Ferromagnetism and Structural Features of N-doped Graphene Clusters in Carbon Structures

We report that nitrogen pressure and the chemistry of the initial reagents are the efficient parameters for controlling the electron characteristics of produced carbonaceous materials, consequently affecting their magnetic properties. By manipulating these parameters, we successfully altered the sp3 /sp2 ratio within a range of 1 to 2.8 and the pyridinic-N/pyrrolic-N ratio within a range of 0.6 to 1.3. The growth of the sp3 /sp2 ratio coincided with a decrease in the fraction of pyridinic nitrogen and an increase in pyrrolic nitrogen. The magnetic properties of the materials were measured at two different temperatures (5 and 300 K) and external magnetic fields of up to 50 kOe. It was shown that increasing the sp3 /sp2 ratio led to an increase of the ferromagnetic component of the magnetic moment. This correlation was observed at both 300 K and 5 K. The explanations of the observed effects are also suggested and discussed.</p

Combustion synthesis: A novel method of catalyst preparation

In this chapter, we summarize work accomplished primarily by the authors on the use of solution combustion synthesis (SCS) in catalysis. Research in combustion synthesis at University of Notre Dame started with the group of Prof. A. Varma, now at Purdue University, in collaboration with Prof. A. Mukasyan and its application to catalysis was pursued jointly with Prof. E. Wolf. Prof. A. Kumar worked on the subject during his graduate studies at Notre Dame and now he is continuing work on the application of combustion synthesis to catalysis at Qatar University. After an introduction to combustion synthesis, we describe reaction pathways involved in the preparation of unsupported and supported catalysts using SCS. The catalytic applications focus on preparation and performance of active and stable catalysts for the hydrogen generation from methanol and ethanol, followed by application to electrocatalysis for fuels cell utilization. - The Royal Society of Chemistry 2019.We gratefully acknowledge the support of this work by grant NPRP-8-509-2-209 from the Qatar National Research Fund (member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

In situ XAS and FTIR studies of a multi-component Ni/Fe/Cu catalyst for hydrogen production from ethanol

Multicomponent catalysts containing Ni, Fe, Cu active for ethanol reforming reactions, prepared by solution combustion synthesis are characterized by multiple techniques such as ex situ XRD, XPS, and in situ XAFS and FTIR. XRD results indicate copper to be present in the reduced state as CuNi bimetal while nickel and iron are observed to be partially in a spinel NiFe2O 4 structure. In situ XANES and XAFS analysis show a change in Ni, Fe and Cu oxidation states during reaction. Cu, which was fully reduced before reaction, became partly oxidized upon exposure to ethanol and oxygen. Ni is mostly (75%) reduced and does not seem to change its oxidation state during the reaction. Fe is not present in metallic form after reduction and during the reaction, but some change in the oxidation state from Fe(II) to Fe(III) occurred during the reaction. XPS and SEM images indicate the formation of carbon filament on the spent catalyst. XPS results also indicate the enrichment of surface by Fe and Cu during the reduction of the catalyst. Based on the activity and characterization results obtained, and literature review, the role of predominant phases during ethanol decomposition reaction is proposed.We gratefully acknowledge funding from NSF grant 0730190 for support of this work. This work was also partially supported by Notre Dame Integrated Imaging Facility . Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under contract DE-AC02-06CH11357.Scopu

Combustion synthesis of copper-nickel catalysts for hydrogen production from ethanol

Cu and Ni based catalysts were synthesized using solution combustion synthesis method. The catalytic activity and hydrogen selectivity were investigated for ethanol decomposition reaction. The amount of fuel content in the combustion solution was found to greatly affect the phase and the microstructure of the synthesized catalyst. In situ X-ray absorption spectroscopy (XAS) studies were carried out to study the reduction of the catalyst containing mixed oxides of copper and nickel. The reduced catalyst was further subjected to an oxidizing environment to collect the in situ XAS data during the oxidation of the catalyst. These investigations show that the catalyst oxidation state changes rapidly in the first few minutes of the pretreatment process and then gradually slows downs.We gratefully acknowledge the funding from NSF Grant 0730190 to support this work (AK and EEW). Use of the Advanced Photon Source is supported by the U. S. Department of Energy, Office of Science, and Office of Basic Energy Sciences , under Contract DE-AC02-06CH11357 . We also acknowledge the Notre Dame Integrated Imaging Facility for its support in conducting SEM experiments. AK would also like to acknowledge the funding from Qatar National Research Fund (QNRF) to support the synthesis work at Qatar University. This publication was made possible by JSREP Grant ( JSREP-05-004-2-002 ) from the Qatar national research fund (a member of Qatar foundation). The statements made herein are solely the responsibility of the author(s).Scopu