Porous Perovskite Materials in Catalysis

Abstract

EditorialPerovskite-type oxides with the general formula ABO 3 containing both rare earth elements and 3d transition metals have received intensive attention in recent years due to their wide range of applications in adsorption, separation, catalysis, and sensors. In terms of the heterogeneous catalysis, the reaction always involves diffusion and adsorption of reactants on the surface of catalyst, surface reaction of adsorbed species and desorption of products. Clearly, the reactions happened on the surface of catalyst; therefore making surface area as a critical factor to determine the availability of catalytic sites. Consequently, heterogeneous catalysis can be improved through the incorporation of improved specific surface area via engineered porosity in a solid catalyst. Hence, new strategies and technologies are continuously being developed for the synthesis and structure-tailoring of high surface area of mesoporous materials.The conventional preparation of ABO 3 involving a hightemperature solid-state reaction of its metal precursors usually results in a low specific surface area [1][2][3]. Therefore, a novel strategy is highly demanded to fabricate porous ABO 3 materials with high surface areas. Recently, this problem has been solved using the close-packed Colloidal Crystal Template (CCT) method for the preparation of three-dimensionally ordered macroporous (3DOM) perovskite. The CCT which are usually formed by ordering monodispersed microspheres poly(methyl methacrylate) (PMMA), polystyrene or silica are always used to replicate the face-centered close-packed array. With PMMA microspheres as template, Arandiyan et al. [9] investigated Au-Pd alloy nanoparticles (1-3 wt%) dispersed on nanohybrid 3DOM La 0.6 Sr 0.4 MnO 3 (LSMO) perovskite catalysts as novel distinctive class of materials and found to exhibit much higher activity than previously reported monometallic counterparts towards methane combustion. They discovered new functionalised hybrid catalysts within the temperature required for emission control. The study not only advanced knowledge in material chemistry, but also leaded to breakthroughs in the area of engineering hybrid to reduce emission and generate environmental benefits.Bimetallic AuPd/3DOM LSMO catalysts with high surface areas for methane oxidation were successfully fabricated (Figure 1). The unique AuPd/3DOM LSMO catalysts exhibit excellent thermal stability and resistance to deactivation by water vapor during methane combustion. These bimetallic catalysts, possessing a unique 3DOM structure and Au-Pd alloy arrangement, giving excellent catalytic activity which was found to be a combined effect of both the support and Au-Pd NPs including: (i) The high surface area, (ii) Richness in adsorbed oxygen, (iii) Oxidized noble metal species on the surface, (iv) Modified electronic structure of the Au-Pd alloy, (v) Low-temperature reducibility, and (vi) Strong interaction between the Au-Pd alloy and the 3DOM support. The distinctive 3DOM structure, stable NP size and electron interaction withi...