Polypyrrole-Coated SnO₂ Hollow Spheres and Their Application for Ammonia Sensor

Abstract

Polypyrrole-coated SnO 2 hollow spheres hybrid materials have been synthesized through an in situ polymerization of pyrrole monomers in the presence of preprepared SnO 2 hollow spheres. The hybrids were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), and thermogravimetric analysis (TG). Experimental data showed certain synergetic interaction existed in the hybrids, probably resulting in the enhanced thermal stability of polypyrrole coatings. Gas sensing tests showed that the hybrids possessed very fast response and high sensitivity to ammonia gas at room temperature, implying its potential application for gas sensors.

Electrochemical synthesis of highly ordered polypyrrole on copper modified aluminium substrates

“…2(b)) and the corresponding FWHM is found to be 0.31°. This observed XRD peak is much sharper than those reported previously (FWHM 10°) for PPy [8], [17], [20] and [21]. The calculated d-spacing using Bragg's equation on our PPy films deposited on copper modified aluminium surfaces is found to be 3.8 Å and this value is consistent with those reported previously [8] and [21].…”

Biomineralization of a titanium-modified hydroxyapatite semiconductor on conductive wool fibers

“…Four sets of TiHAs, all of which displayed band gap values comparable those of wide band 40 gap semiconductors [21][22][23] , were obtained by wet synthesis by adjusting the concentration of the 41 titanium dopant in the growth solution. The TiHA sample displaying optimal properties was 42 then deposited on PPy -coated wool fibers under room temperature by a bio-inspired 43 mineralization, where this ensured that the wool fibers retained their flexibility and softness.…”

Preparação e caracterização elétrica de sensores de metanol à base de nanocompósitos híbridos de polipirrol/nanopartículas metálicas

“…A partir dos resultados apresentados na Figura 2 verificamos que o acréscimo na absorbância para comprimento de onda na ordem de 700 nm caracteriza a formação de níveis bipolarônicos [22,23,31] . Como mostram as curvas inseridas no topo da Figura 2, a ausência de agente estabilizante conduz o sistema a um grau reduzido de dopagem, considerando a progressiva formação de agregados, conforme mostrado na Figura 1.…”

“…que tratam do processo de detecção da amônia por sensores de polipirrol [20][21][22][23] . Nesta situação, a forma protonada do PPy interage com o gás, que então estabelece a desprotonação do átomo de nitrogênio do polipirrol [20] , caracterizando esse como um processo irreversível, em que se tem uma diminuição na condutividade da amostra, que vem a caracterizar a detecção do volátil [20] .…”