Graphene oxide paper or graphite oxide paper is a
material
Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geolo ...
fabricated from
graphite oxide
Graphite oxide (GO), formerly called graphitic oxide or graphitic acid, is a compound of carbon, oxygen, and hydrogen in variable ratios, obtained by treating graphite with strong oxidizers and acids for resolving of extra metals. The maximally o ...
. Micrometer thick films of graphene oxide paper are also named as graphite oxide membranes (in the 1960s) or (more recently) graphene oxide membranes. The membranes are typically obtained by slow evaporation of graphene oxide solution or by the filtration method.
The material has exceptional
stiffness and
strength
Strength may refer to:
Physical strength
*Physical strength, as in people or animals
* Hysterical strength, extreme strength occurring when people are in life-and-death situations
*Superhuman strength, great physical strength far above human c ...
, due to the intrinsic strength of the two-dimensional
graphene
Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. backbone and to its interwoven layer structure which distributes loads.
Preparation
The starting material is water-dispersed graphene oxide flakes. The aqueous dispersion is vacuum filtrated to produce free standing foils. The thickness of these foils is typically in the range of 0.1-50 micrometers. Depending on application the graphene oxide laminates are named either as papers or as membranes. Alternative methods to prepare free standing graphene oxide multilayers/laminates is to use repeated drop casting or spin coating. These flakes may be
chemical bond, chemically bonded, leading to the development of additional new materials. Like the starting material, graphene oxide paper is an
electrical insulator
An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and conductors—conduct electric current ...
; however, it may be possible to tune this property, making the paper a
conductor or
semiconductor
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...
, without sacrificing its mechanical properties.
Properties
Detailed studies of graphite oxide paper by V. Kohlschütter and P. Haenni date back to 1918.
Studies of
graphite oxide
Graphite oxide (GO), formerly called graphitic oxide or graphitic acid, is a compound of carbon, oxygen, and hydrogen in variable ratios, obtained by treating graphite with strong oxidizers and acids for resolving of extra metals. The maximally o ...
membranes were performed by
Hanns-Peter Boehm
Hanns-Peter Boehm (9 January 1928 – 10 May 2022) was a German chemist and professor emeritus at Ludwig-Maximilians-Universität in Munich, Germany. Boehm is considered a pioneer of graphene research.
Biography
Hanns-Peter Boehm studied che ...
, the German scientist who invented the term "graphene", in 1960. The paper titled "Graphite Oxide and its membrane properties" reported synthesis of "paper-like foils" with 0.05 mm thickness. The membranes were reported to be not permeable by gases (nitrogen and oxygen) but easily permeable by water vapors and, suggestively, by any other solvents which are able to intercalate graphite oxide. It was also reported that the membranes are not permeable by "substances of lower molecular weight".
Permeation of water through the membrane was attributed to swelling of graphite oxide structure which enables water penetration path between individual graphene oxide layers. The interlayer distance of dried graphite oxide was reported as 6.35 Å, but in liquid water it increased to 11.6 Å. Remarkably, the paper also cited the inter-layer distance in diluted NaOH as infinity thus reporting dispersion of graphite oxide on single-layered graphene oxide sheets in solution. The study also reported permeation rate of membranes for water 0.1 mg per minute per square cm. The diffusion rate of water was evaluated as 1 cm/hour. Boehm's paper also showed that graphite oxide can be used as cation exchange membrane and reports measurements of
osmotic pressures, membrane potentials in KCl, HCl, CaCl
2, MgCl
2, BaCl
2 solutions. The membranes were also reported to be permeable by large
alkaloid ion
Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar st ...
s as they are able to penetrate between graphene oxide layers.
In 2012 some of the properties of graphite oxide membranes discovered by Boehm were re-discovered: the membranes were reported to be not permeable by helium but permeable by water vapors.
This study was later expanded to demonstrate that several salts (for example KCl, MgCl
2) diffuse through the graphene oxide membrane if it is immersed in water solution.
Graphene oxide membranes are actively being studied for their applications to
water desalination
Desalination is a process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance, as in soil desalination, which is an issue for agriculture. Salt ...
.
Retention rates over 90% were reported in a 1960 study for NaCl solutions using stabilized graphene oxide membranes in
reverse osmosis setup.
See also
*
Nanotechnology
*
Buckypaper
Buckypaper is a thin sheet made from an aggregate of carbon nanotubes or carbon nanotube grid paper. The nanotubes are approximately 50,000 times thinner than a human hair. Originally, it was fabricated as a way to handle carbon nanotubes, but i ...
*
Carbon nanotube
*
Graphene oxide
An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the ...
References
Graphene Oxide Paper Could Spawn a New Class of Materials(Northwestern University Press Release)
Graphene oxide weaved into 'paper'(physicsworld.com)
It's Super Paper!(ScienceNOW Daily News)
Ultrastrong Paper from Graphene(Technology Review)
(Nature)
External links
Graphene Oxide Paper Fabrication Technology Abstract*
ttps://web.archive.org/web/20070928070958/http://intl.emboj.org/nature/journal/v448/n7152/full/nature06016.html Preparation and characterization of graphene oxide paper(Nature)
{{DEFAULTSORT:Graphene Oxide Paper
Graphene