Effect of Wetting on the Ability of Nanomaterials to Act as Effective Catalysts

Abstract

The ability of some nanostructured materials to perform as effective heterogeneous catalysts is potentially hindered by the failure of the liquid reactant to effectively wet the solid catalyst surface. In this work , two different chemical reactions, each involving a change of phase from liquid to gas on a solid catalyst surface, are investigated. The first reaction is the catalyzed decomposition of a H 2 O 2 monopropellant within a micro-chemical reactor chamber, decorated with RuO 2 nanorods (NRs). The second reaction involves the electrolysis of dilute aqueous solutions of H 2 SO 4 performed with the cathode electrode coated with different densities and sizes of RuO 2 NRs. In the catalyzed H 2 O 2 decomposition, the reaction rate is observed to decrease with increasing catalyst surface density because of a failure of the liquid to wet on the catalyst surface. In the electrolysis experiment, however, the reaction rate increased in proportion to the surface density of RuO 2 NRs. In this case , the electrical bias applied to drive the electrolysis reaction also causes an electrostatic force of attraction between the fluid and the NR coated surface, and thus assures effective wetting.