Navegando por Autor "Rodrigues, Jairo Lisboa"
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Item Photoassisted chemical energy conversion into electricity using a sulfite-iron photocatalytic fuel cell.(2021) Sena, Izabela Campos; Sales, Davi de Oliveira; Andrade, Tatiana Santos; Rodriguez, Mariandry del Valle Rodriguez; Silva, Adilson Cândido da; Nogueira, Francisco Guilherme Esteves; Rodrigues, Jairo Lisboa; Mesquita, João Paulo de; Pereira, Márcio CésarPhotocatalytic fuel cells (PFC) are light-assisted devices that convert chemical energy into electricity. However, con ventional PFC produces extremely low photocurrents due to the slow kinetics of the photoanodes to oxidized organic fuels, thus limiting the power generation. Here, an all-inorganic PFC manufactured with heterostructured W-BiVO4/ V2O5 photoanode separated from a platinum cathode by a porous membrane is described. Sulfite ions are used as a fuel anolyte and Fe3+ is the catholyte. Under lighting, the W-BiVO4/V2O5 photoanode is exceptionally efficient for oxidizing sulfite to sulfate, which results in a high photocurrent output. Under optimized conditions, the W-BiVO4/V2O5-Pt cell produces a high short-circuit current of 8.79 mA cm−2 , an open-circuit potential 0.85 V, and a power density of 1.89 mW cm−2 at 4.30 mA cm−2 . The excellent PFC performance is attributed to the photovoltage generated by W-BiVO4/sulfite-sulfate liquid-junctions and efficient charge separation and hole transport in the photoanode bulk promoted by the W-BiVO4/V2O5 junctions. Also, the kinetics of redox reactions are fast, eliminating the use of cocatalysts. Thus, this simple PFC concept can be a viable alternative for electricity generation.Item Room temperature selective conversion of aniline to azoxybenzene over an amorphous niobium oxyhydroxide supported on δ-FeOOH.(2018) Lima, André L. D.; Batalha, Daniel Carreira; Fajardo, Humberto Vieira; Rodrigues, Jairo Lisboa; Pereira, Márcio César; Silva, Adilson Cândido daIn this work, catalysts for the oxidation of aniline into azoxybenzene were prepared by combining δ-FeOOH nanoparticles with 0, 2.5, 5, and 10 wt.% niobium oxyhydroxides by a simple co-precipitation method. The niobium oxyhydroxide actively changed the chemical and textural properties of δ-FeOOH, as verified by XRD, Mössbauer spectroscopy, N2 adsorption-desorption measurements, and TEM images. Therefore, the catalytic performance of δ-FeOOH to convert aniline into azoxybenzene in the presence of hydrogen peroxide was significantly improved. The catalytic activity and selectivity changed with the Nb content in the composite. The effect of different reaction parameters like solvent type, H2O2 volume, and reaction time has been studied in detail. The catalyst with 10 wt.% Nb was the most efficient among the evaluated catalysts, showing 100% conversion of aniline with 80.2% selectivity to azoxybenzene when propanol was used as solvent at 25 °C. Moreover, the catalyst 10 wt.% Nb exhibited good stability and could be reused for various cycles without significant loss of catalytic activity.