Versatile Functionalization of Carbon Nanomaterials by Ferrate(VI)

Abstract

Highlights

• Various forms of carbon nanomaterials are selected as substrates to clear the mist in understanding the reactivity/utility of ferrate(VI) in oxidizing carbon nanomaterials.

• It unravels a modest reactivity of ferrate(VI) in liquid phase that only oxidizes the active defects on carbon surface and a powerful oxidizing ability in solid state that can open the inert C=C bonds in carbon lattice.

• Respective benefit and limitation of the wet and dry approaches using ferrate(VI) in functionalizing carbon nanomaterials are discussed.

As a high-valent iron compound with Fe in the highest accessible oxidation state, ferrate(VI) brings unique opportunities for a number of areas where chemical oxidation is essential. Recently, it is emerging as a novel oxidizing agent for materials chemistry, especially for the oxidation of carbon materials. However, the reported reactivity in liquid phase (H₂SO₄ medium) is confusing, which ranges from aggressive to moderate, and even incompetent. Meanwhile, the solid-state reactivity underlying the “dry” chemistry of ferrate(VI) remains poorly understood. Herein, we scrutinize the reactivity of K₂FeO₄ using fullerene C₆₀ and various nanocarbons as substrates. The results unravel a modest reactivity in liquid phase that only oxidizes the active defects on carbon surface and a powerful oxidizing ability in solid state that can open the inert C=C bonds in carbon lattice. We also discuss respective benefit and limitation of the wet and dry approaches. Our work provides a rational understanding on the oxidizing ability of ferrate(VI) and can guide its application in functionalization/transformation of carbons and also other kinds of materials.