New Insights into the Photocatalytic Properties of RuO2/TiO2 Mesoporous Heterostructures for Hydrogen Production and Organic Pollutant Photodecomposition

Abstract

Photocatalytic activities of mesoporous RuO2/TiO2 heterojunction nanocomposites for organic dye decomposition and H2 production by methanol photoreforming have been studied as a function of the RuO2 loading in the 1–10 wt % range. An optimum RuO2 loading was evidenced for both kinds of reaction, the corresponding nanocomposites showing much higher activities than pure TiO2 and commercial reference P25. Thus, 1 wt % RuO2/TiO2 photocatalyst led to the highest rates for the degradation of cationic (methylene blue) and anionic (methyl orange) dyes under UV light illumination. To get a better understanding of the mechanisms involved, a comprehensive investigation on the photogenerated charge carriers, detected by electron spin resonance (ESR) spectroscopy in the form of O–, Ti3+, and O2– trapping centers, was performed. Along with the key role of superoxide paramagnetic species in the photodecomposition of organic dyes, ESR measurements revealed a higher amount of trapped holes in the case of the 1 wt % RuO2/T...