Crumpled graphene nanoreactors

Abstract

Nanoreactors are material structures that provide engineered internal cavities that create unique confined nanoscale environments for chemical reactions. Crumpled graphene nanoparticles or "nanosacks" may serve as nanoreactors when filled with reactive or catalytic particles and engineered for a specific chemical function. This article explores the behavior of crumpled graphene nanoreactors containing nanoscale ZnO, Ag, Ni, Cu, Fe, or TiO2 particles, either alone or in combination, in a series of case studies designed to reveal their fundamental behaviors. The first case study shows that ZnO nanoparticles undergo rapid dissolution inside the nanoreactor cavity accompanied by diffusive release of soluble products to surrounding aqueous media through the irregular folded shell. This behavior demonstrates the open nature of the sack structure, which facilitates rapid small-molecule exchange between inside and outside that is a requirement for nanoreactor function. In a case study on copper and silver nanoparticles, encapsulation in graphene nanoreactors is shown in some cases to enhance their oxidation rate in aqueous media, which is attributed to electron transfer from the metal core to graphene that bypasses surface oxides and allows reduction of molecular oxygen on the high-area graphene shell. Nanoreactors also allow particle-particle electron transfer interactions that are mediated by the connecting conductive graphene, which give rise to novel behaviors such as galvanic protection of Ag nanoparticles in Ag/Ni-filled nanoreactors, and the photochemical control of Ag-ion release in Ag/TiO2-filled nanoreactors. It is also shown that internal graphene structures within the sacks provide pockets that reduce particle mobility and inhibit particle sintering during thermal treatment. Finally, these novel behaviors are used to suggest and demonstrate several potential applications for graphene nanoreactors in catalysts, controlled release, and environmental remediation.

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Aerosol synthesis of phase-controlled iron–graphene nanohybrids through FeOOH nanorod intermediates

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From Flatland to Spaceland: Higher Dimensional Patterning with Two‐Dimensional Materials

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“…c) Catalytic reduction of CO 2 : catalytic activity of Cu‐graphene microparticles for the electrochemical reduction of CO 2 in 0.1 M aqueous KHCO 3 . The inset plot shows the activity of the Cu foil and Cu‐graphene hybrids normalized by copper mass, showing the much higher activity of the nanosack system . Reproduced with permission .…”

“…The inset plot shows the activity of the Cu foil and Cu‐graphene hybrids normalized by copper mass, showing the much higher activity of the nanosack system . Reproduced with permission . Copyright 2015, Royal Society of Chemistry.…”