Síntese e otimização do uso do fotoanodo FTO/BiVO4 para aplicação em fotoeletrocatálise
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Data
2018-07-06
Autores
Alves, Nayara de Araujo
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O vanadato de bismuto tem sido muito estudado na sua aplicação em fotoeletrocatálise devido suas propriedades intrínsecas, mais precisamente na degradação de compostos orgânicos em meio aquoso utilizando a luz solar. Nesse trabalho o vanadato de bismuto, na forma de filme fino depositado em substrato condutor FTO através do processo de deposição via imersão, foi obtido por meio da técnica de síntese de combustão em solução (SCS). Para caracterização morfológica e estrutural do filme, foram realizadas medidas de DRX, MEVEDS e UV-Vis. Na caracterização eletroquímica e fotoeletroquímica, o fotoanodo FTO/BiVO4 foi avaliado em diferentes eletrólitos e pH, a fim de analisar a densidade de fotocorrente gerada com a influência dos ânions e cátions na atividade fotoeletrocatalítica. Medidas de Espectroscopia de Impedância eletroquímica também foram realizadas a fim de elucidar os processos eletroquímicos que acontecem na interface eletrodo/solução sob excitação luminosa. Foi observado que a resistência da transferência de cargas controla a cinética da reação de oxidação das espécies na interface do eletrodo. A sensibilidade do fotoanodo à glicose foi bem maior nas medidas fotocronoamperométricas comparadas às cronoamperométricas.
Bismuth vanadate has been extensively studied in its application in photoelectrocatalysis due to its intrinsic properties, more precisely in the degradation of organic compounds in aqueous media using sunlight. In this work the bismuth vanadate, in the form of a thin film deposited in the conducting substrate FTO through the immersion deposition process, was obtained through the solution combustion synthesis (SCS) technique. For the morphological and structural characterization of the film, X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS) images and UV-Vis spectra measurements were performed. In the electrochemical and photoelectrochemical characterization, the FTO/BiVO4 photoanode was evaluated in different electrolytes and pH in order to analyze the photocurrent density generated under the influence of the anions and cations in the photoeletrocatalytic activity. Electrochemical Impedance Spectroscopy measurements were carried out to elucidate the electrochemical processes that occur at the electrode / solution interface under light excitation. It was observed that the load transfer resistance controls the kinetics of the oxidation reaction of the species at the interface of the electrode. The sensitivity of the photoanode to the glucose was much higher in the photochronoamperometric measurements compared to the chronoamperometric ones.
Bismuth vanadate has been extensively studied in its application in photoelectrocatalysis due to its intrinsic properties, more precisely in the degradation of organic compounds in aqueous media using sunlight. In this work the bismuth vanadate, in the form of a thin film deposited in the conducting substrate FTO through the immersion deposition process, was obtained through the solution combustion synthesis (SCS) technique. For the morphological and structural characterization of the film, X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS) images and UV-Vis spectra measurements were performed. In the electrochemical and photoelectrochemical characterization, the FTO/BiVO4 photoanode was evaluated in different electrolytes and pH in order to analyze the photocurrent density generated under the influence of the anions and cations in the photoeletrocatalytic activity. Electrochemical Impedance Spectroscopy measurements were carried out to elucidate the electrochemical processes that occur at the electrode / solution interface under light excitation. It was observed that the load transfer resistance controls the kinetics of the oxidation reaction of the species at the interface of the electrode. The sensitivity of the photoanode to the glucose was much higher in the photochronoamperometric measurements compared to the chronoamperometric ones.
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Palavras-chave
Vanadato de bismuto, Células fotoeletroquímicas, Fotoeletrocatálise, Bismuth vanadate, Photoelectrochemical cells, Photoelectrocatalysis