Revisiting the chemistry of graphite oxides and its effect on ammonia adsorption

By C. Petit, M. Seredych, T. Bandosz. 2009

252 citations recorded by the source corpus.

Graphite oxide (GO) was synthesized using two different methods: one with sulfuric acid as part of the oxidizing mixture (Hummers–Offeman method) and another one without the sulfur-containing compound involved in the oxidation process (Brodie method). They were both tested for ammonia adsorption in dynamic conditions, at ambient temperature, and characterized before and after exposure to ammonia by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, potentiometric titration, energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS) and elemental analysis. Analyses of the initial materials showed that besides epoxy, hydroxyl and carboxylic groups, a significant amount of sulfur is incorporated as sulfonic group for GO prepared by the Hummers–Offeman method. The process of ammonia adsorption seems to be strongly related to the type of GO. For GO prepared by the Brodie method, ammonia is mainly retained via intercalation in the interlayer space of GO and by reaction with the carboxylic groups present at the edges of the graphene layers. On the contrary, when GO prepared by the Hummers method is used, the ways of retention are different: not only is the intercalation of ammonia observed but its reaction with the epoxy, carboxylic and sulfonic groups present is also observed. In particular, during the ammonia adsorption process, sulfonic groups are converted to sulfates in the presence of superoxide anions O2−*. These sulfates can then react with ammonia to form ammonium sulfates. For both GOs, an incorporation of a significant part of the ammonia adsorbed as amines in their structure is observed as a result of reactive adsorption.

Subfields: Electronic, Optical and Magnetic Materials, Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/96320fbdc6ffa7224171e88f9cd49c3456b271b8

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Citations in the corpus

Graphene oxide. Origin of acidity, its instability in water, and a new dynamic structural model. (2013, background): “In the literature, the relative intensities of the bands in this region and their interpretation differ from work to work and from sample to sample.(7,10,17,19,25) We think that due to the overlapping of many different bands, definitive assignment in this region is difficult.”
Adsorptive remediation of environmental pollutants using novel graphene-based nanomaterials (2013, result): “[46] further compared two GO samples synthesized from the Hummers–Offeman and Brodie methods for ammonia adsorption and found that ammonia adsorption is strongly related to the type of GO.”
The synthesis and characterization of copper-based metal–organic framework/graphite oxide composites (2011, methodology): “The first band can be assigned to epoxy/peroxide groups and the second to S@O asymmetric stretching vibration in sulfonic groups and/or vibration of C– O in epoxides [26].”
Studies of Reduced Graphene Oxide and Graphite Oxide in the Aspect of Their Possible Application in Gas Sensors (2016, unknown): “4 eV assigned to C–C, C–O, C=O, O–C–O, O=C–OH and π–π* transition in aromatic systems [28].”
Graphene-based materials: synthesis and gas sorption, storage and separation (2015, background): “On the contrary, the NH3 reaction with the epoxy, carboxylic and sulphonic groups is observed in the Hummers GO [305].”
Direct laser writing of micro-supercapacitors on hydrated graphite oxide films. (2011, background): “We speculate that protons, which are the species taking part in ionic conduction, arise from hydrolysis of the functional groups (carboxyl, sulphoni”