{"id":6205,"date":"2026-10-19T09:48:37","date_gmt":"2026-10-19T09:48:37","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsvorn-i-efnafraedi-bjorn-kirchhoff\/"},"modified":"2026-10-19T09:48:37","modified_gmt":"2026-10-19T09:48:37","slug":"doktorsvorn-i-efnafraedi-bjorn-kirchhoff","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsvorn-i-efnafraedi-bjorn-kirchhoff\/","title":{"rendered":"Doktorsv\u00f6rn \u00ed efnafr\u00e6\u00f0i – Bj\u00f6rn Kirchhoff"},"content":{"rendered":"
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Streymi<\/a><\/strong><\/p>\n

Doktorsefni:<\/strong>\u00a0Bj\u00f6rn Kirchhoff\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/p>\n

Heiti ritger\u00f0ar:<\/strong>\u00a0T\u00f6lvureikningar \u00e1 eiginleikum efnahvata fyrir afoxun s\u00farefnis (Computational Studies of Oxygen Reduction Catalysts)<\/p>\n

Andm\u00e6lendur:<\/strong>
<\/strong>Dr. Andrei Manolescu, pr\u00f3fessor vi\u00f0 Verkfr\u00e6\u00f0ideild H\u00e1sk\u00f3lans \u00ed Reykjav\u00edk,
Dr. Felix Studt, pr\u00f3fessor vi\u00f0 Institute for Chemical Technology and Polymer Chemistry (ITCP) og forst\u00f6\u00f0uma\u00f0ur Institute of Catalysis Research and Technology (IKFT) vi\u00f0 Karlsruhe Institute of Technology (KIT), \u00de\u00fdskalandi<\/p>\n

Lei\u00f0beinandi:<\/strong>\u00a0Dr. Hannes J\u00f3nsson, pr\u00f3fessor vi\u00f0 Raunv\u00edsindadeild H\u00e1sk\u00f3la \u00cdslands<\/p>\n

Einnig \u00ed doktorsnefnd:<\/strong> Dr. Egill Sk\u00falason, pr\u00f3fessor vi\u00f0 I\u00f0na\u00f0arverkfr\u00e6\u00f0i-, v\u00e9laverkfr\u00e6\u00f0i- og t\u00f6lvunarfr\u00e6\u00f0ideild\u00a0H\u00e1sk\u00f3la \u00cdslands
Dr. Timo Jacob, pr\u00f3fessor vi\u00f0 rafefnafr\u00e6\u00f0ideild Universit\u00e4t Ulm og yfirma\u00f0ur Helmholtz-Institute Ulm (HIU), \u00de\u00fdskalandi
Dr. Elvar \u00d6rn J\u00f3nsson, s\u00e9rfr\u00e6\u00f0ingur vi\u00f0 Raunv\u00edsindastofnun H\u00e1sk\u00f3lans.<\/p>\n

Doktorsv\u00f6rn st\u00fdrir:<\/strong>\u00a0Dr. Einar \u00d6rn Sveinbj\u00f6rnsson, pr\u00f3fessor og deildarforseti Raunv\u00edsindadeildar H\u00e1sk\u00f3la \u00cdslands<\/p>\n

\u00c1grip
<\/strong>Aukin virkni \u00ed afoxun s\u00farefnis \u00ed rafefnahv\u00f6rfum (oxygen reduction reaction, ORR) er mikilv\u00e6gur li\u00f0ur \u00ed \u00fer\u00f3un \u00e1 hagkv\u00e6mari og endingarbetri efnaraf\u00f6lum. T\u00f6lvureikninga er h\u00e6gt a\u00f0 nota til a\u00f0 hj\u00e1lpa til vi\u00f0 a\u00f0 skilja og sp\u00e1 fyrir um betri ORR-efnahvata. \u00cd \u00feessari ritger\u00f0 eru \u00fdmsar reiknia\u00f0fer\u00f0ir nota\u00f0ar, n\u00e1kv\u00e6mni \u00feeirra pr\u00f3fu\u00f0 og n\u00fdjar a\u00f0fer\u00f0ir \u00fer\u00f3a\u00f0ar \u00ed reikningum \u00e1 \u00fdmsum ORR-hv\u00f6tum. \u00cd fyrsta hluta ritger\u00f0arinnar er greint fr\u00e1 ranns\u00f3knum \u00e1 oxun plat\u00ednu-nan\u00f3klasa \u00fear sem ReaxFF-m\u00e6ttisfall er nota\u00f0, en \u00feetta er s\u00e1 hvati sem n\u00fa er mest nota\u00f0ur \u00ed efnaraf\u00f6lum. Reikningarnir byggja \u00e1 st\u00f3rkan\u00f3nsku Monte Carlo-a\u00f0fer\u00f0inni til a\u00f0 l\u00edkja eftir \u00fev\u00ed hvernig nan\u00f3agnirnar oxast og ey\u00f0ast. Fasagr\u00f6f fyrir rafefnaoxun eru sett fram og \u00feau s\u00fdna a\u00f0 st\u00f6\u00f0ug yfirbor\u00f0sox\u00ed\u00f0 geta myndast \u00feegar efnarafalar eru \u00ed notkun. Jafnframt er s\u00fdnt fram \u00e1 a\u00f0 klasar me\u00f0 samsetninguna Pt6O8 myndast einkum vi\u00f0 oxunina og \u00feannig er fengin at\u00f3mskalamynd af \u00fev\u00ed hva\u00f0 veldur hr\u00f6rnun plat\u00ednu-nan\u00f3klasanna.<\/p>\n

\u00cd \u00f6\u00f0rum hluta ritger\u00f0arinnar eru m\u00e1lmlausir ORR-hvatar rannsaka\u00f0ir, nefnilega nitur-\u00edb\u00e6tt graf\u00edn (N-doped graphene, NG). \u00dear eru reikningar bygg\u00f0ir \u00e1 \u00fe\u00e9ttnifellafr\u00e6\u00f0i rafeinda nota\u00f0ir til a\u00f0 meta varmafr\u00e6\u00f0ilega eiginleika mismunandi hvarfganga og meta yfirspennuna. \u00ddmsar n\u00e1lganir fyrir \u00fe\u00e9ttnifelli\u00f0 eru pr\u00f3fa\u00f0ar me\u00f0 samanbur\u00f0i vi\u00f0 Monte Carlo-rafeindareikninga \u00e1 \u00e1sogi og sveimi *O at\u00f3ms \u00e1 graf\u00edni, en \u00fea\u00f0 er mikilv\u00e6gt stig \u00ed ORR. Ni\u00f0urst\u00f6\u00f0urnar s\u00fdna a\u00f0 felli af GGA-ger\u00f0 eru ekki n\u00e6gjanlega n\u00e1kv\u00e6m en sum h\u00fdbr\u00ed\u00f0 felli og GGA-felli me\u00f0 sj\u00e1lfsv\u00edxlverkunarlei\u00f0r\u00e9ttingu gefa \u00fatkomu sem er \u00ed g\u00f3\u00f0u samr\u00e6mi vi\u00f0 Monte Carlo-reikningana. H\u00fdbr\u00ed\u00f0 felli er svo nota\u00f0 til a\u00f0 meta yfirspennuna fyrir \u00fdmsar ger\u00f0ir efnahvata. \u00datreiknu\u00f0 yfirspenna bendir til a\u00f0 efnahvatar af \u00feessari ger\u00f0 s\u00e9u ekki virkir, en \u00feegar lei\u00f0r\u00e9tt er fyrir v\u00edxlverkun vi\u00f0 vatnssameindir l\u00e6kkar \u00fatreiknu\u00f0 yfirspenna verulega. \u00deessi ni\u00f0ursta\u00f0a lei\u00f0ir til mikillar \u00e1skorunar \u00fev\u00ed kerfi \u00fear sem margar vatnssameindir eru einnig til sta\u00f0ar eru of st\u00f3r fyrir rafeindareikningana.<\/p>\n

\u00cd \u00feri\u00f0ja hluta ritger\u00f0arinnar er \u00fer\u00f3u\u00f0 n\u00fd a\u00f0fer\u00f0afr\u00e6\u00f0i sem gerir kleift a\u00f0 taka vatnsraflausn me\u00f0 \u00ed reikninginn. \u00dear er hluti kerfisins – hvatinn sem og sameindir sem hvarfast og n\u00e6rliggjandi vatnssameindir – tekinn me\u00f0 \u00ed rafeindareikningana \u00e1 me\u00f0an hinn hluti kerfisins, \u00fe.e. restin af raflausninni er l\u00fdst me\u00f0 m\u00e6ttisfalli. M\u00f6rkin milli sv\u00e6\u00f0anna tveggja eru valin \u00feannig a\u00f0 \u00feau liggja \u00ed gegnum lausnina til a\u00f0 gera \u00fea\u00f0 au\u00f0veldara a\u00f0 l\u00fdsa v\u00edxlverkuninni milli at\u00f3ma sitt hvorum megin vi\u00f0 skilin. \u00dear me\u00f0 ver\u00f0ur \u00e1skorunin s\u00fa a\u00f0 innlei\u00f0a skilin \u00feannig a\u00f0 at\u00f3m og sameindir fari ekki fr\u00e1 einu sv\u00e6\u00f0i yfir \u00ed anna\u00f0. N\u00fd a\u00f0fer\u00f0 sem bygg\u00f0 er \u00e1 endurvarpi fr\u00e1 skilfletinum og kallast SAFIRES er \u00fer\u00f3u\u00f0 \u00ed \u00feessum tilgangi. H\u00fan byggir \u00e1 eldri a\u00f0fer\u00f0 sem nefnd er FIRES. Me\u00f0 SAFIRES-a\u00f0fer\u00f0inni er skilfl\u00f6turinn milli sv\u00e6\u00f0anna f\u00e6ranlegur og finnur sj\u00e1lfkrafa r\u00e9ttan sta\u00f0, en agnir geta ekki f\u00e6rst \u00ed gegnum skilfl\u00f6tinn. S\u00fdnt er fram \u00e1 a\u00f0 me\u00f0 SAFIRES-a\u00f0fer\u00f0inni er orka, kraftar \u00e1 at\u00f3min og l\u00edkindadreifingin fyrir sta\u00f0setningu at\u00f3manna \u00ed g\u00f3\u00f0u samr\u00e6mi vi\u00f0 reikninga \u00fear sem enginn skilfl\u00f6tur er til sta\u00f0ar. \u00cd SAFIRES-a\u00f0fer\u00f0inni er t\u00edmaskrefi\u00f0 \u00ed reikningum \u00e1 t\u00edmaframvindu a\u00f0laga\u00f0 sj\u00e1lfkrafa til a\u00f0 finna \u00feann t\u00edmapunkt \u00fear sem \u00e1rekstur \u00e1 s\u00e9r sta\u00f0 vi\u00f0 skilfl\u00f6tinn og at\u00f3min endurvarpast fr\u00e1 skilfletinum \u00e1n orkubreytingar. N\u00fdtt reiknirit fyrir t\u00edmaframvinduna er innleitt me\u00f0 og \u00e1n tengingar vi\u00f0 hitaba\u00f0. \u00deetta er pr\u00f3fa\u00f0 me\u00f0 \u00fev\u00ed a\u00f0 reikna \u00fat Lennard-Jones v\u00f6kva, m\u00f3t v\u00f6kva og fastefnis Lennard-Jones at\u00f3ma og vatn \u00fear sem m\u00e6ttisf\u00f6ll l\u00fdsa v\u00edxlverkuninni. Me\u00f0 \u00feessari SAFIRES a\u00f0fer\u00f0 \u00e1samt n\u00fdlegri a\u00f0fer\u00f0 til a\u00f0 gera h\u00fdbr\u00ed\u00f0 reikninga me\u00f0 skautanlegum sameindum er lag\u00f0ur grunnurinn a\u00f0 lei\u00f0 til a\u00f0 taka vatnsraflausn me\u00f0 \u00ed reikninginn \u00ed kennilegum ranns\u00f3knum \u00e1 rafefnafr\u00e6\u00f0i \u00ed framt\u00ed\u00f0inni.<\/p>\n

Um doktorsefni\u00f0<\/strong><\/p>\n

Bj\u00f6rn Kirchhoff f\u00e6ddist 14. mars 1992 \u00ed Biberach \u00ed Baden-W\u00fcrttemberg, \u00de\u00fdskalandi. Hann er einkabarn Gudrunar Kirchhoff og J\u00f6rg Kirchhoff. Hann stunda\u00f0i n\u00e1m \u00ed efnafr\u00e6\u00f0i vi\u00f0 Universit\u00e4t Ulm, \u00fear sem hann lauk MSc. gr\u00e1\u00f0u \u00e1ri\u00f0 2017. A\u00f0 lokinni MS-gr\u00e1\u00f0u kom Bj\u00f6rn til \u00cdslands og h\u00f3f doktorsn\u00e1m undir handlei\u00f0slu Hannesar J\u00f3nssonar, pr\u00f3fessors vi\u00f0 Raunv\u00edsindadeild.<\/p>\n<\/div><\/div>","protected":false},"featured_media":4969,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_phd_date_start":"2021-05-28T13:00:00+00:00","_phd_date_end":"2021-05-28T15:00:00+00:00","_phd_location":"Askja Stofa 132","_phd_admission":"A\u00f0gangur \u00f3keypis","_phd_thesis_title":"T\u00f6lvureikningar \u00e1 eiginleikum efnahvata fyrir afoxun s\u00farefnis (Computational Studies of Oxygen Reduction Catalysts)","_phd_source_url":"https:\/\/gamli.hi.is\/vidburdir\/doktorsvorn_i_efnafraedi_bjorn_kirchhoff","_phd_source_node_id":"374863","_phd_source_type":"vidburdir","_phd_member_id":728,"footnotes":""},"phd_school":[101,93],"phd_discipline":[102],"class_list":["post-6205","phd_defence","type-phd_defence","status-publish","has-post-thumbnail","hentry","phd_school-raunvisindadeild","phd_school-verkfraedi-og-natturuvisindasvid","phd_discipline-phd-i-efnafraedi"],"_links":{"self":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_defence\/6205","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_defence"}],"about":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/types\/phd_defence"}],"version-history":[{"count":0,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_defence\/6205\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/media\/4969"}],"wp:attachment":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/media?parent=6205"}],"wp:term":[{"taxonomy":"phd_school","embeddable":true,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_school?post=6205"},{"taxonomy":"phd_discipline","embeddable":true,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_discipline?post=6205"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}