Kitabı oku: «First virtual Bilateral Conference on Functional Materials (BiC-FM)», sayfa 3

Positronium emission from materials for Li-ion batteries

Bernardo Barbiellini^1,2*, Jan Kuriplach³

¹School of Engineering Science, LUT university, Lappeenranta 53851, Finland

²Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA

³Department of Low Temperature Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, CZ-180 00 Prague, Czech Republic

bernardo.barbiellini@lut.fi

A positron and an electron annihilate into gamma-ray photons but before this annihilation, the positron and an electron can bind together to form a positronium (Ps). Mono-energetic positron beams can be used to bombard materials and to probe their atomistic properties. In particular, the implanted positron can diffuse back to the surface of a solid and be emitted as Ps with a range of kinetic energies that provides key information regarding the energy levels of the electrons in the material. These energies can be measured by time of flight (TOF) experiments, but the Ps lifetime before annihilation has been too short for precise measurements. Recently, Jones et al. [1], by exciting the emitted Ps with a laser to greatly increase its lifetime, obtained TOF measurements with an ultimate precision of the order of 5 meV that will allow materials simulations in systems pertinent for Li-ion batteries cathodes [2,3].

References:

[1] A. C. L. Jones, H. J. Rutbeck-Goldman, T. H. Hisakado, A. M. Piñeiro, H. W. K. Tom, A. P. Mills, Jr. B. Barbiellini, J. Kuriplach, Phys. Rev. Lett. 117, 216402 (2016)

[2] B. Barbiellini, J. Kuriplach, Journal of Physics: Conf. Series 791, 012016 (2017)

[3] J. Kuriplach, A. Pulkkinen, B. Barbiellini, Condensed Matter 4, 80 (2019)

The role of nitrogen and oxygen in the formation capacity of carbon materials

Evlashin S.A.^1,*, Fedorov F.S.¹, Dyakonov P.V. ^1,2, Maksimov Yu.M.², Pilevsky A.A.², Maslakov K.I.², Akhatov I.Sh.¹

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

2 – Lomonosov Moscow State University, Moscow, Russia

s.evlashin@skoltech.ru

Carbon materials are attracting increasing attention as a material for supercapcitor fabrication due to availability and high specific surface area. However, the initial capacitance of raw carbon is quite low, so the N and O heteroatoms are introduced in order to increase their specific capacitance. Despite the vast amount of studies on carbon materials, a lot of grey areas in mechanisms that lead to the increase in the specific capacitance remain. We demonstrate an effective method for modification of the surface of Carbon NanoWalls (CNWs) using DC plasma in atmospheres of O₂, N₂, and their mixture. Processing in the plasma leads to the incorporation of ∼4 atom % nitrogen and ∼10 atom % oxygen atoms. Electrochemical measurements reveal that CNWs functionalized with oxygen groups are characterized by higher capacitance. The specific capacitance for samples with oxygen reaches 8.9 F cm^-3 at a scan rate of 20 mV s^-1. In contrast, the nitrogen-doped samples demonstrate a specific capacitance of 4.4 F cm^-3 at the same scan rate. The mechanism of heteroatom incorporation into the carbon lattice is explained using density functional theory calculations.

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).

Nickel-Nitrogen active sites towards selective High-rate CO₂-to-formate electroreduction

Cristina Flox¹, Fatemeh Davodi¹, Davide Pavesi^2,3 and Tanja Kallio¹

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 CO₂ reduction reaction is a key technology for the mitigation of the climate change. However, CO₂ reduction 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 CO₂ reduction. In fact, the Ni-N- active sites anchored to the carbon structures have been proposed as excellent solution for the conversion CO₂-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 (Ni₃C@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 Ni₃C@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 CO₂ reduction showed a Faradaic Efficiency up to 90 % at 0.55V vs. RHE at 25ºC. Additionally, the CO₂-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^-1 at -0.55 V vs. RHE@40ºC, which agrees well with previous reports. Therefore, the creation of Ni-N- active sites in the Ni₃C@graphene NPs can effectively reduce the energy barrier towards the CO₂-to formate conversion, providing new mechanism insight for the CO₂ reduction.

Cristina Flox received 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 CO₂ reduction 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.

Development of materials for electrochemical bio-sensing

Koskinen J¹., Wester N¹., Etula J¹., Mynttinen E²., Laurila T².

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 Koskinen is 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.

Defects in olivine-type cathode materials for Li-ion batteries

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

LiFePO₄ is 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, LiFePO₄ holds 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 PO₄ group 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 LiFePO₄ and 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 LiFePO₄ due to a partial replacement of Fe with Li atoms or PO₄ with 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-xPO₄ (x ≤ 0.1) and Li_1-xFe_1+x(PO₄)_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 LiFePO₄-based cathode materials.

More data on the crystal structure and properties of Li-rich LiFePO₄ and OH-substituted LiFePO₄ as well as the interrelation between “new” and “old” defects in synthetic phosphates and natural olivine-type minerals will be presented and analyzed.

Acknowledgement.This work was supported by the Russian Foundation for Basic Research, grant 18-29-12097.

Ceramic fuel cell fabrication trend from conventional methods to digital printing

Muhammad Imran Asghar^1,2, Peter D. Lund¹

New Energy Technologies Group, Department of Applied Physics, Aalto University School of Science, P. O. Box 15100, FI-00076 Aalto, Espoo, Finland.

Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, China.

imran.asghar@aalto.fi

Ceramic fuel cell, a.k.a. solid oxide fuel cell, has been emerging as a clean energy technology [1–3]. Researchers of the fuel cell community have been reporting promising electrode and electrolyte materials for the fuel cell since many decades. Many researchers reported fabrication of their cells using power-press methods [4,5]. Although this method is good for the small-scale research studies, this method is not suitable for large-scale upscaling of the technology. The current state-of-the-art ceramic fuel cells are manufactured using tape-casting and screen-printing techniques. Other techniques such as pulse laser deposition, spraying techniques, atomic layer deposition, physical and chemical vapor deposition methods, have been reported as well. Recently, the fabrication of ceramic fuel cell fabrication have been reported using ink-jet and 3D printing techniques. These low-cost printing techniques could solve many issues faced by the promising fuel cell technology. In this study, an overview on the trend of the ceramic fuel cell fabrication and their effects on the cell performance and stability will be presented. The key challenges related to the conventional and 3D fabrication will be highlighted in the work.

Figure 1: up) Traditional 3-layer ceramic nanocomposite fuel cell; down) so called “single-layer” ceramic fuel cell.

Acknowledgement.This work is supported by Academy of Finland (Grant No. 13329016). Dr. Asghar thanks Academy of Finland (Grant No. 13322738) and the Hubei overseas Talent 100 program for their support.

References

[1] M. I. Asghar, M. Heikkilä and P. D. Lund, Materials Today Energy, 5 (2017) 338.

[2] M. I. Asghar, S. Jouttijärvi and P. D. Lund, International Journal of Hydrogen energy, 43 (2018) 12892.

[3] M. I. Asghar, S. Jouttijärvi and P. D. Lund, International Journal of Hydrogen energy, 43 (2018) 12797.

[4] M. I. Asghar, S. Jouttijärvi, R. Jokiranta, A. Valtavirta and P. D. Lund, Nanoenergy, 53 (2018) 391.

[5] M. I. Asghar, S. Jouttijärvi, R. Jokiranta, E. Hochreiner and P. D. Lund, International Journal of Hydrogen Energy, (2019).

Friday, October 9

Oral Sessions

Day 2, Octorber 9

Session 4: Photonics of functional materials I Chairs: N. Gippius/ D. Kopylova

10.00–10.25

Keynote Talk 9 Prof. Zhipei Sun

Nonlinear Optics with Nanomaterials

10.25–10.50

Keynote Talk 10 Dr. Yury Gladush

Aerosol synthesized carbon nanotube thin films for nonlinear optical applications

10.50–11.05

Oral Talk 9 Dr. Aleksei Emelianov

Individual SWCNT Transistor with Photosensitive Planar Junction Induced by Two-Photon Oxidation

11.05–11.20

Oral Talk 10 Dr. Dmitry Mitin

Strategies to optimize the optoelectronic performance of patterned single-walled carbon nanotube layers

11.20–11.45

Break

Flash presentations Chair: A. Nasibulin

11.45–13.20

Flash oral presentations (3 min)

13.20–14.40

Break/lunch time

Session 4: Photonics of functional materials II Chairs: Yu. Svirko/ E. Khabushev

14.40–15.05

Keynote Talk 11 Prof. Elena Obraztsova

Graphene for laser applications

15.05–15.30

Keynote Talk 16 Prof. Sergey Makarov

Functional Halide Perovskite Nanostructures

15.30–15.45

Oral Talk 11 Dr. Bakhysh Bairamov

Nanophotonic molecular engineering of functional quantum dots and biomedical structures

15.45–16.00

Oral Talk 12 Dr. Dmitry Chermoshentsev

Dimensional confinement and waveguide effect of Dyakonov surface waves in twisted confined media

16.00–16.25

Break

Session 4: Modification/functionalization of functional materials

Chairs: V. Mordkovich/ A. Goldt

16.25–16.50

Keynote Talk 13 Prof. Polina Kuzhir

Macro-, Micro- and Nano-Roughness of Carbon-Based Interface with the Living Cells: Towards a Versatile Bio-Sensing Platform

16.50–17.15

Keynote Talk 14 Prof. Ayrat Dimiev

Polymer composites, comprising single-atomic-layer graphenic inclusions. Preparation, structure and properties.

17.15–17.30

Oral Talk 13 Prof. Boris Gorshunov

H₂O molecule in nano-space

17.30–17.45

Oral Talk 14 Prof. Markus Ahlskog

Surface characteristics control the attachment and functionality of (chimeric) avidin

17.45

Closing remarks

Nonlinear Optics with Nanomaterials

Zhipei Sun^1,2

1. Department of Electronics and Nanoengineering, Aalto University, Finland

2. QTF Centre of Excellence, Department of Applied Physics, Aalto University, Finland

zhipei.sun@aalto.fi

In this talk, I will discuss our recent results on nonlinear optics with one-dimensional (e.g., carbon nanotubes and nanowires [1]) and two-dimensional layered (e.g., graphene [2–3], transition metal dichalcogenides [3–5], and black phosphorus [6–7]) materials. These results show advantages of utilizing low-dimensional nanomaterials for various photonic and optoelectronic applications, such as high-purity quantum emitters [1], wavelength converters [2–5], and actively [8] and passively [2,6,7] mode-locked ultrafast lasers. Further, I will present our recent advances employing hybrid structures, such as two-dimensional heterostructures [2], plasmonic structures [8-10], and silicon/fibre waveguides integrated structures [8-10].

Acknowledgement.This work was supported by Business Finland (APhotonics), Academy of Finland, Academy of Finland Flagship Programme (PREIN), the European Union's Horizon 2020 research and innovation program (S2QUIP), and ERC (Grant No. 834742).

References:

[1] K. F. Lee et.al., Adv. Mater. 29, 1605978 (2017)

[2] Z. Sun, Nat. Photon. 12, 383 (2018).

[3] F. Bonaccorso, Z. Sun, Opt. Mater. Exp.4,63(2014).

[4] A. Säynätjoki et al., Nat. Commun. 8, 893(2017).

[5] L. Karvonen etal., Nat. Comm. 8,15714(2017).

[6] D. Li, et al., Sci. Rep. 5, 15899 (2015).

[7] H. Yang, et al., ACS Photonics, 4, 3023 (2017).

[8] J. Bogusławski, et al., Adv. Funct. Mater. 28, 1801539 (2018);

[9] H. Hu et al., Nat. Comm. 10, 1131 (2019).

[10] A. Autere et al., Adv. Mater. 30, 1705963 (2018).

[11] K. Chen et al., Nat. Photon. 13, 754 (2019).

Zhipei Sun is Professor of Photonics and the head of the Photonics Research Group at the Department of Electronics and Nanoengineering of Aalto University, Finland. He earned his PhD from Institute of Physics, Chinese Academy of Sciences, in 2005. Currently, he is actively involved with European quantum flagship, Academy of Finland Photonics Flagship and Academy of Finland Centre on quantum technology projects. Recently, he received a European Research Council Advanced Grant for his work on nanomaterials based photonics. His research interests include nonlinear optics, nanophotonics, and ultrafast photonics. In particular, he focuses on carbon nanotubes, graphene, and other two-dimensional layered materials for photonics and optoelectronics.

Aerosol synthesized carbon nanotube thin films for nonlinear optical applications

Yuriy Gladush,¹ Aram Mkrtchyan,¹ Diana Galiakhmetova,¹ Georgy Ermolaev,² Eldar Khabushev,¹ Dmitry Krasnikov,¹ Albert Nasibulin¹

¹Skolkovo Institute of Science and Technology, Nobel St. 3, Moscow, Russia

²Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia

Y.Gladush@skoltech.ru

Single walled carbon nanotubes (SWCNTs) are known to demonstrate high third order optical nonlinearity. Applications in this field requires high power illumination which may cause damage of SWCNT thin film. In the presentation we discuss the application of aerosol synthesized SWCNTs for short pulse generation in the fiber lasers with emphasis on the stability of the SWCNT saturable absorber. We compare the PVA/SWCNT composites and polymer-free SWCNTs and demonstrate that different types of saturable absorber implementation result in different mechanisms of degradation. This investigation provides a root for a stable and efficient saturable absorber for a short pulse generation. In the second part of the talk we discuss the carbon nanotubes nonlinear properties in evanescent field interaction geometry when carbon nanotubes are deposited on top of the waveguide. We demonstrate that we can control the nonlinear response of the SWCNT saturable absorber by electrochemical gating and switch pulse generation regimes in the fiber laser. Finally, we discuss other nonlinear optical effects with carbon nanotubes.

Acknowledgement. This work was supported by a grant of Russian Science Foundation (No. 17-19-01787).

Yuriy Gladush is a senior research scientist in Laboratory of Nanomaterials of Skoltech. His research area is optics and laser physics. In Nanomaterials lab Yuriy is responsible for projects related to optical properties of carbon nanotubes and other nanomaterials and its application for fiber laser ultrashort pulse generation, photoresponce, etc. Prior to Skoltech Yuriy was working in Institute of spectroscopy where his research was dedicated to resonance energy transfer in organic/inorganic semiconductor hybrid structures. His PhD, obtained in the same institute, was related to theoretical investigation of nonlinear wave phenomena in Bose-Einstein condensates and optics.