Maike Käärik

Dr. Maike Käärik


Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 March 2018 in ChemElectroChem
Verified
Journal Article
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SRSander Ratso
Sander Ratso
MKMaike Käärik
Maike Käärik
MKMati Kook
Mati Kook
PPPäärn Paiste
Päärn Paiste
VKVambola Kisand
Vambola Kisand
Kaido TammeveskiKaido Tammeveski
Kaido Tammeveski

28 May 2018 in ChemElectroChem
Verified
Journal Article
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KKKaarel Kisand
Kaarel Kisand
ASAve Sarapuu
Ave Sarapuu
APAnna-Liisa Peikolainen
Anna-Liisa Peikolainen
HSHelina Seemen
Helina Seemen
MKMati Kook
Mati Kook
Kaido TammeveskiKaido Tammeveski
Kaido Tammeveski

20 October 2023 in Molecules
Verified
Journal Article
Open access
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MKMaike Käärik
Maike Käärik
MAMati Arulepp
Mati Arulepp
APAnti Perkson
Anti Perkson
JLJaan Leis
Jaan Leis
This study investigates three carbide-derived carbon (CDC) materials (TiC, NbC, and Mo2C) characterized by uni-, bi-, and tri-modal pore sizes, respectively, for energy storage in both neat and acetonitrile-diluted 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. A distribution of micro- and mesopores was studied through low-temperature N2 and CO2 adsorption. To elucidate the relationships between porosity and the electrochemical properties of carbon materials, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy measurements were conducted using three-electrode test cells. The ultramicroporous TiC-derived carbon is characterized by a high packing density of 0.85 g cm−3, resulting in superior cathodic and anodic capacitances for both neat ionic liquid (IL) and a 1.9 M IL/acetonitrile electrolyte (93.6 and 75.8 F cm−3, respectively, in the dilute IL). However, the bi-modal pore-sized microporous NbC-derived carbon, with slightly lower cathodic and anodic capacitances (i.e., 85.0 and 73.7 F cm−3 in the dilute IL, respectively), has a lower pore resistance, making it more suitable for real-world applications. A symmetric two-electrode capacitor incorporating microporous CDC-NbC electrodes revealed an acceptable cycle life. After 10,000 cycles, the cell retained approximately 75% of its original capacitance, while the equivalent series resistance (ESR) only increased by 13%.

20 July 2023 in Materials
Verified
Journal Article
Open access
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YKYogesh Kumar
Yogesh Kumar
SASrinu Akula
Srinu Akula
EKElo Kibena-Põldsepp
Elo Kibena-Põldsepp
MKMaike Käärik
Maike Käärik
JKJekaterina Kozlova
Jekaterina Kozlova
Kaido TammeveskiKaido Tammeveski
Kaido Tammeveski
Rechargeable zinc-air batteries (RZAB) have gained significant attention as potential energy storage devices due to their high energy density, cost-effectiveness, and to the fact that they are environmentally safe. However, the practical implementation of RZABs has been impeded by challenges such as sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), including poor cyclability. Herein, we report the preparation of cobalt- and nitrogen-doped porous carbon derived from phloroglucinol-formaldehyde polymer networks with 2-methyl imidazole and cobalt phthalocyanine as precursors for nitrogen and cobalt. The CoN-PC-2 catalyst prepared in this study exhibits commendable electrocatalytic activity for both ORR and OER, evidenced by a half-wave potential of 0.81 V and Ej=10 of 1.70 V. Moreover, the catalyst demonstrates outstanding performance in zinc-air batteries, achieving a peak power density of 158 mW cm−2 and displaying excellent stability during charge-discharge cycles. The findings from this study aim to provide valuable insights and guidelines for further research and the development of hierarchical micro-mesoporous carbon materials from polymer networks, facilitating their potential commercialisation and widespread deployment in energy storage applications.

20 May 2022 in Catalysts
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Journal Article
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KVKaidi Veske
Kaidi Veske
ASAve Sarapuu
Ave Sarapuu
MKMaike Käärik
Maike Käärik
AKArvo Kikas
Arvo Kikas
VKVambola Kisand
Vambola Kisand
Kaido TammeveskiKaido Tammeveski
Kaido Tammeveski
The development of non-precious metal electrocatalysts towards oxygen reduction reaction (ORR) is crucial for the commercialisation of polymer electrolyte fuel cells. In this work, cobalt-containing nitrogen-doped porous carbon materials were prepared by a pyrolysis of mixtures of saccharides, cobalt nitrate and dicyandiamide, which acts as a precursor for reactive carbon nitride template and a nitrogen source. The rotating disk electrode (RDE) experiments in 0.1 M KOH solution showed that the glucose-derived material with optimised cobalt content had excellent ORR activity, which was comparable to that of 20 wt% Pt/C catalyst. In addition, the catalyst exhibited high tolerance to methanol, good stability in short-time potential cycling test and low peroxide yield. The materials derived from xylan, xylose and cyclodextrin displayed similar activities, indicating that various saccharides can be used as inexpensive and sustainable precursors to synthesise active catalyst materials for anion exchange membrane fuel cells.

7 June 2024 in Nanomaterials
Verified
Journal Article
Open access
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MLMadis Lüsi
Madis Lüsi
HEHeiki Erikson
Heiki Erikson
MKMaike Käärik
Maike Käärik
HPHelle-Mai Piirsoo
Helle-Mai Piirsoo
JAJaan Aruväli
Jaan Aruväli
Kaido TammeveskiKaido Tammeveski
Kaido Tammeveski
We explored two methods for synthesizing Pd nanoparticles using three different carbide-derived carbon (CDC) support materials, one of which was nitrogen-doped. These materials were studied for oxygen reduction reaction (ORR) in 0.1 M KOH solution, and the resulting CDC/Pd catalysts were characterized using TEM, XRD, and XPS. The citrate method and the polyol method using polyvinylpyrrolidone (PVP) as a capping agent were employed to elucidate the impact of the support material on the final catalyst. The N-doping of the CDC material resulted in smaller Pd nanoparticles, but only in the case of the citrate method. This suggests that the influence of support is weaker when using the polyol method. The citrate method with CDC1, which is predominantly microporous, led to a higher degree of agglomeration and formation of larger particles in comparison to supports, which possessed a higher degree of mesoporosity. We achieved smaller Pd particle sizes using citrate and NaBH4 compared to the ethylene glycol PVP method. Pd deposited on CDC2 and CDC3 supports showed similar specific activity (SA), suggesting that the N-doping did not significantly influence the ORR process. The highest SA value was observed for CDC1/Pd_Cit, which could be attributed to the formation of larger Pd particles and agglomerates.