Trial lecture
March 1st, 10:15 AM, Seminar room Avogadro, Chemistry building
Trial lecture title:
«Perspectives of inorganic nanoparticles for biomedical applications”.
Kreeringssammendrag/Conferral summary
Ammoniakk er en svært viktig forbindelse innenfor kjemisk industri og som alternativt drivstoff innen det grønne skiftet, men er dog en svært forurensende gass å slippe ut. Vi har undersøkt Pt-Rh nanopartikler og filmer som modellkatalysatorer for NH3 oksidasjon, for å minimere utslipp av NH3 gjennom spesifikk katalytisk konvertering til N2. For dette kreves tilgang til veldefinerte nanopartikler gjennom syntese, og in situ / operando eksperiementer hvor man kan analysere stabiliteten til katalysatorene under relevante operasjonelle betingelser, som er det dette arbeidet har gått ut på.
Main research findings
Ammonia (NH3) is critical in the production of fertilizers and is one of the main alternatives to substitute fossil marine fuels, however it is a highly polluting gas. We investigated Pt-Rh nanoparticles and thin films as model catalysts for oxidation of NH3 to minimize emissions by converting it into harmless N2. The bimetallic Pt-Rh nanoparticles demonstrated improved catalytic activity over monometallic Rh and enhanced N2 selectivity compared to monometallic Pt nanoparticles. Supporting operando studies on Pt-Rh films at lower oxygen pressure revealed the importance of the pressure gap on product selectivities in such fundamental studies.
Access to well-defined nanoparticles is key in catalytic studies as it enables correlation between the nanoparticle characteristics and the resulting properties. We developed nanoparticle synthesis approaches controlling key factors like metal distribution, Pt-Rh chemical composition, and nanoparticle size, all crucial for the catalyst's performance.
We also used advanced in situ electron microscopy to study the nanoparticles' thermal stability in vacuum, finding that Pt and Rh mixing or segregating depends on temperature and size. While vacuum conditions offer insights into mixing or segregation behaviors, they are not necessarily representative of realistic operational conditions. Hence, we also studied the Pt-Rh nanoparticles and films in oxidizing environments, observing migration of Rh to the surface. This result helped us to conclude on the optimal configuration of the second-generation Pt-Rh nanoparticle catalyst for the NH3 oxidation reaction.
Candidate contact information
Email: martin.jensen@kjemi.uio.no
Tel. +47 954 44 642