11:00 AM - EQ09.09.02
Room Temperature and Time-Efficient Plasma-Induced Exsolution in Perovskites Oxides at Atmospheric Pressure
Attaul Haq1,Fiorenza Fanelli2,Hessan Khalid1,Bruno Alessi1,Evangelos Papaioannou3,Kalliopi Kousi3,Ian Metcalfe3,Cristian Savaniu4,John Irvine4,Davide Mariotti1
Ulster University1,National Research Council (CNR), Institute of Nanotechnology (NANOTEC)2,Newcastle University3,University of St Andrews4
Show Abstract
Plasmas are widely used industrially for a wide range of processes including for surface cleaning, inducing functionality to the surfaces, chemical reduction of metal oxides and polymerization etc. Here we report the use of an atmospheric pressure plasma in a dielectric-barrier discharge (DBD) configuration for exsolving nanoparticles (NPs) from within the oxide matrix. Usually, the exsolution of NPs in perovskites oxides follows a thermal-reduction process in the presence of hydrogen at temperatures higher than 800 oC for more than 12 h. Surprisingly, DBD treatments of perovskites oxides (La0.43Ca0.37Ni0.06Ti0.94O2.955, LCTNA-site deficient) resulted in the exsolution of NPs within few minutes at ambient-temperature even without the need for hydrogen. The changes in the size and distribution of NPs in He-fed DBD at 1.2 kV and at 1 kV are compared. Furthermore, the role of hydrogen-containing DBD on the nature of exsolution has also been studied and compared with pure He DBD. The DBD not only induces oxygen vacancies but also provides free electrons that are sufficient for driving the exsolution of NPs from an estimated exsolution depth ranging from 15-45 nm. Such exsolved NPs are firmly socketed within the oxide surface and hence induced excellent catalytic activities as discussed in this contribution. The concept of exsolution on a variety of perovskites oxides can be demonstrated with our DBD system that can even directly be applied for an in-situ energy application [1-8].
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