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- Evolution of atomically dispersed co-catalysts during solar or UV photocatalysis for efficient and sustained H2 productionPublication . Capelo, Anabela; Fattoruso, Domenico; Valencia-Valero, Laura; Esteves, M. Alexandra; Rangel, Carmen M.; Puga, AlbertoABSTRACT: The evolution of metal/titania photocatalysts during photocatalytic H-2 evolution is herein studied. Samples containing atomically dispersed Pt co-catalysts (single atoms, clusters and sub-nanoparticles) formed after calcination were compared to pre-reduced analogues mostly having metallic nanoparticles (diameters >1 nm) during ethanol photoreforming under either UV-rich irradiation or natural sunlight. Aggregation of ultra-dispersed oxidised platinum entities (Pt delta+) with concomitant reduction into Pt-0 nanoparticles (1-2 nm) was observed after UV irradiation by transmission electron microscopy (TEM), and diffuse reflectance UV-visible (DRUV-vis) and X-ray photoelectron (XPS) spectroscopies. A parallel, albeit slower, evolution trend was evidenced during solar photocatalysis. Conversely, atomically dispersed Cu co-catalyst species did not grow and became in-situ reduced into sub-nanometric Cu-0 under irradiation. Hydrogen production rates were remarkably high during initial stages of UV irradiation, and then declined to a sustained regime (approximate to 50 and 8 mmol g(-1) h(-1) for Pt/TiO2 or Cu/TiO2, respectively, for up to 24 h of irradiation). Steadier solar photoreforming was observed in experiments performed in a compound parabolic collector tubular reactor (approximate to 7.6 and 1.7 mmol g(-1) h(-1) for Pt/TiO2 or Cu/TiO2, respectively). Despite the non-negligible effect of co-catalyst rearrangement on activity rationalised herein, attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy measurements pre- and post-photocatalysis suggest that accumulation of strongly adsorbed degradation intermediates, chiefly acetate, is a major cause for rate decreases. Notwithstanding, this phenomenon did not result in total deactivation, so that sustained hydrogen production upon long-term irradiation was not compromised.
- Dielectric UV filters for protection of fire-resistant glass based on intumescent layersPublication . Silva, Ricardo Magno Lopes; Hashim, Hurraira; Roy, Deepto; Oliveira Fernandes, Carolina; Oliveira, Kevin; Leitão Pinheiro, Xavier Alexandre; Esteves, M. Alexandra; Capelo, Anabela; Donato, Mariana; Oliveira, Fernando; Ferreira, Cristina; Alves, Isabel N.; Cunha Diamantino, Teresa; Barreiros, Maria Alexandra; Rocha, Jorge; Passos Teixeira, Jennifer; Salomé, PedroABSTRACT: Structures such as OLEDs, perovskite solar cells, intumescent glasses, and other components in modern devices and buildings contain materials suscep-tible to degradation when exposed to UV radiation, requiring protection to with-stand outdoor environmental conditions. In this work, multilayer coating config-ured as a Bragg Reflector on glass is employed as spectral filtering to protect the intumescent component of fire-resistant glass from degradation due to prolonged UV solar radiation exposure. By alternating low-n (SiO2)/high-n (TiO2) dielectric layers through spin-coating, precise control over film thickness could be achieved, allowing the fabrication of thin (<700 nm) UV filters with high trans-mission of visible sunlight – 88% of the 780 to 380 nm wavelength range – while reflecting almost all the incident UV – 90% of the wavelength below 380nm. Using relatively simple techniques, high precision coating was successfully achieved, resulting in an effective UV radiation protective barrier applied to en-hance the durability of the components in fire-resistant glass.
- Fire-resistant materials: characterization and thermal behavior of intumescent gels for fire resistant glass [Poster]Publication . Donato, Mariana; Esteves, M. Alexandra; Capelo, Anabela; Oliveira, Fernando; Ferreira, Cristina; Alves, Isabel N.; Morgado, Vanessa; Correia, Jose B.; Teixeira, Jennifer P.; Oliveira Fernandes, Carolina; Silva, Ricardo Magno Lopes; Rocha, Jorge; Salomé, Pedro; Cunha Diamantino, Teresa; Barreiros, Maria Alexandra
- Intumescent Gels for Fire-Resistant Glass: Thermal Insulation, UV Protection, and Durability Studies [Comunicação oral]Publication . Esteves, M. Alexandra; Capelo, Anabela; Donato, Mariana; Oliveira, Fernando; Ferreira, Cristina; Alves, Isabel N.; Correia, Jose B.; Silva, Ricardo Magno Lopes; Hashim, Hurraira; Roy, Deepto; Passos Teixeira, Jennifer; Rocha, Jorge; Salomé, Pedro; Cunha Diamantino, Teresa; Barreiros, Maria Alexandra
- Intumescent Gels for Fire-Resistant Glass: Thermal Insulation, UV Protection, and Durability Studies [Poster]Publication . Esteves, M. Alexandra; Capelo, Anabela; Donato, Mariana; Oliveira, Fernando; Ferreira, Cristina; Alves, Isabel N.; Correia, Jose B.; Silva, Ricardo Magno Lopes; Hashim, Hurraira; Roy, Deepto; Passos Teixeira, Jennifer; Rocha, Jorge; Salomé, Pedro; Cunha Diamantino, Teresa; Barreiros, Maria Alexandra
- Dielectric UV filters for protection of fire-resistant glass based on intumescent layers [Comunicação oral]Publication . Silva, Ricardo Magno Lopes; Hashim, Hurraira; Roy, Deepto; Oliveira Fernandes, Carolina; Oliveira, Kevin; Leitão Pinheiro, Xavier Alexandre; Esteves, M. Alexandra; Capelo, Anabela; Donato, Mariana; Oliveira, Fernando; Ferreira, Cristina; Alves, Isabel N.; Cunha Diamantino, Teresa; Barreiros, Maria Alexandra; Rocha, Jorge; Passos Teixeira, Jennifer; Salomé, Pedro
- Optimised photocatalytic H2 production using nanostructured low cost and sustainable photocatalystsPublication . Esteves, M. Alexandra; Brites, Maria João de Sousa; Capelo, Anabela; Pinheiro, Carla I.C.; Lanham, Ana; Ramos, Diana; Pedro, GuilhermeABSTRACT: The SPECTRUM project aims to design, develop, prototype, and test lab-scale solar collectors that effectively utilise the entire solar spectrum to cogenerate heat, electricity and hydrogen. SPECTRUM Work package 1 is dedicated to the optimization of the photocatalytic process of industrial wastewater (IWW) treatment and hydrogen generation and is divided in four tasks. This deliverable D1.3 provides an account of the activities carried out in Task 1.3, “Optimization of Photocatalytic H₂ Production Process at Laboratory Scale,” as well as the results achieved during its duration. The photocatalysts developed in Task 1.2, “Development of nanostructured low cost and sustainable photocatalyst”, were tested for hydrogen production in a slurry type batch reactor using UV radiation as light source. In these preliminary assays, synthetic aqueous solutions containing ethanol or glycerol as sacrificial agent (SA) were used to test the performance of a first series of copper decorated TiO2 nanoparticles (NP) photocatalysts. A comprehensive series of experiments enabled the selection of the most effective photocatalyst, Cu-decorated TiO2 nanoparticles with 6 weight % of copper (Cu/TNP-6). This photocatalyst was then utilized with aqueous solutions of ethanol or glycerol to optimize three key operational parameters — pH, photocatalyst concentration, and sacrificial agent concentration. The same methodology was subsequently applied to evaluate the performance of two additional copper-based photocatalyst sets developed in Task 1.2: copper-decorated TiO₂ nanotubes and copper/biochar-decorated TiO₂ nanoparticles.
- Development of nanostructured sustainable photocatalysts for industrial wastewater remediation with co-generation of H2Publication . Esteves, M. Alexandra; Brites, Maria João de Sousa; Capelo, Anabela; Pasquini, Luca; Mazzaro, RaffaelloABSTRACT: The SPECTRUM project aims to design, develop, prototype, and test lab-scale solar collectors that effectively utilize the entire solar spectrum to cogenerate heat, electricity and hydrogen using industrial wastewater. This report presents the results of the activities developed in Task 1.2 Development of nanostructured low cost and sustainable photocatalysts of SPECTRUM’s Work Package 1, Optimization of the photocatalytic process of wastewater treatment and hydrogen generation. One of the Specific Objectives (SO1) of the SPECTRUM project is to develop low cost and sustainable nanostructured photocatalysts for synergetic pollutants degradation and H2 generation. With this goal, nanostructured titanium dioxide (TiO₂) photocatalysts were developed using copper as an efficient and economical co-catalyst, suitable for large-scale hydrogen production systems. Two series of copper-decorated TiO2 photocatalysts were synthesized, one based on TiO2 nanoparticles (NP) (Series I) and another based on TiO2 nanotubes (NT) (Series II).