(663e) Super Oleophilic and Water Repellent Graphene Oxide Sponge for Catalytic Coupling of Furanics

Improved
Graphene Oxide Sponge as Superoleophilic Furan Coupling Catalyst

Saikat
Dutta, Dionisios G. Vlachos, Basudeb Saha

Hydrophobic
materials with repeatable adsorption for oils due to superior oleophilicity
also promotes surface adsorption of organics that may promote a chemical
reaction. Such dual features in the same material may elevate the application
profile from efficient oil absorber to a potential surface-active catalyst in
the liquid phase. Graphene materials have been reported for multipurpose
absorption applications both in hydrophobic and hydrophilic environments due to
incredibly controllable surface wettability. Hydrothermally convertible surface
features of a improved graphene oxide (IGO) into its hierarchical form such as graphene
oxide foam (GOF) represents a new generation of amorphous carbon materials that
offers multipurpose adsorption based applications. The GOF with 3D
microstructures enhances surface roughness of parent graphene sheets and
propensity for rapid adsorption. A mammoth scope of achieving aggregation state
of GO through self-assembly has enabled researchers to develop
carbon-frameworks with desired physical and microstructural properties.

In this presentation, we aim to describe
how the multilayer IGO is capable of forming IGO-assembly with and without a
cross-linker (phytic acid (PA)) to access to IGO-foams (IGO-PA and IGO-H)
(Scheme 1). Carbon-frameworks of these IGO-foams are amorphous and possess
similar surface features as found in parent IGO as revealed from X-ray
diffraction (XRD) analysis. Spectroscopic (Raman, XPS) and microscopic imaging
(SEM, HRTEM, AFM) techniques reveal multiple type of surface functional groups
and extended twisted sheet like multilayered arrangement of graphene sheets in both
foam materials. These foams are also incredibly water-repellent
(superhydrophobic) and superoleophilic that enables their use for oil
absorption in large volume from water-oil mixture. IGO-H was demonstrated as
being capable for absorption of oils drops moving on the widely spread water
surface which resembles oil-spill scenario in the sea. As a results of a unique
balance between hydrophobicity

Both IGO-PA and IGO-H foams exhibits
excellent catalytic activity for C-C coupling of low carbon furanics to long
carbon fuel precursors via hydroxyalkylation/alkylation (HAA) reaction under
solventless conditions at low temperatures.  Considering chemical and thermally
tunable hydrophobic and oleophilic surface features, a wide-range of
application for which IGO-foams fit which also includes advanced biomass
processing based on adsorption.

Scheme 1. Preparation
protocol of IGO-sponges under hydrothermal condition and its oil-absorption
features from oil-water biphasic medium and catalytic applications for solventless
HAA of furanics.