-generation technologies. While numerous exfoliation techniques are available for a variety of two-dimensional materials, liquid-phase exfoliation techniques offer many advantages, particularly high throughput and scalability. Herein, we report a liquid-phase exfoliation method to access multilayer cobalt oxide nanosheets in pH-neutral aqueous solutions varying in size, concentration, and application. The size, thickness, and morphology of the multilayer nanosheets were confirmed using atomic force microscopy and transmission electron microscopy. Finally, selected cobalt oxide nanosheets underwent additional analysis of the crystallinity, structure, and cobalt valance.

Polymer particles armored with cobalt oxide nanosheets for the catalytic degradation of bisphenol A

“…S1, ESI†): (1) as-received lithium cobalt oxide (LCO) was treated with HCl; then (2) the acid-treated LCO was treated with an aqueous solution of tetramethylammonium hydroxide (TMAOH) to produce TMAOH-treated LCO. 35,43,47–49 The traditional exfoliation method used to produce CONs from LCO yields only a low concentration of nanosheets in highly caustic solution ( i.e. , excess of TMAOH).…”

“…, excess of TMAOH). The modified exfoliation method used here utilized semi-exfoliated TMAOH-treated LCO, rather than the initially exfoliated nanosheets to produce highly concentrated aqueous dispersions of CONs at neutral pH 43 by immersing semi-exfoliated TMAOH-treated LCO particles in DI water and subjecting to bath sonication. After centrifugation, the supernatant was an aqueous dispersion of CONs.…”

“…A suspension of cobalt oxide nanosheets (CONs) dispersed in deionized (DI) water was obtained using the soft-chemical exfoliation method described in detail elsewhere. 43 Briefly, as received lithium cobalt oxide (LCO) powder was treated with 3 M hydrochloric acid (HCl) for 1 day using constant stirring. The acid-treated powder was washed with copious amounts of DI water to remove residual acid or salt and allowed to air dry.…”

“…19 Recent advances in soft-chemical exfoliation of LCO gives access to CONs that are fully dispersible in water. 43 Sonication aided in the exfoliation process and led to nanosheets with thickness of 2–4 nm and lateral widths of >150 nm. We hypothesized that these CONs could be used as the sole surfactant ( e.g.…”

Engineering Multifunctional Stratified LiCoO2 Catalysts: Structural Disorder to Microstructural Exfoliation

“…Such alternative applications may become critical owing to the high level of waste generated from the widespread use of Li-ion batteries. In addition, the exfoliation of lithium cobalt oxide is sparsely reported. − Limited methods for the exfoliation of bulk LCO methods have been described, including chemical leaching, , intercalation of large cations, , or thermal treatment . The processing methods result in different products in terms of size and thickness, which may result in variations in performance.…”