Enhanced catalytic activity of hierarchically macro-/mesoporous Pt/TiO₂ toward room-temperature decomposition of formaldehyde

Hierarchically macro-/mesoporous Pt/TiO₂ is prepared by hydrothermally treating the tetrabutyl titanate (Ti(OC₄H₉)₄) precipitates in pure water, followed by a combined NaOH-assisted NaBH₄-reduction deposition of Pt nanoparticles (NPs) on the TiO₂ surface. The catalytic activity toward the catalytic decomposition of formaldehyde (HCHO) vapor in air at ambient temperature is evaluated. The prepared Pt/TiO₂ catalyst exhibits excellent catalytic activity and recyclability, and 90.6% HCHO with an initial concentration of ca. 265 ppm can be completely decomposed within 60 min, which is significantly higher than that using commercial-grade Degussa P25 TiO₂ with an equal Pt-loading amount (56.2% HCHO decomposition). The high catalytic activity can be mainly attributed to the hierarchically macro-/mesoporous structures of the TiO₂ support with large specific surface area and optimal pore size. These characteristics not only enhance the adsorption of HCHO molecules, as well as facilitate the diffusion and transport of reactants and products, but also promote the dispersion of Pt NPs with small particle size inside and outside the pores. This study demonstrates that hierarchically macro-/mesoporous Pt/TiO₂ can serve as an efficient catalyst for indoor HCHO decomposition and will provide new insights into the environmentally benign design and preparation of low-cost and high-performance catalysts for indoor air purification. Copyright © 2015 The Royal Society of Chemistry.