Abstract
The paper presents a comparative study of the activity of magnetite (Fe3O4) and copper and cobalt ferrites with the structure of a cubic spinel synthesized by combustion of glycine-nitrate precursors in the reactions of ammonia borane (NH3BH3) hydrolysis and hydrothermolysis. It was shown that the use of copper ferrite in the studied reactions of NH3BH3 dehydrogenation has the advantages of a high catalytic activity and the absence of an induction period in the H2 generation curve due to the activating action of copper on the reduction of iron. Two methods have been proposed to improve catalytic activity of Fe3O4-based systems: (1) replacement of a portion of Fe2+ cations in the spinel by active cations including Cu2+ and (2) preparation of highly dispersed multiphase oxide systems, involving oxide of copper.
Highlights
Ammonia borane (NH3 BH3, AB) is an extensively studied hydride and dozens of review articles have already appeared discussing the results of these studies [1,2,3,4,5,6,7,8,9,10]
The high hydrogen content of this hydride (19.6 wt%) allows it to be applied in a variety of fields: as hydrogen storage systems to generate hydrogen for the needs of hydrogen economy [1,2,3,4,5,6,7,8,9,10], as a component of fuels [11,12], as a reducing agent in fine organic synthesis [13] and in the synthesis of metallic nanoparticles [14,15]
The addition of copper into these oxides and its effect on the catalytic activity in the water-employing process of AB dehydrogenation remain practically unstudied. This is, in Materials 2021, 14, 5422 part, explained by the fact that in an article published in 2018 [45]—a series of metal ferrites prepared by precipitation were tested in the process of AB hydrolysis, showing rather low activity which increased in the order NiFe2 O4 < CuFe2 O4 < ZnFe2 O4 < MnFe2 O4, i.e., nickel- and copper-ferrite-containing metals, usually active in the AB hydrolysis—
Summary
Ammonia borane (NH3 BH3 , AB) is an extensively studied hydride and dozens of review articles have already appeared discussing the results of these studies [1,2,3,4,5,6,7,8,9,10]. It was confirmed by X-ray photoelectron spectroscopy (XPS) that the addition of copper accelerates the reduction of other metal cations comprising the complex oxide This evidence was explained as follows: Cu2+ (0.337 V vs SHE) are primarily reduced in the reaction medium to form Cu0 particles containing hydridic Cu-H bonds on their surface. The addition of copper into these oxides and its effect on the catalytic activity in the water-employing process of AB dehydrogenation remain practically unstudied This is, in Materials 2021, 14, 5422 part, explained by the fact that in an article published in 2018 [45]—a series of metal ferrites prepared by precipitation were tested in the process of AB hydrolysis, showing rather low activity which increased in the order NiFe2 O4 < CuFe2 O4 < ZnFe2 O4 < MnFe2 O4 , i.e., nickel- and copper-ferrite-containing metals, usually active in the AB hydrolysis—. Comparing the activities of combustion products prepared under different synthesis conditions, and having different phase compositions, will help to reveal the key characteristics of an active catalyst (the content of the cubic spinel and the content of copper in its structure as well as the presence in the sample of active copper-containing impurity)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
