Issue 25, 2018

Graphene inclusion controlling conductivity and gas sorption of metal–organic framework

Abstract

A general approach to prepare composite films of metal–organic frameworks and graphene has been developed. Films of copper(II)-based HKUST-1 and HKUST-1/graphene composites were grown solvothermally on glassy carbon electrodes. The films were chemically tethered to the substrate by diazonium electrografting resulting in a large electrode coverage and good stability in solution for electrochemical studies. HKUST-1 has poor electrical conductivity, but we demonstrate that the addition of graphene to HKUST-1 partially restores the electrochemical activity of the electrodes. The enhanced activity, however, does not result in copper(II) to copper(I) reduction in HKUST-1 at negative potentials. The materials were characterised in-depth: microscopy and grazing incidence X-ray diffraction demonstrate uniform films of crystalline HKUST-1, and Raman spectroscopy reveals that graphene is homogeneously distributed in the films. Gas sorption studies show that both HKUST-1 and HKUST-1/graphene have a large CO2/N2 selectivity, but the composite has a lower surface area and CO2 adsorption capacity in comparison with HKUST-1, while CO2 binds stronger to the composite at low pressures. Electron paramagnetic resonance spectroscopy reveals that both monomeric and dimeric copper units are present in the materials, and that the two materials behave differently upon hydration, i.e. HKUST-1/graphene reacts slower by interaction with water. The changed gas/vapour sorption properties and the improved electrochemical activity are two independent consequences of combining graphene with HKUST-1.

Graphical abstract: Graphene inclusion controlling conductivity and gas sorption of metal–organic framework

Supplementary files

Article information

Article type
Paper
Submitted
20 mar 2018
Accepted
02 apr 2018
First published
16 apr 2018
This article is Open Access
Creative Commons BY license

RSC Adv., 2018,8, 13921-13932

Graphene inclusion controlling conductivity and gas sorption of metal–organic framework

P. Lamagni, B. L. Pedersen, A. Godiksen, S. Mossin, X. Hu, S. U. Pedersen, K. Daasbjerg and N. Lock, RSC Adv., 2018, 8, 13921 DOI: 10.1039/C8RA02439A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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