This thesis consists of fourteen original articles listed below. The articles are referred in the text by Roman numerals I–XIV.
I S. Ratso, I. Kruusenberg, M. Vikkisk, U. Joost, E. Shulga, I. Kink, T. Kallio, K. Tammeveski, Highly active nitrogen-doped few-layer graphene/ carbon nanotube composite electrocatalyst for oxygen reduction reaction in alkaline media, Carbon 73 (2014) 361–370.
II I. Kruusenberg, S. Ratso, M. Vikkisk, P. Kanninen, T. Kallio, A.M. Kannan, K. Tammeveski, Highly active nitrogen-doped nanocarbon electrocatalysts for alkaline direct methanol fuel cell, Journal of Power Sources 281 (2015) 94–102.
III S. Ratso, I. Kruusenberg, U. Joost, R. Saar, K. Tammeveski, Enhanced oxygen reduction reaction activity of nitrogen-doped graphene/multi-walled carbon nanotube catalysts in alkaline media, International Journal of Hydrogen Energy 41 (2016) 22510–22519.
IV I. Kruusenberg, D. Ramani, S. Ratso, U. Joost, R. Saar, P. Rauwel, A.M. Kannan, K. Tammeveski, Cobalt-nitrogen co-doped carbon nanotube cathode catalyst for alkaline membrane fuel cells, ChemElectroChem 3 (2016) 1455–1465.
V S. Ratso, I. Kruusenberg, A. Sarapuu, P. Rauwel, R. Saar, U. Joost, J. Aru-väli, P. Kanninen, T. Kallio, K. Tammeveski, Enhanced oxygen reduction reaction activity of iron-containing nitrogen-doped carbon nanotubes for alkaline direct methanol fuel cell application, Journal of Power Sources 332 (2016) 129–138.
VI S. Ratso, I. Kruusenberg, A. Sarapuu, M. Kook, P. Rauwel, R. Saar, J. Aruväli, K. Tammeveski, Electrocatalysis of oxygen reduction on iron- and cobalt-containing nitrogen-doped carbon nanotubes in acid media, Electrochimica Acta 218 (2016) 303–310.
VII S. Ratso, I. Kruusenberg, M. Käärik, M. Kook, R. Saar, M. Pärs, J. Leis, K. Tammeveski, Highly efficient nitrogen-doped carbide-derived carbon materials for oxygen reduction reaction in alkaline media, Carbon 113 (2017) 159–169.
VIII S. Ratso, I. Kruusenberg, M. Käärik, M. Kook, R. Saar, P. Kanninen, T. Kallio, J. Leis, K. Tammeveski, Transition metal-nitrogen co-doped carbide-derived carbon catalysts for oxygen reduction reaction in alkaline direct methanol fuel cell, Applied Catalysis B: Environmental 219 (2017) 276–286.
IX S. Ratso, I. Kruusenberg, M. Käärik, M. Kook, L. Puust, R. Saar, J. Leis, K. Tammeveski, Highly efficient transition metal and nitrogen co-doped carbide-derived carbon electrocatalysts for anion exchange membrane fuel cells, Journal of Power Sources 375 (2018) 233–243.
X S. Ratso, M. Käärik, M. Kook, P. Paiste, V. Kisand, S. Vlassov, J. Leis, K. Tammeveski, Iron and nitrogen co-doped carbide-derived carbon and carbon nanotube composite catalysts for oxygen reduction reaction, ChemElectroChem 5 (2018) 1827–1836.
XI S. Ratso, N. Ranjbar Sahraie, M.T. Sougrati, M. Käärik, M. Kook, R. Saar, P. Paiste, Q. Jia, J. Leis, S. Mukerjee, F. Jaouen, K. Tammeveski, Synthesis of highly-active Fe-N-C catalysts for PEMFC with carbide-derived carbons, Journal of Materials Chemistry A 6 (2018) 14663–14674.
XII S. Ratso, M. Käärik, M. Kook, P. Paiste, J. Aruväli, S. Vlassov, V. Kisand, J. Leis, A.M. Kannan, K. Tammeveski, High performance catalysts based on Fe/N co-doped carbide-derived carbon and carbon nanotube composites for oxygen reduction reaction in acid media, International Journal Hydrogen Energy 44 (2019) 12636–12648.
XIII S. Ratso, M.T. Sougrati, M. Käärik, M. Merisalu, M. Rähn, V. Kisand, A. Kikas, P. Paiste, J. Leis, V. Sammelselg, F. Jaouen, K. Tammeveski, Effect of ball-milling on the oxygen reduction reaction activity of iron and nitrogen co-doped carbide-derived carbon catalysts in acid media, ACS Applied Energy Materials 2 (2019) 7952–7962.
XIV S. Ratso, A. Zitolo, M. Käärik, M. Merisalu, M. Rähn, A. Kikas, V. Kisand, P. Paiste, J. Leis, V. Sammelselg, S. Holdcroft, F. Jaouen, K. Tammeveski, Non-precious metal cathodes for anion exchange membrane fuel cells from ball-milled iron and nitrogen doped carbide-derived carbons (Renewable Energy, accepted).
Author’s contribution
Paper I The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretations of electrochemical testing results.
Paper II The author was responsible for the synthesis of graphene-carbon nanotube composites, performed all electrochemical measurements with that catalyst and data analysis. The author participated in the writing of the manuscript.
Paper III The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of electrochemical testing results and primarily responsible for writing the manuscript.
Paper IV The author was responsible for the synthesis of catalysts, performed
Paper V The author was responsible for the synthesis of catalysts, performed all electrochemical measurements except fuel cell testing and data analysis. The author is responsible for the interpretations of electro-chemical testing results and participated in writing the manuscript.
Paper VI The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of electrochemical testing results and participated in writing the manuscript.
Paper VII The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of all testing results and primarily responsible for writing the manuscript.
Paper VIII The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of all testing results and primarily responsible for writing the manuscript.
Paper IX The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of all testing results and primarily responsible for writing the manuscript.
Paper X The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of all testing results and primarily responsible for writing the manuscript.
Paper XI The author was responsible for the synthesis of catalysts, performed all electrochemical measurements, X-ray diffraction measurements and data analysis. The author is responsible for the interpretation of all testing results excluding Mössbauer spectroscopy and X-ray absorption spectroscopy and is primarily responsible for writing the manuscript.
Paper XII The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of all testing results and primarily responsible for writing the manuscript.
Paper XIII The author was responsible for the synthesis of catalysts, performed all electrochemical measurements, X-ray diffraction measurements, N2 adsorption measurements and data analysis. The author is responsible for the interpretation of all testing results excluding Mössbauer spectroscopy and is primarily responsible for writing the manuscript.
Paper XIV The author was responsible for the synthesis of catalysts, performed all electrochemical measurements and data analysis. The author is responsible for the interpretation of all testing results excluding X-ray absorption spectroscopy and is primarily responsible for writing the manuscript.