Сборник статей - First virtual Bilateral Conference on Functional Materials (BiC-FM)

Acknowledgement.This work was supported by the Russian Science Foundation, grant 17-19-01787.

References:

[1] S.A. Evlashin, F.S. Fedorov, P.V. Dyakonov, Y.M. Maksimov, A.A. Pilevsky, K.I. Maslakov, Y.O. Kuzminova, Y.A. Mankelevich, E.N. Voronina, S.A. Dagesyan, V.A. Pletneva, A.A. Pavlov, M.A. Tarkhov, I.V. Trofimov, V.L. Zhdanov, N.V. Suetin, I.S. Akhatov, I. S., Role of Nitrogen and Oxygen in Capacitance Formation of Carbon Nanowalls. The Journal of Physical Chemistry Letters, 11(12), (2020).

Cristina Flox 1, Fatemeh Davodi 1, Davide Pavesi 2,3and Tanja Kallio 1

1 – Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, FI-00076, Espoo, Finland

2 – Avantium Chemicals BV, Zekeringstraat 29 1014 BV Amsterdam, The Netherlands

3 – Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA, Leiden, The Netherlands

cristina.flox@aalto.fi

Electrochemical CO 2reduction reaction is a key technology for the mitigation of the climate change. However, CO 2reduction is highly energetic and unfavourable electrochemical reaction, requiring catalyst to achieve economically appealing performance. In this scenario, Nickel-Nitrogen (Ni-N)-active sites within porous carbon are attracting increasing interest as inexpensive and efficient electrocatalyst of CO 2reduction. In fact, the Ni-N- active sites anchored to the carbon structures have been proposed as excellent solution for the conversion CO 2-to-CO, exceeding selectivity and partial current density values of the commercial electrocatalyst. Herein, the in-situ creation of Ni-N-active sites using Nickel Carbide nanoparticles-wrapped in a graphene shell (Ni 3C@graphene NPs) and Emeraldine as precursors in combination with the thermal treatments is evaluated. As a result, the Ni-N- active sites in combination with Ni 3C@graphene NPs provide a new paradigm, where the formate production is dominated leading a complete deactivation of CO route. Surprisingly, the unprecedent key performance indicators of the CO 2reduction showed a Faradaic Efficiency up to 90 % at 0.55V vs. RHE at 25ºC. Additionally, the CO 2-to-formate conversion showed a temperature sensitive- dependence, increasing the selectivity (up to 96 %) in the voltage range tested (0.45 to 0.7V vs. RHE), when the electrolysis was performed at 40ºC. The apparent Energy Activation values were calculated, attaining values up to 45 kJ mol -1at -0.55 V vs. RHE@40ºC, which agrees well with previous reports. Therefore, the creation of Ni-N- active sites in the Ni 3C@graphene NPs can effectively reduce the energy barrier towards the CO 2-to formate conversion, providing new mechanism insight for the CO 2reduction.

Cristina Floxreceived her PhD in Electrochemistry applied to flow reactors from Universitat de Barcelona in 2008, followed by postdoctoral fellowships in LEITAT and Catalonia Institute for Energy Research, Spain (2008–2017). Subsequently, she joined Aalto University in 2017, working on the design of innovative nanomaterials for energy applications. Particularly, she is focused on the development of electrodes for CO 2reduction and solid-electrolytes for lithium-ion batteries. Additionally, her research interest are fundamental aspects on energy storage systems, especially redox/semi-solid flow batteries, supercapacitors and Na-ion batteries. She published more than 47 refereed articles (h index 23, 2025 citations), 3 book chapters and 1 patent application.

Koskinen J 1.,Wester N 1., Etula J 1., Mynttinen E 2., Laurila T 2.

1Aalto University, School of Chemical Engineering, Espoo, Finland

2Aalto University, School of Electrical Engineering, Espoo, Finland

Jari.Koskinen@aalto.fi

Bio-sensing by applying electrochemical measurements offers several benefits in development of fast and simple devices. They have been investigated for detection of neural transmitters (e.g. dopamine) and recently for detection of drug molecules in blood samples. In this presentation the development of electrode materials made of thin amorphous carbon films and single wall carbon nanotube networks are reported. Layered structures prototype thin film sensors applying perm selective nafion top coatings are also demonstrated. Sensitivity and selectivity for bio-molecules detection in physiologically relevant concentrations has been demonstrated for analytes such as opioids and other analgesics together with most relevant interfering molecules.

Acknowledgement.This work was supported by Business Finland (FEDOC 211637 and FEPOD 2117731 projects), Aalto CHEM Doctoral School and Orion Research Foundation Sr for funding. The authors acknowledge the provision of facilities by Aalto University OtaNano−Micronova Nanofabrication Center and Aalto University Raw materials Infrastructure.

Prof. Jari Koskinenis professor of Materials Science at Aalto University, School Chemical Engineering. He has an experience of over 35 years in the field of surface engineering and in particular on development of carbon nanomaterials and coatings. He has over 180 international publications of the topic. He is leading a research group: “Physical properties surfaces and interfaces”. The main impact of his research in material science are in the field of tribology and currently in electrochemical bio-sensing. Currently he is head of the Department of Chemistry and Materials Science. His H-index is 28.

Trussov I. A. 1, Nazarov E. E. 1, Aksyonov D. A. 1, Fedotov S. S. 1

1 – Skolkovo Institute of Science and Technology, Moscow, Russia

s.fedotov@skoltech.ru

LiFePO 4is a commercialized cathode material ensuring wide applications of Li-ion battery technology for stationary energy storage and renewable energy sources. Regardless of the obvious simplicity of its crystal structure and chemical composition, LiFePO 4holds astonishing defects chemistry arising from the rearrangement of cations and vacancies within tetrahedral and octahedral sites, variations in their occupancies and iron oxidation state. It was demonstrated that so-called “Li-rich” phases might form with the Li excess being located at the Fe sites reaching up to 10 %. At the same time the polyanion sublattice was rarely considered defective. It was taken for granted that the PO 4group is highly durable, with no defects being possible at the P site.

In this talk, we will concentrate upon various old and new defect peculiarities in LiFePO 4and its Li-rich counterpart studied by combined X-ray and neutron diffraction methods coupled with high-throughput DFT and MD calculations. The recently discovered cations arrangements and off-stoichiometry in LiFePO 4due to a partial replacement of Fe with Li atoms or PO 4with hydroxyl groups for hydrothermally prepared samples at different synthesis conditions will be discussed. Such off-stoichiometries can reach over 10 % yielding Li 1+xFe 1-xPO 4(x ≤ 0.1) and Li 1-xFe 1+x(PO 4) 1-y(OH) 4y(x ≤ 0.05, y ≤ 0.1) solid solutions respectively. Both Li and OH-substitutions trigger essential changes in the crystal structure and properties, increasing the migration barriers for Li ions and affect the electrochemical performance. We demonstrated that the off-stoichiometry significantly depends on the precursors and reducing agent concentrations and the order of mixing thereof, rendering them critical parameters that control the defects formation of the hydrothermally synthesized LiFePO 4-based cathode materials.