Sergii has obtained his PhD in Physical Chemistry in 2015 from L.V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of Ukraine, focusing on structure, sensor and electrophysical properties of tin oxide nanocomposites [25, 26, 27, 28, 29] (publications numbers here and below in this section from the list in CV CIÊNCIAVITAE). During PhD work, he also participated in several projects, dealing with investigating the functional properties of zeolites [30] and nanocomposites based on porous SiC [22, 23]. In 2007-2013 he was involved in a collaborative project with Pillar JSC company (manufacturer of silicon wafers for solar cells). The ideas proposed by Sergii resulted in the development of silicon waste recycling technology [24]. This was the first experience of the work in an industrial environment during the early-stage career. After completing the PhD, Sergii contributed to the research in various groups. In 2015-2016 he was a post-doc at Nazarbayev University, Republic of Kazakhstan, Astana, and took part in the research project in the area of SERS sensors [21]. In 2016 he obtained a grant for young scientists at the National University of Science and Technology (MISiS), Russia, Moscow, and participated in several projects focused on different topics. One project was aimed at the development of novel doped CeO2-based electrolytes for solid oxide fuel cells [18]. He also supervised a MSc thesis within the scope of this work. Another project was developed in collaboration with the department of porous substances and materials of L.V. Pisarzhevskii Institute of Physical Chemistry NAS of Ukraine. This project was focused on the investigation of the catalytic properties of ordered porous SiC materials [22] and graphitic carbon nitride (g-C3N4) [17]. Since 2019 Sergii is a contracted researcher at University of Aveiro, CICECO - Aveiro Institute of Materials, Portugal. Research activities are mainly related to the synthesis and characterization of MXene-based materials as electrocatalysts for hydrogen evolution, electrodes for supercapacitors and photocatalysts. This is a new direction of the CICECO research, started with Sergii´s fellowship within the SusPhotoSolutions, a big national (PT) project focusing on materials and approaches for sustainable photovoltaics and photocatalytic processes, two thematic papers were recently published: [9] Sergiienko, S. A., et al. "MXene-containing composite electrodes for hydrogen evolution: Material design aspects and approaches for electrode fabrication." Int. J. of Hydrogen Energy 46.21 (2021): 11636-11651; [5] Sergiienko, S. A. et al. "Photocatalytic removal of benzene over Ti3C2Tx MXene and TiO2-MXene composite materials under solar and NIR irradiation". J of Mat. Chem. C (2022). The project proposed by candidate (similar theme) received a positive assessment in Marie Sklodowska-Curie Actions (MSCA) Horizon Europe 2022. Since 2019 Sergii also contributed to the development of thermoelectric materials [1, 10, 12, 13], photocatalysts for hydrogen evolution and structural characterization of g-C3N4 [3, 14, 17], catalysts for aqueous ethanol conversion into 1,3-butadiene [4, 11]. Contributions to structural characterization of various materials [2, 6, 7, 8, 16] (publications numbers here and below in this section from the list in CV CIÊNCIAVITAE). In summary, during last 5 years, Sergii has participated in 6 projects, including 2 projects with industrial collaboration and presented 4 oral presentations at international conferences. Within this period, he published 17 papers in SCI journals, including 2 as the first and corresponding author. From these, 10 papers were published in top quartile Q1, and 7 papers in quartile Q2 journals in the areas of Materials Science, Physical Chemistry, Environmental Sciences, Energy and Fuels and Physics: Atomic, Molecular and Chemical. One patent application was submitted.