Resumo O crescimento de filmes de TiO2 dopados com nitrogênio sobre vidro borossilicato foi efetuado a 400 °C por deposição química de organometálicos em fase vapor (MOCVD) visando a remoção de corantes da água sob luz visível. O efeito da dopagem nas propriedades estruturais, morfológicas e fotocatalíticas dos filmes foi avaliado. Análises por espectroscopia de fotoelétrons excitados por raios X (XPS) revelaram teores de 1,56 e 2,44 at% de nitrogênio nos filmes, ao variar o fluxo de NH3 durante o crescimento. Experimentos de degradação do corante alaranjado de metila mostraram que os filmes dopados apresentaram fotoatividade em luz visível. O filme contendo 2,44 at% de nitrogênio apresentou o melhor desempenho fotocatalítico, com 55% de eficiência. Os testes de reutilização demonstraram que a eficiência dos filmes diminuiu gradativamente após cada ensaio. Os filmes de N-TiO2 têm potencial para serem utilizados em aplicações ambientais, removendo poluentes a partir de uma tecnologia verde sob luz solar ou iluminação interna, embora sua reutilização seja limitada.

Abstract Nitrogen-doped TiO2 films were grown on borosilicate glass substrates at 400 °C by the metallorganic chemical vapor deposition (MOCVD) for removing dye from water under visible light. The effect of N-doping on the structural, surface, and photocatalytic properties of films was evaluated. X-ray photoelectron spectroscopy (XPS) analyses revealed that 1.56 and 2.44 at% of nitrogen were incorporated into the films by varying the NH3 flux during the growth. Methyl orange dye degradation experiments showed that the N-doped films presented photoactivity under visible light. The film containing 2.44 at% of nitrogen exhibited the best photocatalytic behavior, with 55% of efficiency. Recyclability tests under visible light showed that the film efficiency dropped gradually after each test. N-TiO2 films grown by MOCVD have the potential to be used in environmental applications by removing pollutants using a green method under sunlight or even under internal illumination, although its reuse is limited.

PtRu/C electrocatalysts were prepared by hydrothermal carbonization process using starch as carbon sources and reducing agents and platinum and ruthenium salts as catalysts of carbonization process and metals source. pH of the reaction medium was adjusted using KOH or TPAOH (tetrapropylammonium hydroxide). The obtained PtRu/C electrocatalysts were characterized by SEM/EDX, TGA, XRD and cyclic voltammetry. The electro-oxidation of methanol was studied by cyclic voltammetry and chronoamperometry. The PtRu/C electrocatalyst prepared using TPAOH was more active for methanol electro-oxidation than the material prepared with KOH.