Sensores de gás nanoestruturados para CO (g) : coisa “céria”
Arquivos
Data
2019-03-21
Autores
Rocha, Leandro Silva Rosa [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Devido à problemática das intoxicações com monóxido de carbono ser responsável pelo maior tipo de envenenamento do século 21, objetivou-se a produção de materiais nanoestruturados a base de céria, pura e dopada com lantânio (La 3+ ), através do método hidrotermal assistido por micro-ondas com posterior deposição na forma de filmes, para caracterização como dispositivos sensores na detecção de atmosfera de CO, por meio da técnica de sonda de duas pontas. O método de síntese empregado foi eficaz na produção de nanopartículas, com dimensões inferiores a 10 nm, apresentando elevada cristalinidade, caracterizada por um ordenamento periódico a curta e longas distâncias, além da ausência de fases secundárias, comprovadas pelas caracterizações realizadas por difratometria de raios-X (DRX), bem como pelas técnicas de espectroscopias Raman, Infravermelho, Ultravioleta- Visível ou ainda por Ressonância Paramagnética de Elétrons. Os filmes depositados apresentaram uma resposta frente ao gás CO extremamente rápida e seletiva, com tempos de resposta em 54, 12, 5.5 e 2 s para as amostras pura e dopadas com lantânio em 4, 8 e 12%, respectivamente. Além da resposta elétrica, os filmes apresentaram ainda uma resposta óptica, com destaque para a amostra com 8%, a qual muda de cor em menos de 1s, a 380 °C sob pressão de 5 mmHg de CO, tornando-se promissores sensores de gás com resposta dupla (óptica e elétrica).
Due to the intoxication from carbon monoxide poisoning being responsible for the biggest type of poisoning in the 21st century, this work aimed to develop pure and lanthanum-doped nanostructured ceria-based materials using the microwave assisted hydrothermal (MAH) method with late deposition as films for the characterization as gas sensor devices for CO detection through the two-wire technique. The employed synthesis method proved to be effective in the production of nanoparticles with dimensions below 10 nm, presenting high cristallinity, characterized by a short and long-range order, besides the absence of secondary phases, depicted in the performed characterizations by means of x-rays diffratometry, as well as Raman, FT-IR, UV-Vis and EPR spectroscopies. The as-deposited films showed an extremely rapid and selective response when exposed to CO, with response times of 54, 12, 5.5 and 2 s for pure, 4, 8 and 12% lanthanum-doped samples, respectively. Besides the electrical response, the films showed an optical response, highlighting the sample with 8%, which changes its color in less than 1 s, at 380 °C under a pressure of 5 mmHg of CO, becoming promising dual gas sensors (optical and electric).
Due to the intoxication from carbon monoxide poisoning being responsible for the biggest type of poisoning in the 21st century, this work aimed to develop pure and lanthanum-doped nanostructured ceria-based materials using the microwave assisted hydrothermal (MAH) method with late deposition as films for the characterization as gas sensor devices for CO detection through the two-wire technique. The employed synthesis method proved to be effective in the production of nanoparticles with dimensions below 10 nm, presenting high cristallinity, characterized by a short and long-range order, besides the absence of secondary phases, depicted in the performed characterizations by means of x-rays diffratometry, as well as Raman, FT-IR, UV-Vis and EPR spectroscopies. The as-deposited films showed an extremely rapid and selective response when exposed to CO, with response times of 54, 12, 5.5 and 2 s for pure, 4, 8 and 12% lanthanum-doped samples, respectively. Besides the electrical response, the films showed an optical response, highlighting the sample with 8%, which changes its color in less than 1 s, at 380 °C under a pressure of 5 mmHg of CO, becoming promising dual gas sensors (optical and electric).
Descrição
Palavras-chave
Dióxido de cério, Lantânio, sensores de gases, Óxidos de cério, Monóxido de carbono, Materiais nanoestruturados, Cerium dioxide, Lanthanum, Gas sensors, Carbon monoxide