Sirvi Autor "Nerut, Jaak" järgi

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Electroreduction of hexacyanoferrate(III) anion on cadmium (0001) single crystal electrode
(2007-06-11T07:57:27Z) Nerut, Jaak
Hapniku redutseerimise uurimine plaatina nanoosakestel, mis on sadestatud turbast sünteesitud süsinikkandjale
(Tartu Ülikool, 2021) Lobjakas, Wiljar; Kasuk, Heili; Nerut, Jaak; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Keemia instituut
Käesolevas töös uuriti hapniku redutseerimise reaktsiooni (ORR) Pt nanoosakestel, mis on sadestatud turbast sünteesitud süsinikalusmaterjalile kolme erineva meetodiga – kasutades redutseerijana NaBH4, etüleenglükooli või isopropüülalkoholi. Uuritavate materjalide füüsikaliseks karakteriseerimiseks teostati N2 sorptsioonianalüüs, röntgenstruktuurianalüüs ja termogravimeetriline analüüs. Elektrokeemiliseks karakteriseerimiseks mõõdeti materjalide elektrokeemiliselt aktiivne pindala (ECA) kolmeelektroodse süsteemiga 0,1 M HClO4 lahuses ja prootonvahetusmembraaniga kütuseelemendi (PEMFC) ühikrakus. Materjalide ORR-i kineetikat uuriti pöörleva ketaselektroodi meetodiga. PEMFC ühikrakus uuriti materjalide aktiivsust. Tulemustena leiti, et mida suurem on materjali ECA, seda suurem on ka katalüütiline aktiivsus. Võrreldes kommertsiaalse materjaliga (60% Pt on HSA Ketjenblack) on töös uuritud materjalid vähem aktiivsed.
Metanooli oksüdeerimine aerogeelist sünteesitud süsinikule sadestatud plaatina-praseodüümoksiid nanokatalüsaatoril 0,5 M väävelhappelahuses
(Tartu Ülikool, 2021) Prits, Alise-Valentine; Kasuk, Heili; Nerut, Jaak; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Keemia instituut
Töös uuriti, mil määral sobib aerogeelist sünteesitud süsinikule sadestatud plaatina-praseodüümoksiidi nanokatalüsaator kasutamiseks metanooli kütuseelementides. Materjali uuriti füüsikaliste karakteriseerimise meetoditega (röntgendifraktsioonanalüüs, eripinnamõõtmised, termogravimeetriline analüüs) ja elektrokeemiliste uurimismeetoditega (tsükliline voltamperomeetria, kronoamperomeetria). Leiti, et materjalil on head omadused metanooli oksüdeerimiseks ja seda oleks võimalik kasutada katalüsaatormaterjalina metanooli kütuseelementides. Materjali omadused metanooli oksüdeerimiseks olid paremad kui kommertsiaalsel materjalil, ent samas kehvemad kui mõningatel kirjanduse ülevaates kirjeldatud teistel sarnastel materjalidel.
Oxygen reduction on platinum nanoparticles deposited onto chromium carbide-derived carbon support
(Tartu Ülikool, 2019) Nguyen, Huy Qui Vinh; Kasuk, Heili; Nerut, Jaak; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
Polymer electrolyte membrane fuel cells are very promising energy conversion devices, which have already found application in public transportation. However, one of the obstacles in the even wider application is the sluggishness of oxygen reduction reaction (ORR) at the cathode. Therefore, there is room for development in the field of catalysis synthesis. This study aimed to develop novel carbon support material for the platinum catalyst and to study ORR on the new catalyst. The carbon supports were synthesized from chromium carbide using chlorination at various temperatures (800-900°C). The platinum nanoparticles were deposited onto the chromium carbide-derived carbon supports by two different methods. Thermogravimetric analysis, X-ray diffraction and low-temperature nitrogen adsorption/desorption methods were used to characterize the structure of catalyst and catalyst support. ORR was studied with cyclic voltammetry and rotating disk electrode methods. The catalysts showed high activity towards ORR in 0.1 M HClO4 solution.
Photoelectrocatalytic Hydrogen Generation at Photocathode Based on Silicon Nanowires Grown from Alternative Seeds
(Tartu Ülikool, 2024) Olli, Paul Erik; Nerut, Jaak; Chenevier, Pascale; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Keemia instituut
The aim of the study was to explore alternative growth seeds to gold nanoparticles for the synthesis of silicon nanowires (SiNWs), characterise the SiNWs grown from alternative seeds, create a water splitting photocathode based on SiNWs, and evaluate the photoelectrocatalytic performance of the photocathode. Quantum dots were synthesised and used as alternative seeds for the SiNWs, which were grown on an amorphous carbon substrate. Scanning electron microscopy estabished the sizes and shapes of the nanowires. Every constituent metal of quantum dots was attributed to a specific morphological characteristic of the nanowires. The kinetics of SiNW growth on alternative seeds was evaluated. Catalyst electrodeposition proved the be the best catalyst application method. Photocathode with SiNWs from alternative seeds was found to be inferior to the photocathode with SiNWs grown from gold nanoparticles. Alternative growth seeds proved to be suitable and of interest for growing SiNWs.
Plaatina katalüsaatori süntees kasutades degradeerunud kütuseelemendist taastoodetud plaatinat ja selle elektrokeemiline karakteriseerimine kütuseelemendis
(Tartu Ülikool, 2023) Palusalu, Andres; Jäger, Rutha; Nerut, Jaak; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Keemia instituut
Prootonvahetusmembraaniga kütuseelemendid (PEMFCd) leiavad üha laialdasemat kasutust, mistõttu muutub aina olulisemaks nende taaskasutamine. Kuna PEMFC sisaldab suures koguses Pt, mis on haruldane ja kallis väärismetall, osutub kütuseelemendi komponendi, membraanelektroodsüsteemi (MEA), ümbertöötlemine ülioluliseks. Töös uuriti erinevaid võimalusi kasutusea lõpetanud MEAdest plaatina eraldamiseks ning selle kasutamist uue katalüsaatormaterjali ja seejärel uue MEA valmistamiseks. Saadud uusi katalüsaatormaterjale karakteriseeriti erinevate füüsikaliste uurimismeetoditega ning teostati PEMFC ühikraku mõõtmised. Tööst selgus, et sünteesitud katalüsaatormaterjalist valmistatud PEMFC ühikrakus saavutati maksimaalne võimsustihedus 0,95 W cm−2 ning Pt elektrokeemiliselt aktiivne pindala 40,3 mPt2g−1 .
Platinum catalysts deposited onto peat-derived carbon for oxygen reduction reaction in a proton-exchange membrane fuel cell
(Tartu Ülikool, 2023) Lobjakas, Wiljar; Nerut, Jaak; Kasuk, Heili; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Keemia instituut
The aim of this thesis was to investigate the oxygen reduction reaction on platinum catalysts deposited onto peat-derived carbon. Catalyst materials were synthesised using several different methods. Physical characterisation of the materials was carried out through particle size measurements, N2 sorption analysis, X-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Electrochemical characterisation was done by measuring the electrochemically active surface area of the materials using a three-electrode system in 0.1 M HClO4 solution and a proton-exchange membrane fuel cell (PEMFC) single cell. The ORR kinetics of the materials were investigated using a rotating disc electrode method. The activity of the materials was also tested in a PEMFC single cell. The obtained data were compared with the results of a commercial catalyst material (60% Pt on Ketjenblack EC-300J).
Synthesis and characterisation of oxide catalyst for oxygen evolution reaction in alkaline media
(Tartu Ülikool, 2023) Prits, Alise-Valentine; Küngas, Rainer; Nerut, Jaak; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Keemia instituut
The properties and suitability for catalysing the oxygen evolution reaction in alkaline media were studied for four oxide catalyst materials with the perovskite structure. The structure of the materials was studied by X-ray diffraction analysis, scanning electron microscopy with energydispersive X-ray spectroscopy. Two materials were studied in a three-electrode measurement set-up. Ten electrodes were prepared by coating Ni mesh with precursor solution of an oxide catalyst. Electrodes were characterised by scanning electron microscopy with energy-dispersive X-ray spectroscopy. The electrochemical activity of the electrodes was studied in a twoelectrode set-up in conditions similar to the operating conditions of an alkaline water electrolyser. Results demonstrated that catalyst coating improved the catalytic activity of the substrate, resulting in activity similar to a commercial precious metal electrode.