Carbon Group Oral Communications

Barium titanate piezoelectric flexible materials enabled by hierarchically porous graphite for application as mechanical energy harvesters and sensors

Mariana Rodriguesa , Artur Baetaa , Maxim Ivanova , Yifei Liub , Donglei Fanc , Paula M. Vilarinhoa , Paula Ferreiraa

aDepartment of Materials and Ceramic Engineering, CICECO – Aveiro Institute of Material, University of Aveiro, 3810-193 Aveiro, Portugal. bMaterials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712, USA. cDepartment of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712, USA. E-mail: pcferreira@ua.pt

Wearable sensors are becoming increasingly important in off-site monitoring. In this context, the development of piezoelectric flexible materials turned to be urgent. In this work, multi-level porous graphite is used as support for the synthesis of BaTiO3. Nanostructured BaTiO3 has been growth by “bottom-up” approach within the pores of graphite foams. Hydrothermal colloidal suspensions and sol gel solutions are being impregnated in three dimensional foams. In the case of the hydrothermal colloidal suspension, the impregnation was carried out with (VA) and without (NV) voltage assistance (V = ± 0,5 V).The composite was treated to 400 °C to hydroxyl groups and water and to enable a second impregnation step to fulfil the pores. The sol gel solutions were left in contact with the foam till all solution was absorbed. After, rapid thermal annealing and microwave-assisted furnace heat treatments were performed to crystallize tetragonal BaTiO3. In both cases, mainly tetragonal barium titanate was achieved as confirmed by XRD and Raman. High-resolution SEM imaging was performed to understand the structural and morphological features in relation to the synthesis conditions. Evaluation of piezoelectric and electric properties of these fabricated nanostructures was carried out and will be discussed.

Graphite foam BaTiO3

Impregnatedgraphite foam with BaTiO3 Figure 1. SEM micrographs of graphite, barium titanate nanoparticles and impregnated foam.

Acknowledgments: This work was developed within the scope of the project CICECO Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020 and in the scope of the Piezoflex Project UTA-EXPL/NPN/0015/2019, financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. PF is thankful to FCT for the IF/00300/201.5.

Nanorange thickness graphite films: growth, transfer and applications

Geetanjali Deokara , Alessandro Genoveseb , Ulrich Buttnerb , Venkatesh Singaravelub , Pedro M. F. J. Costaa

aKing Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division, Thuwal 23955‐6900, Saudi Arabia. bKAUST, Core Labs, Thuwal 23955‐6900, Saudi Arabia. E-mail: pedro.dacosta@kaust.edu.sa

Flexi-transparent conducting films are a likely critical component of next-generation smart devices such as miniaturized portable gas sensors.1,2 To this end, graphene and other layered materials have been extensively investigated as nanoscaled conductive films.3,4 Here, we report nanorange thickness graphite films (NGF), produced via chemical vapour deposition, and their characteristics. We achieved fast growth of NGF (thickness of ~100 nm) on both sides of a Ni foil (~55 cm2). 5 By cross-section transmission electron microscopy, we identified local thickness variations in the NGF and correlated those with the metal foil grain characteristics and surface topography. 5 On a macro-scale (i.e. mm2), the NGF film appears uniform - with a few hundred highly-ordered graphene layers (d0002 ~0.335 nm), epitaxially grown on Ni {111} planes. When studied at smaller scales (i.e. ≤µm2), few-layer graphene regions were found (with a density of 0.1–3.0% over 100 µm2). Unlike graphene, 6-8 the NGF can be easily transferred onto a desired substrate, without polymer support. 9 Amongst other things, we demonstrate that NGF has good electrical conductivity (2000 S/cm, sheet resistance 10-50 Ω/sq) and it is semi-transparent (~60% in the range 300-800 nm).

Figure 1. Schematics for the transfer and storage of NGF. The front-side (FS-NGF) and back-side (BS-NGF) films can be detached without the use of a polymer support.

References

[1] Nag, A.; Mitra, A.; Mukhopadhyay, S.C.; Sensors Actuat A – Phys, 2018, 270, 177-194. [2] Spruit, R.G.; van Omme, J.T.; Ghatkesar, M.K.; Garza, H.H.P.; J. Microelectromech., 2017, S26, 1165-1182. [3] Doscher, H.; Schmaltz, T.; Neef, C.; Thielmann, A.; Reiss, T.; 2D Mater., 2021, 8, 022005. [4] Novoselov, K.S.; Fal'ko, V.I.; Colombo, L.; Gellert, P.R.; Schwab, M.G.; Kim, K.; Nature, 2012, 490, 192-200. [5] Deokar, G.; Genovese,A.;Costa,P.M.F.J.; Nanotechnology, 2020, 31, 485605.[6] Deokar, G.; Avila, J.; Razado-Colambo, I.; Codron, J.L.; Boyaval, C.; Galopin, E.; Asensio, M.C.; Vignaud, D.; Carbon, 2015, 89, 82-92. [7] Deokar, G.; Codron, J.-L.; Boyaval, C.; Wallart, X.; Vignaud, D.; 4th Graphene Conference (Toulouse, France), 2014, communication. [8] Wei, W.; Deokar, G.; Belhaj, M.; Mele, D.; Pallecchi, E.; Pichonat, E.; Vignaud, D.; Happy, H.; Proceedings of the 44th European Microwave Conference (EUMC), 2014, 367-370. [9] Deokar, G.; Genovese, A.; Surya, S.G.; Long, C.; Salama, K.N.; Costa, P.M.F.J.; Sci. Rep., 2020, 10, 18931.

Acknowledgments: Thanks are due to KAUST for funding (BAS/1/1346-01-01) and the Core Labs for the use of facilities.

Valorization of agro-forestry biomass residues into ethylene glycol

Lucília S. Ribeiro, José J.M. Órfão, M. Fernando R. Pereira

Laboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials (LSRE-LCM), Faculty of Engineering of the University of Porto, Porto, Portugal. E-mail: lucilia@fe.up.pt

The development of an efficient and environmentally friendly process for biomass catalytic production into diols is highly required due to the increasing demand for ethylene glycol (EG), monomer of many polyester polymers.1-3 Therefore, this work focused on the green direct catalytic conversion of forestry and agricultural lignocellulosic wastes into EG. In a previous work, a mixture of W and Ru catalysts supported on oxidized carbon nanotubes was found to lead to higher EG production, since the modified support contributes to a high surface area acid structure that favors the initial step of cellulose hydrolysis to glucose and suppresses further glucose isomerization to fructose.4 Following the same approach, that catalytic mixture was evaluated in the one-pot hydrolytic hydrogenation of the different waste lignocellulosic materials listed in Figure 1. 5 In standard tests, 300 mL of water, 750 mg of ball-milled substrate and 300 mg of each catalyst were introduced into a 1000 mL stainless steel reactor under stirring at 150 rpm. After heating under N2 to 205 ºC, the reaction was initiated by switching to H2 (50 bar), and the reaction mixture was analyzed by high performance liquid chromatography (HPLC) and total organic carbon (TOC). The properties of the materials were characterized by several techniques. Figure 1 shows the results of waste materials conversion and EG yields after 5 h calculated based on the total amount of biomass and the holocellulose content. All kinds of biomass materials (softwood, hardwood, herbaceous, etc.) could be converted into ethylene glycol and other polyols. Depending on the lignocellulosic material, the EG yield based on the total amount of biomass varied between 0.8 and 25.2 %. The highest EG yields were obtained for cotton wool and tissue paper, since these materials are practically composed of cellulose. In general, the woody materials allow obtaining higher EG yields than the herbaceous materials. Apart from the different composition, the structure of the various biomass samples also played an important role in the production of EG.

Figure 1. Catalytic results of waste biomass materials conversion to EG.

References

[1] Ruppert, A.M.; Weinberg, K.; Palkovits, R.; Angew. Chem. Int. Ed., 2012, 51, 2564-2601. [2] Kobayashi, H.; Yamakoshi, Y.; Hosaka, Y.; Yabushita, M.; Fukuoka, A.; Catal. Today, 2014, 226, 204-209. [3] Wataniyakul, P.; Boonnoun, P.; Quitain, A.T.; Sasaki, M.; Laosiripojana, N.; Shotipruk, A.; Catal. Commun., 2018, 104, 41-47. [4] Ribeiro, L.S.; Órfão, J.J.M.; Pereira, M.F.R.; Bioresour. Technol., 2018, 263, 402-409. [5] Ribeiro, L.S.; Órfão, J.J.M.; Pereira, M.F.R.; Ind. Crops Prod., 2021, 166, 113461.

Acknowledgments: This work was financially supported by: Base-UIDB/50020/2020 and ProgrammaticUIDP/50020/2020 Funding of LSRE-LCM, funded by national funds through FCT/MCTES (PIDDAC).

Development of porous carbon materials from agro-industrial waste derived from olive oil production

Ana P. Ferreira da Silvaa, Sadenova Aknurb, Assem Shinibekovab , Marzhan S. Kalmakhanovab , Bakytgul K. Massalimovab, Helder T. Gomesa, Jose L. Diaz de Tuestaa

aCentro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal. bTaraz Regional University named after M.Kh.Dulaty, Department of Chemistry and Chemical Engineering, Taraz, Kazakhstan. E-mail: anapaula.silva@ipb.pt

The European Union is the largest producer, consumer and exporter of olive oil around the world. 1 Consequently, olive pomace (OP), a by-product of olive oil production, is generated in great amounts, presenting several environmental impacts on the ecosystem when untreated. Despite being a serious environmental problem, OP represent nowadays a precious resource of useful compounds for recovery and valorization purposes. 2 One valorization alternative is the development of biochars, carbon-based materials produced via pyrolysis of biomass. Biochars can be further activated by physical, chemical or physicochemical methods, developing great porosity that provides high adsorptive capacity for wastewater treatment. 3 In this study, biochars and activated carbons (ACs) were developed from OP through pyrolysis and activation by hydrothermal route, impregnation with H3PO4, and CO2 injection, resulting in the samples biochar, AC-HTC, AC-H3PO4 and AC-CO2, respectively. In the production of AC-HTC, 4 g of OP was first placed in digestion vessels with 30 mL of distilled water. Then, the hydrothermal treatment of the biomass was conducted for 3 h at 230 ºC and 370 autogenous pressures. AC-H3PO4 was prepared by acid impregnation with 100 mL of 85% H3PO4 per 5 g of OP at 150 ºC for 3 h. The solids recovered from the hydrothermal treatment and acid impregnation were pyrolyzed in a tube furnace under N2 atmosphere at 800 ºC for 4 h. For activation with CO2, OP was first pyrolyzed under N2 atmosphere, then CO2 was injected into the furnace at 800 ºC for 1 h. In Table 1 are shown the burn-off and porosity values obtained from the produced materials. As observed, the activation process with CO2 allows developing the materials with the highest BET surface area and total pore volume, suitable properties to consider them in wastewater treatment applications.

Table 1. Burn-off after pyrolysis and textural properties of the developed biochar and ACs.

Sample

mass loss (%)

Biochar 74.0

BET surface area (m2 g -1)

14

Total pore volume (mm3 g -1)

14

AC-HTC 71.7 183 AC- H3PO4

AC-CO2 81.7 208 86.3 473 137 123 276

References

[1] European Commission; Olive Oil, 2021 https://ec.europa.eu/info/food-farming-fisheries/plants-and-plantproducts/plant-products/olive-oil_en#oliveoilintheeu. [2] Puig-Gamero, M.; Esteban-Arranz, A.; SanchezSilva, L.; Sánchez, P., J. Environ. Chem. Eng., 2021, 9,105374. [3] Diaz de Tuesta, J. L.; et al.; J. Environ. Chem. Eng., 2021, 9, 105004.

Acknowledgments: This work was funded by the Bagaço+Valor project – Clean technology for the valorization of the byproduct of the olive pomace in the oil extracting industry. (NORTE-01-0247-FEDER-072124), co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).

Cobalt and iron phthalocyanine-doped carbon nanotubes as bifunctional oxygen electrocatalysts

Rafael G. Moraisa, Natalia Rey-Raapa,b , José Luís Figueiredoa, M. Fernando R. Pereiraa

aLSRE-LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, R. Dr. Roberto Frias s/n, 4200-465 Porto, Portugal. bDepartment of Physical and Analytical Chemistry, Oviedo University-CINN, 33006, Oviedo, Spain. E-mail: rgm@fe.up.pt

Nowadays, the optimization of a single system that combines storage and conversion devices is crucial to achieve maximum energy efficiency. The unitized regenerative fuel cell (URFC) combines both an electrolyzer (energy storage) and a fuel cell (energy conversion), and can achieve high energy efficiencies using environmentally friendly approaches. 1 Nonetheless, the oxygen reactions of the URFC, oxygen evolution and reduction reactions (OER and ORR, respectively), present sluggish kinetics which hinder the overall performance of the device. Therefore, the development of highly efficient, widely available and low-cost carbon materials using non-noble metals is essential to achieve a competitive technology capable of replacing the current Pt and Ru benchmark catalysts. In this study, iron and cobalt phthalocyanines (FePc and CoPc, respectively) were incorporated on carbon nanotubes (CNT). The resulting monometallic samples were mixed using different ratios to obtain a bifunctional oxygen electrocatalyst. The incorporation of these metal macrocycles led to enhanced performances towards both oxygen reactions, although two different interactions were observed. In the OER, there was a synergy between both macrocycles, sample 1:1 FePc:CoPc (mass ratio) being the electrocatalyst with the highest electrochemical performance. Contrarily, during the ORR, a competing effect took place between both active centers. Regarding bifunctionality, the bimetallic sample with a 1:1 FePc:CoPc mass ratio exhibited the lowest potential gap between the OER and ORR (0.80 V), demonstrating its great potential as a bifunctional oxygen electrocatalyst.

Scheme 1. LSVs of monometallic and 1:1 mass ratio bimetallic electrocatalysts.

References

[1] Morais, R.G.; Rey-Raap. N.; Figueiredo, J.L.; Pereira, M.F.R.; Appl. Surf. Sci., 2022, 572, 151459.

Acknowledgments: This work was financially supported by Project "UniRCell" - POCI-01-0145-FEDER-016422 - funded by European Structural and Investment Funds (FEEI) through - Programa Operacional Competitividade e Internacionalização - COMPETE2020 and by national funds through FCT - Fundação para a Ciência e a Tecnologia, I.P., Project “BiCat4Energy” with reference PTDC/EQU-EQU/1707/2020, Base (UIDB/50020/2020) and Programmatic (UIDP/50020/2020) Funding of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), and PDEQB (PD9989). RGM acknowledges the Research Grant from FCT (2020.06422.BD). The authors are indebted to CEMUP for assistance with XPS and SEM analyses.

Ni on carbon electrocatalysts for gas-phase CO2 methanation

Liliana P. L. Gonçalvesa,b, Alexey Serovc, Geoffrey McCoold, Mikaela Dicomed, Juliana P. S. Sousaa, O. Salomé G. P. Soaresb, Oleksandr Bondarchuka, Dmitri Y. Petrovykha, Oleg I. Lebedeve, M. Fernando R. Pereirab, Yury V. Kolen’koa

aInternational Iberian Nanotechnology Laboratory (INL), 4715-330 Braga, Portugal. bLSRE-LCM, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal. cOak Ridge National Laboratory, Oak Ridge, TN, USA. dPajarito Powder, LLC., Albuquerque, NM USA. eLaboratoire CRISMAT, UMR 6508, CNRS-ENSICAEN, Caen 14050, France. E-mail: liliana.goncalves@inl.int

The similarity between heterogeneous catalysis and electrocatalysis can be observed in the fact that both processes involve sequences of bond breaking and formation; however, the interchangeability in the use of the materials for both processes is not common. 1 Ni-based electrocatalysts supported on carbon materials are cost-effective materials with good catalytic performance; thus, they present a good option to be used in gas phase heterogeneous catalysis. 2 In this work, the performance of commercially available Ni/C, NiMo/C and NiRe/C electrocatalysts as heterogeneous catalysts for CO2 methanation was evaluated. Figure 1a presents the CO2 conversion (XCO2) and CH4 selectivity (SCH4) on the catalysts. It is possible to observe that the monometallic Ni/C material demonstrates the best CO2 methanation performance, with XCO2 = 83% and SCH4 = 99.7% at 400 °C. Furthermore, this sample exhibits intact performance during 90 h of time-on-stream testing (Figure 1b). The excellent performance of Ni/C stems from the good dispersion of the Ni nanoparticles over Ncontaining carbon support material.

Figure 1. CO2 conversion (XCO2) and CH4 selectivity (SCH4) on Ni/C, NiMo/C and NiRe/C at different temperatures (a) and over 90 h TOS (b).3

References

[1] A. Wieckowski, M. Neurock, Adv. Phys. Chem., 2011, 1–18. [2] J. Xu, X. Wei, J. D. Costa, J. L. Lado, B. Owens-Baird, L. P. L. Gonçalves, S. P. S. Fernandes, M. Heggen, D. Y. Petrovykh, R. E. Dunin-Borkowski, K. Kovnir, Y. V. Kolen’ko, ACS Catal., 2017, 7, 5450–5455. [3] L. P. L. Gonçalves, A. Serov, G. McCool, M. Dicome, J. P. S. Sousa, O. S. G. P. Soares, O. Bondarchuk, D. Y. Petrovykh, O. I. Lebedev, M. F. R. Pereira, Yu. V. Kolen’ko, ChemCatChem, 2021, DOI: 10.1002/cctc.202101284

Acknowledgments: L.P.L.G. thanks the FCT for the PhD grant support (SFRH/BD/128986/2017). This work was financially supported by: Base-UIDB/50020/2020 and Programmatic-UIDP/50020/2020 Funding of LSRE-LCM, funded by national funds through FCT/MCTES (PIDDAC). O.S.G.P.S. acknowledges FCT funding under the Scientific Employment Stimulus - Institutional Call CEECINST/00049/2018. Yu.V.K. thanks the FCT for support under the CritMag Project (PTDC/NAN-MAT/28745/2017). Pajarito acknowledges financial support from US DOE DE-FE0031878. A.S. acknowledges financial support from Oak Ridge National Laboratory SEED 10609 project “Single-Atom Catalysts for CO2 Conversion”. A.S. acknowledges catalysts samples provided by Pajarito Powder, LLC.

Influence of activated carbon surface chemistry on the removal of pharmaceutical compounds from water

Ana S. Mestrea, Elsa Mesquitab, A. Francisca Lopesa, Maria João Rosab, Ana P. Carvalhoa

aCentro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal. bUnidade de Qualidade e Tratamento de Água, Núcleo de Engenharia Sanitária, Departamento de Hidráulica e Ambiente, Laboratório Nacional de Engenharia Civil - LNEC, Lisboa, Portugal. E-mail: asmestre@fc.ul.pt

The presence of pharmaceutical compounds (PhCs) in wastewater treated effluents is driving the need for the upgrade of water treatment technologies, namely by adsorption processes employing activated carbon materials (ACs). 1 It is well known that the effectiveness of activated carbons is generally dependent on both their textural and surface properties, but the influence of the latter is scarcely addressed. In the present work the surface chemistry of a commercial AC (NucharA74) was modified by thermal treatments at 500 ºC (NucharA74/500) and 800 ºC (NucharA74/800) under N2 (see pHPZC values on Table 1). The textural properties of the materials were characterized by N2 adsorption at -196 ºC and FTIR spectra. Materials were tested for the simultaneous removal of three PhCs (100 µg/L) spiked in mineral aqueous solution. PhCs were selected considering their worldwide occurrence and persistence in wastewater treatment plant (WWTP) effluents (validated in LIFE IMPETUS, www.life-impetus.eu)and adsorption keyproperties: carbamazepine (CBZ - neutral, hydrophobic), diclofenac (DCF - anionic, relatively hydrophobic) and sulfamethoxazole (SMX - anionic, hydrophilic). 2 Concerning PhCs, DCF and CBZ were the most adsorbable compounds. The lower adsorbability of SMX may result from its hydrophilic character and higher polar surface area. The adsorptive capacity was generally more efficient for NucharA74/800, followed by NucharA74/500. The good performance of NucharA74/800 was attributed to its pHPZC value, as it has a lower negative net surface charge density than the other ACs. NucharA74/500 material, despite its high acidity and slightly smaller microporous volume than that of NucharA74, showed a higher adsorption capacity for allPhCs. Thus, the changes on the surface chemistry during the thermal treatment of NucharA74/500 may have favoured the adsorbent-adsorbate interactions, compensating the electrostatic repulsions. Table 1. Activated carbons’ textural properties, pHPZC and surface charge at pH 7.9.

Material ABET (m2/g)

Vtotal (cm3/g)

Vmicro (cm3/g)

Vmeso (cm3/g) pHpzc

Charge at pH 7.9

NucharA74 2067 1.44 0.72 0.72 3.9 (-) (-) NucharA74/500 1971 1.32 0.70 0.62 2.5 (-) (-) (-) NucharA74/800 1659 1.03 0.61 0.42 5.6 (-)

References

[1] Mestre, A.S.; Campinas, M.; Viegas, R.M.C.; Mesquita, E.; Carvalho, A.P.; Rosa, M.J.; Activated carbons in full-scale advanced wastewater treatment, in: D.A. Giannakoudakis, L. Meili, I. Anastopoulos (Ed.) Advanced Materials for Sustainable Environmental Remediation: Terrestrial and Aquatic Environments, Elsevier 2022. [2] Viegas, R.M.C.; Mestre, A.S.; Mesquita, E.; Campinas, M.; Andrade, M.A.; Carvalho, A.P.; Rosa, M.J.; Assessing the applicability of a new carob waste-derived powdered activated carbon to control pharmaceutical compounds in wastewater treatment, Science of The Total Environment 2020, 743, 140791.

Acknowledgments: This work was supported by Fundação para a Ciência e a Tecnologia (FCT) through grant UIDB/00100/2020 and Project EMPOWER+ (PTDC/EQU-EQU/6024/2020). Ana S. Mestre thanks FCT for the Assistant Research contract CEECIND/01371/2017 (Embrace Project). The authors acknowledge Ingevity for providing the commercial activated carbon NucharA.

Metal-free graphene oxide for the photocatalytic degradation of organic contaminants in aqueous phase

Marta Pedrosaa, Eliana S. Da Silvaa, Luisa M. Pastrana-Martínezb, Goran Drazicc ,

Polycarpos Falarasd, Joaquim L. Fariaa, José L. Figueiredoa, Adrián M.T. Silvaa

aLaboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal. bDepartment of Inorganic Chemistry, Faculty of Sciences, University of Granada, Campus Fuentenueva s/n, 18071 Granada, Spain. cDepartment for Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia. dNational Centre for Scientific Research ‘‘Demokritos”, Institute of Nanoscience and Nanotechnology, 15341, Agia Paraskevi Attikis, Athens, Greece. E-mail: pedrosa.marta@fe.up.pt

Graphene is a 2D material composed of a single layer of carbon atoms organized in a honeycomb network. Since the discovery of its potentialities, this material has been widely studied for very different applications. Given that the production of pure graphene requires complex procedures, the use of graphene derivatives like graphene oxide (GO) or reduced GO (rGO) can be an excellent alternative. There are several methodologies to oxidize graphite, which in turn produce carbon materials with different types and amounts of oxygen functionalities. Accordingly, in the pursuit for novel metal-free photocatalysts, two methods (Brodie’s and Hummers’) were applied for the production of GO, and the resulting materials were tested in the photocatalytic degradation of phenol. The Brodie’s-based carbon analogue (GO-B) was a successful photocatalyst for the degradation of phenol under near-UV/Vis and visible irradiation, presenting better performance than that prepared by the modified Hummers’ method (GO-H). The higher photocatalytic activity of GO-B was explained as a consequence of an efficient charge (electron-hole) separation process, in agreement with the observed lower amount of oxygen functionalities (25.80% vs 34.60 %, determined in GO-B vs GO-H by XPS) and carbonyl (C=O) surface groups in particular (1.29% vs 8.65 %, respectively), the smaller interlayer distance and the lower photoluminescence intensity in liquid dispersion.1

References

[1] Pedrosa, M.; Da Silva, E. S.; Pastrana-Martínez, L. M.; Drazic, G.; Falaras, P.; Faria, J. L.; Figueiredo, J. L.; Silva, A. M. T. J. Colloid Interface Sci., 2020, 567, 243-255.

Acknowledgments: This work was financially supported by project NORTE-01-0145-FEDER-031049 (InSpeCt) funded by FEDER funds through NORTE 2020 - Programa Operacional Regional do NORTE and by national funds (PIDDAC) through FCT/MCTES (PTDC/EAMAMB/31049/2017). We would also like to thank the scientific collaboration under projects 2DMAT4FUEL (POCI-01-0145-FEDER-029600 - COMPETE2020 – FCT/MCTES - PIDDAC) and base funding of the Associate Laboratory LSRE-LCM (UIDB/50020/2020 - FCT/MCTES – PIDDAC). MP acknowledges the project SAMPREP (POCI-01-0145-FEDER-030521- COMPETE2020 – FCT/MCTES - PIDDAC). L.M.P.-M. (RYC-2016-19347) acknowledges the Spanish Ministry of Economy and Competitiveness (MINECO).

Novel hybrids based on graphene quantum dots covalently linked to amino porphyrins for bioimaging

Carla I. M. Santosa,b, Laura Rodríguez-Pérezc, Gil Gonçalvesd, M. Amparo F. Faustinob , M. Ángeles Herranzc, Nazario Martinc, M. Graça P. M. S. Nevesb, José M. G. Martinhoa , Ermelinda M. S. Maçôasb

aCQE, Centro de Química Estrutural and IN-Institute of Nanoscience and Nanotechnology of Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. bLAQV-REQUIMTE, Department of

Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal. cDepartment of Organic Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid, Spain. dTEMA-Nanotechnology Research Group, Mechanical Engineering Department, University of Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal. E-mail: cims@ua.pt

Graphene quantum dots (GQDs) possess excellent optical and electronic properties coupled with high photostability, aqueous solubility and bio-compatibility.1 The presence of carboxyl and hydroxyl groups on their surface and edges enable covalent attachment, electrostatic interactions and hydrogen bonding with other suitable moieties.2 In addition, the nonlinear optical response of GQDs presents great opportunities for the development of optical sensors operating biological media.3 In order to evaluate the possibility of using GQDs to introduce a hydrophobic sensing unit inside animal cells and to add a nonlinear response to the sensing unit we have prepared hybrid nanoparticles by coupling GQDs with porphyrins. In the present study GQDs have been covalently functionalized with amino porphyrins via amide coupling. The optical and structural characterization of the resultant hybrid material is discussed. Preliminary studies on cellular uptake and distribution, using confocal and multiphoton microscopy, are presented.

Figure 1. Illustration of the structures of the amino porphyrins and the GQDs.

References

[1] C. I. M. Santos et al., Nanoscale, 2018, 10, 12505. [2] J. Gu et al., RSC Adv., 2014, 4, 50141. [3] M. Managa et al., Dyes Pigments, 2018, 148, 405.

Acknowledgments: Authors are grateful to Fundação para a Ciência e Tecnologia (FCT, Portugal), European Union, QREN, FEDER and COMPETE for funding the QOPNA, TEMA, CICECO and IST research units (project FCT UID/QUI/00062/2019, UID/CTM/50011/2019, PTDC/NAN-MAT/29317/2017, PTDC/QUI-QFI/29319/2017 and UID/NAN/50024/2019) and the Portuguese National NMR Network, also supported by funds from FCT. This work was also supported by the Ministerio de Ciencia, Innovación y Universidades (CIENCIA) of Spain (Projects CTQ2017-83531R and CTQ2017-84327-P).

Functional textiles based on MWCNTs and PEDOT: PSS composites for EMI shielding applications

Ana Rita Sousaa,b, José R. M. Barbosac , O. Salomé G.P. Soaresc, João Ferreirad, Gilda Santosd, Augusta Silvad, José Morgadod, Patrícia Soarese, Sergey A. Bunyaeva, Gleb N.

Kakazeia, Cristina Freireb, M. Fernando R. Pereirac, Clara Pereirab ,André M. Pereiraa

a IFIMUP - Institute of Physics for Advanced Materials, Nanotechnology and Photonics, Physics and Astronomy Department, Faculty of Sciences, University of Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal. bREQUIMTE/LAQV, Chemistry and Biochemistry Department, Faculty of Sciences, University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal. cLSRE-LCM, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal. dCITEVE - Technological Centre for the Textile and Clothing Industry of Portugal, Rua Fernando Mesquita, 2785, 4760-034 Vila Nova de Famalicão, Portugal. eCottonanswer, Rua dos Combatentes do Ultramar, 50, 4750-047 Lijó, Barcelos, Portugal. E-mail: up201204635@fc.up.pt

The constant development of technologies that use radiofrequency electromagnetic (EM) radiation, such as communication applications, wireless networks and self-controlled devices, has led to an excessive EM pollution that may affect human health and the performance of electronic equipment.1 In order to suppress these issues, electromagnetic interference (EMI) shields are being developed and improved. Carbon materials and conductive polymers have been studied for the attenuation of EM radiation owing to their remarkable electrical properties and low density.2 For instance, polymer composites are promising alternatives to metal-based materials, to overcome the limitations of low flexibility, tendency to corrosion and difficult processing of the latter. These properties are of special importance in the development of EMI shielding functional textiles. Herein, flexible (3,4-ethylenedioxythiophene):polystyrene sulfonate/multiwalled carbon nanotube coated textiles (PEDOT:PSS/MWCNT@tex) were fabricated through a coating process. The shielding effectiveness (SE) was investigated over the frequency range of 5.85–18 GHz using the transmission line test with waveguides. The EMI shielding properties were explored for different loadings of MWCNTs and PEDOT:PSS. Average SE values above 30 dB were obtained for MWCNT loadings above 5 wt.% in the measured band frequency, and a promising result of SE above 60 dB was achieved for frequencies above 13 GHz. These results are classified as excellent for general use and, in the case of the SE above 60 dB, as excellent for professional use.3

References

[1] Batool, S., Bibi, A., Frezza, F., Mangini, F., Benefits and hazards of electromagnetic waves, telecommunication, physical and biomedical: a review. Eur. Rev. Med. Pharmacol. Sci., 2019, 23, 3121-3128. [2] Jiang, D., Murugadoss, V., Wang, Y., Lin, J., Ding, T., Wang, Z., Shao, Q., Wang, C., Liu, H., Lu, N., Wei, R., Subramania, A., Guo, Z., Electromagnetic Interference Shielding Polymers and Nanocomposites - A Review. Polym. Rev., 2019. 59, 280-337. [3] FTTS-FA-003, Test Method of Specified Requirements of Electromagnetic Shielding Textiles. 2005. p. 1-4.

Acknowledgments: This work was supported by FEDER through COMPETE 2020 under the project RFProTex - POCI01-0247-FEDER-039833, and by FCT/MCTES through national funds in the framework of the projects UIDB/50020/2020, UIDB/50006/2020 and UIDB/04968/2020 and UIDP/50020/2020. A. S. thanks FEDER through COMPETE 2020 for PhD scholarship (POCI-01-0247-FEDER-039833). O.S.G.P.S. acknowledges FCT funding under the Scientific Employment Stimulus - Institutional Call CEECINST/00049/2018. C. P. thanks FCT for the FCT Investigator contract IF/01080/2015.