Browsing by Author "Santangelo, Saveria"
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Item Bacterial-cellulose-derived carbonaceous electrode materials for water desalination via capacitive method: The crucial role of defect sites: The crucial role of defect sites(2020-10-15) Belaustegui, Yolanda; Pantò, Fabiola; Urbina, Leire; Corcuera, Maria Angeles; Eceiza, Arantxa; Palella, Alessandra; Triolo, Claudia; Santangelo, Saveria; VALORIZACIÓN DE RESIDUOSElectrosorptive desalination is a very simple and appealing approach to satisfy the increasing demand for drinking water. The large-scale application of this technology calls for the development of easy-to-produce, cheap and highly performing electrode materials and for the identification and tailoring of their most influential properties, as well. Here, biosynthesised bacterial cellulose is used as a carbon precursor for the production of three-dimensional nanostructures endowed with hierarchically porous architecture and different density and type of intrinsic and hetero-atom induced lattice defects. The produced materials exhibit unprecedented desalination capacities for carbon-based electrodes. At an initial concentration of 585 mg L−1 (10 mmol L−1), they are able to remove from 55 to 79 mg g−1 of salt; as the initial concentration rises to 11.7 g L−1 (200 mmol L−1), their salt adsorption capacity reaches values ranging between 1.03 and 1.35 g g−1. The results of the thorough material characterisation by complementary techniques evidence that the relative amount of oxygenated surface functional species enhancing the electrode wettability play a crucial role at lower NaCl concentrations, whereas the availability of active non-sp2 defect sites for adsorption is mainly influential at higher salt concentrations.Item Electro-spun graphene-enriched carbon fibres with high nitrogen-contents for electrochemical water desalination(2018-02-15) Belaustegui, Yolanda; Zorita, Saioa; Fernández-Carretero, Francisco; García-Luis, Alberto; Pantò, Fabiola; Stelitano, Sara; Frontera, Patrizia; Antonucci, Pierluigi; Santangelo, Saveria; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; ADAPTACIÓN AL CAMBIO CLIMÁTICO; TECNOLOGÍAS DE HIDRÓGENOElectro-spun carbon fibres doped with very high nitrogen concentrations (19–21 wt%) are obtained operating carbonisation at low temperature (500 °C). The as-synthesised fibres are evaluated as electrode materials for the electrochemical desalination of water. The effect of the enrichment of the nitrogen doped carbon fibres with thermally reduced graphene oxide is also investigated. The fibrous electrodes are able to remove amazing amounts of NaCl (17.0–27.6 mg/g) from a salty solution with an initial concentration of 585 mg/L. The nitrogen doping, which dramatically improves the wettability, plays a crucial role in determining the outstanding electro-sorption capacities of the fibres. It allows fully profiting of the more favourable pore size distribution in the graphene-enriched fibres, endowed with higher conductivity and capacitance, for the obtainment of unprecedented electro-sorption capacities via an extremely simple synthesis process, with no need of activation treatments.Item Evaluation of the electrochemical performance of electrospun transition metal oxide-based electrode nanomaterials for water CDI applications(2019-06-20) Santangelo, Saveria; Pantò, Fabiola; Triolo, Claudia; Stelitano, Sara; Frontera, Patrizia; Fernández-Carretero, Francisco; Rincon, Inés; Azpiroz, Patxi; García-Luis, Alberto; Belaustegui, Yolanda; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; VALORIZACIÓN DE RESIDUOSComposite fibrous materials based on (graphene-enriched) nitrogen-doped carbon/transition metal oxides were produced by electrospinning and their physicochemical properties were thoroughly investigated by a combination of characterisation techniques. The electrochemical behaviour of the electrodes prepared with them was evaluated in view of their use in the capacitive deionisation of saline water. The morphology of the materials reminded of usnea florida lichens, wheat ears, sea sponges and noodles and depended on the transition metal (Mn, Fe, Ti or Zn). The morphology and the relative amount (14.1–22.2 wt%) of the surface nitrogen and carbon-bonded oxygen functional species, beneficial to wettability and involving pseudocapacitive processes, had strong impact on the specific capacitance (43.7–67.4 F g−1, at 5 m V s−1 scan rate), whereas also the specific micropore volume (0.4–5.6 mm3 g−1) affected the effective areal capacitance of the electrodes (1.2–6.0 F m−2, at 5 mV s−1). Ion storage in the composite materials occurred via a mixed capacitive/pseudocapacitive process. Hence, increasing the content of the oxide (from 24.6 to 56.7 wt%), thanks to the fast-reversible redox reactions at or near surface it involves, partly compensated for the growing hindrance to diffusion encountered by the ions (hampered electrostatic adsorption) as the scan rate increased from 5 to 100 mV s−1.Item Evaluation of the Specific Capacitance of High-Entropy Oxide-Based Electrode Materials in View of Their Use for Water Desalination via Capacitive Method(Multidisciplinary Digital Publishing Institute (MDPI), 2023-01-04) Triolo, Claudia; Santangelo, Saveria; Petrovičovà, Beatrix; Musolino, Maria Grazia; Rincón, Inés; Atxirika, Ainhoa; Gil, Silvia; Belaustegui, YolandaWater pollution and scarcity are serious concerns for the growing world population. To meet the ever-pressing demand of fresh water, a variety of desalting techniques of seawater have been developed. Due to its environmental friendliness, high efficiency, easy regeneration of the electrodes, ambient operating pressure, and low operating potential suitable for the use in remote areas, the capacitive deionization (CDI) method is one of the most sustainable among them. This work focuses on the preparation of high-entropy oxides (HEOs) and carbon/HEO composites and the evaluation of their specific capacitance in view of their possible use as CDI electrode materials. CrMnFeCoNi-HEO, having spinel structure (sHEO), is obtained in the form of nanoparticles (NPs) and nanofibers (NFs) by the sol–gel method and electrospinning, respectively. Composite NFs with embedded sHEO NPs or MgCoNiCuZn-HEO NPs with rock-salt structure (rHEO) are also produced. In the 5–100 mV s−1 scan rate range, the specific capacitance improves in the order C/rHEO NFs (8–32 F g−1) ≅ sHEO NPs (9–32 F g−1) < sHEO NFs (8–43 F g−1) < C/sHEO NFs (12–66 F g−1). The highest capacitance is obtained when the beneficial contributions of the carbon matrix and smaller-sized HEO NPs are synergistically coupled.