Browsing by Author "Maloney, Thaddeus C."

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Highly Porous Willow Wood-Derived Activated Carbon for High-Performance Supercapacitor Electrodes
(2019-11-05) Phiri, Josphat; Dou, Jinze; Vuorinen, Tapani; Gane, Patrick A.C.; Maloney, Thaddeus C.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In this study, we present willow wood as a new low-cost, renewable, and sustainable biomass source for the production of a highly porous activated carbon for application in energy storage devices. The obtained activated carbon showed favorable features required for excellent electrochemical performance such as high surface area (∼2 800 m2 g-1) and pore volume (1.45 cm3 g-1), with coexistence of micropores and mesopores. This carbon material was tested as an electrode for supercapacitor application and showed a high specific capacitance of 394 F g-1 at a current density of 1 A g-1 and good cycling stability, retaining ∼94% capacitance after 5000 cycles (at a current density of 5 A g-1) in 6 M KOH electrolyte. The prepared carbon material also showed an excellent rate performance in a symmetrical two-electrode full cell configuration using 1 M Na2SO4 electrolyte, in a high working voltage of 1.8 V. The maximum energy density and power density of the fabricated symmetric cell reach 23 W h kg-1 and 10 000 W kg-1, respectively. These results demonstrate that willow wood can serve as a low-cost carbon feedstock for production of high-performance electrode material for supercapacitors.
Mapping Nanocellulose- and Alginate-Based Photosynthetic Cell Factory Scaffolds : Interlinking Porosity, Wet Strength, and Gas Exchange
(2023-08-14) Levä, Tuukka; Rissanen, Ville; Nikkanen, Lauri; Siitonen, Vilja; Heilala, Maria; Phiri, Josphat; Maloney, Thaddeus C.; Kosourov, Sergey; Allahverdiyeva, Yagut; Mäkelä, Mikko; Tammelin, Tekla
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
To develop efficient solid-state photosynthetic cell factories for sustainable chemical production, we present an interdisciplinary experimental toolbox to investigate and interlink the structure, operative stability, and gas transfer properties of alginate- and nanocellulose-based hydrogel matrices with entrapped wild-type Synechocystis PCC 6803 cyanobacteria. We created a rheological map based on the mechanical performance of the hydrogel matrices. The results highlighted the importance of Ca2+-cross-linking and showed that nanocellulose matrices possess higher yield properties, and alginate matrices possess higher rest properties. We observed higher porosity for nanocellulose-based matrices in a water-swollen state via calorimetric thermoporosimetry and scanning electron microscopy imaging. Finally, by pioneering a gas flux analysis via membrane-inlet mass spectrometry for entrapped cells, we observed that the porosity and rigidity of the matrices are connected to their gas exchange rates over time. Overall, these findings link the dynamic properties of the life-sustaining matrix to the performance of the immobilized cells in tailored solid-state photosynthetic cell factories.
Production of functionalized nanocelluloses from different sources using deep eutectic solvents and their applications
(2023-09-01) Almeida, Ricardo O.; Maloney, Thaddeus C.; Gamelas, José A.F.
A2 Katsausartikkeli tieteellisessä aikakauslehdessä
Nanocelluloses have gained increasing attention over the years due to their attractive intrinsic properties, such as high strength and stiffness, high biocompatibility, good film-forming ability, easy surface functionalization, tunable optical properties, etc. With these unique features, nanocelluloses have the potential to be applied in a wide range of applications. However, the economic and environmental problems associated to the conventional methods of producing nanocelluloses make it difficult to produce them on a large scale. Therefore, the scientific community has been studying new alternatives. One alternative that has recently emerged is the use of deep eutectic solvents (DESs) for the production of nanocelluloses. The biodegradable and biocompatible character of the DESs combined with their low toxicity, easy preparation, tunability and recyclability turn them promising alternatives for the nanocellulose isolation. In this sense, this article provides a comprehensive overview of the production of (ligno)cellulose nanofibrils ((L)CNFs) and (ligno)cellulose nanocrystals ((L)CNCs) from woody resources and non-woody/agricultural residues using DESs. Additionally, the applications of the produced DES-(L)CNFs and DES-(L)CNCs are also discussed. From this review, it was possible to conclude that by using different DES components, different types of surface chemical functionalization on the (L)CNFs are obtained, which confer to the final material distinct properties. Additionally, films produced from the DES-(L)CNFs showed very good mechanical properties. On the other hand, the DES-(L)CNCs can be produced with higher yields and showing better thermal stability compared to the conventional methods of CNC production. Despite the promising results, an in-depth economic analysis on the use of DES for nanocellulose production is still lacking. Notwithstanding, favorable DES recyclability and reuse results indicate that they are good candidates for the nanocellulose (and nanocellulose-based films) production in a large scale.