Publications

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2017
Figueira, J., J. Loureiro, J. Marques, C. Bianchi, P. Duarte, M. Ruoho, I. Tittonen, and I. Ferreira, "Optimization of Cuprous Oxides Thin Films to be used as Thermoelectric Touch Detectors", ACS Appl Mater Interfaces, vol. 9, issue 7, pp. 6520-6529, 2017. AbstractDOI

The electronic and optical properties of p-type copper oxides (CO) strongly depend on the production technique as it influences the obtained phases: cuprous oxide (Cu2O) or cupric oxide (CuO), the most common ones. Cu films deposited by thermal evaporation have been annealed in air atmosphere, with temperature between 225 and 375 °C and time between 1 and 4 h. The resultant CO films have been studied to understand the influence of processing parameters in the thermoelectric, electrical, optical, morphological, and structural properties. Films with a Cu2O single phase are formed when annealing at 225 °C, while CuO single phase films can be obtained at 375 °C. In between, both phases are obtained in proportions that depend on the film thickness and annealing time. The positive sign of the Seebeck coefficient (S), measured at room temperature (RT), confirms the p-type behavior of both oxides, showing values up to 1.2 mV·°C–1and conductivity up to 2.9 (Ω·m)−1. A simple detector using Cu2O have been fabricated and tested with fast finger touch events

Sousa, D. M., J. C. Lima, and I. Ferreira, "Synthesis of Cadmium Selenide Quantum Dots, Using 2, 2‐Bipyridine as a Capping and Phase Transfer Agent", ChemistrySelect, vol. 2, issue 3, pp. 1271-1274, 2017. AbstractDOI

Cadmium selenide quantum dots (CdSe QDs), were synthesized by one‐pot or water‐to‐organic phase transfer and capped with molten 2,2′‐bipyridine (bipy). The obtained CdSe QDs by the two‐step procedure, reveal average sizes of 2 nm while the one‐pot are mixed with secondary salt products and bipy and are undetectable by TEM. However the absorption peak of both CdSe QDs was at 425 nm and the emission band is centered at 535 nm, with a band width at half height of 77 nm, when excited with 425 nm light. The two‐step CdSe QDs synthesis has the great advantage of capping the CdSe QDs with bipy, forming a solid phase, which is easily stored and dispersed in most of the organic solvents. On the other hand, the one‐pot procedure requires an extra step to remove the secondary products.

Sulim, O., R. Ribeiro, I. Esteves, C. Antunes, A. Garate, P. Duarte, I. Ferreira, J. Mota, and M. Plaza, Design of structured adsorbents for aplications in gas adsorption processes - Conventional shaping vs 3D-Printed formulation, , 5-10 March, 2017. Abstract

Microporous materials highly activated and with potential to be used as adsorbents in many applications for gas
separation/purification are usually available as powders. These solids usually have a great and reversible gas
uptake, high gas selectivity, good chemical and thermal stability, but are unsuitable to be used in gas adsorption
processes, such as Pressure Swing Adsorption (PSA) or Simulated Moving Bed (SMB).
Zeolites, carbons and more recently metal-organic frameworks (MOFs) are examples of those materials. Their
use in adsorption-based processes are dependent of their upgrading from powders (micrometer scale) to
particles (pellets, spheres or granules at millimeter scale). This would overcome large pressure drops and
consequent energy consumptions when packing adsorbent columns in those processes. Thus, shaping
adsorbents is an important step to use them in industry, although it greatly affects their capacity and selectivity
towards a specific gas separation.
In this work, we explore techniques to shape powdered adsorbents, followed by their textural and mechanical
characterizations, and the study of their adsorption properties towards the main components of post-combustion
flues gases (CO2 and N2). Materials densification is proposed by employing two approaches:
- Conventional shaping through binderless mechanical compression and binder-containing extrusion; and
- Formulation by 3D printing (or additive manufacturing) to produce packed bed morphologies that
precisely replicate computer aided design (CAD) models.
Porous separation media are important for fluid-solid contacting in many unit operations, including adsorption.
Due to practical limitations, media particles are typically packed randomly into a column in a shaped form,
allowing fluid to flow through the interstitial voids. Key to the effectiveness of packed columns are the flowrelated properties of mass transfer, fluid distribution and dispersion, and back pressure, which in turn depend
upon packing geometry. Until now, no alternative was found to overcome this limitation and have optimal
ordered packing arrangements at the micron scale. 3D-Printing (or additive manufacturing) brings a wide range
of benefits that traditional methods of manufacturing or prototyping simply cannot. With this approach, complex
ordered geometries, that are not possible by conventional extrusion, can be designed and printed for a porous
media, being the equipment resolution the only limiting step to overcome.
The effect of parameters like compression force, particle sieving, binder nature, binder/adsorbent ratio were
firstly studied using conventional shaping techniques, as a basis for the consequent development of 3D-printed
formulations. The structured samples are then characterized and adsorption equilibria studies are performed on
them to evaluate their performance as media for gas adsorption separation processes. A volumetric/manometric
adsorption unit built in-house was used for this purpose. Relevant experimental data is obtained, which allows to
conclude that 3D-printed media can be an alternative porous media for application in gas adsorption processes.

2018
Ropio, I., A. C. Baptista, J. P. Nobre, J. Correia, F. Belo, S. Taborda, M. B. M. Faustino, J. P. Borges, A. Kovalenko, and I. Ferreira, "Cellulose paper functionalised with polypyrrole and poly(3,4-ethylenedioxythiophene) for paper battery electrodes", Org Electron, 2018. AbstractDOI

A simple process of commercial paper functionalisation via in situ polymerisation of conductive polymers onto cellulose fibres was investigated and applied as electrodes in paper-based batteries. The functionalisation involved polypyrrole (PPy) and Poly (3,4-ethylenedioxythiophene) (PEDOT) as conductive polymers with the process of functionalisation optimised for each polymer individually with respect to oxidant-to-monomer ratios and polymerisation times and temperature. Paper with conductivity values of 44 mS/cm was obtained by exposing the samples to pyrrole vapour for a period of 30 min at room temperature; however, polymerisation at temperatures of 40 °C lead to higher conductivity values to up 141 mS/cm. Consequently, functionalised PPy and PEDOT papers were applied as cathodes in batteries with Al foil anodes and commercial paper soaked in an electrolyte solution of NaCl.

Baptista, A. C., I. Ropio, B. Romba, J. P. Nobre, C. Henriques, J. C. Silva, J. I. Martins, J. P. Borges, and I. Ferreira, "Cellulose-based electrospun fibers functionalized with polypyrrole and polyaniline for fully organic batteries", J Mater Chem A, vol. 6, issue 1, pp. 256-265, 2018. AbstractDOI

A novel cellulose-based bio-battery made of electrospun fibers activated by biological fluids has been developed. This work reports a new concept for a fully organic bio-battery that takes advantage of the high surface to volume ratio achieved by an electrospun matrix composed of sub-micrometric fibers that acts simultaneously as the separator and the support of the electrodes. Polymer composites of polypyrrole (PPy) and polyaniline (PANI) with cellulose acetate (CA) electrospun matrix were produced by in situ chemical oxidation of pyrrole and aniline on the CA fibers. The structure (CA/PPy|CA|CA/PANI) generated a power density of 1.7 mW g−1 in the presence of simulated biological fluids, which is a new and significant contribution to the domain of medical batteries and fully organic devices for biomedical applications.

Faustino, B. M. M., D. Gomes, J. Faria, T. Juntunen, G. Gaspar, C. Bianchi, A. Almeida, A. C. Marques, I. Tittonen, and I. Ferreira, "CuI p-type thin films for highly transparent thermoelectric pn modules", Sci Rep, vol. 8, issue 1, pp. 6867-6867, 2018. AbstractDOI

Developments in thermoelectric (TE) transparent p-type materials are scarce and do not follow the trend of the corresponding n-type materials – a limitation of the current transparent thermoelectric devices. P-type thermoelectric thin films of CuI have been developed by three different methods in order to maximise optical transparency (>70% in the visible range), electrical (σ = 1.1 × 104 Sm−1) and thermoelectric properties (ZT = 0.22 at 300 K). These have been applied in the first planar fully transparent p-n type TE modules where gallium-doped zinc oxide (GZO) thin films were used as the n-type element and indium thin oxide (ITO) thin films as electrodes. A thorough study of power output in single elements and p-n modules electrically connected in series and thermally connected in parallel is inclosed. This configuration allows for a whole range of highly transparent thermoelectric applications.

Sousa, D. M., L. Cerqueira, A. Marques, G. Gaspar, J. C. Lima, and I. Ferreira, "Facile Microwave-assisted Synthesis Manganese Doped Zinc Sulfide Nanoparticles", Scientific Reports, vol. 8, pp. 15992, 2018.
2019
Marques, A. C., D. Miglietta, G. Gaspar, A. C. Baptista, A. Gaspar, A. Perdigão, I. Soares, C. Bianchi, D. Sousa, B. M. Morais Faustino, V. S. Amaral, T. Santos, A. P. Gonçalves, R. C. da Silva, F. Giorgis, and I. Ferreira, " Synthesis of thermoelectric magnesium-silicide pastes for 3D printing, electrospinning and low-pressure spray", Materials for Renewable and Sustainable Energy, pp. 8-21, 2019.
A.Rocha, D. Sousa, I. Ferreira, and M. S. Diniz, "Biochemical responses in Danio rerio following exposure to CdS and ZnS Quantum Dots", Annals of Medicine, vol. 51, pp. 71-71, 2019.
Cristovão, A. F., D. Sousa, F. Silvestre, I. Ropio, A. Gaspar, C. Henriques, A. Velhinho, A. C. Baptista, M. Faustino, and I. Ferreira, "Customized tracheal design using 3D printing of a polymer hydrogel: influence of UV laser cross-linking on mechanical properties", 3D Print Med, vol. 5, pp. 12, 2019.