In the short term, focus should be placed on achieving higher energy efficiency and increasing supplies from all forms of renewable energy. At the same time remediation and preservation of our environment is mandatory [1]. Nanomaterials are now beginning to play an important role in answering some of the challenges presented by energy and environment. In this context, understanding and controlling the materials properties is of paramount importance for the materials chemist. Optimized synthesis methods with higher efficiency are required in order to have a sustainable production of targeted materials with improved properties. Perovskite-type materials have been gaining increasing importance in the last 20 years, due to their interesting structural and functional properties [2]. In particular, perovskite-type materials with the ABO3 structure have been deeply investigated as electrodes and electrolytes materials for solid oxide fuel cells and as catalysts. Solution combustion synthesis (SCS) is a versatile method for the efficient synthesis of nanomaterials [3,4]. The basis of the SCS technique comes both from the thermo-chemical concepts used in the field of propellants and explosives and from the concepts of the sol-gel chemistry. The essential ingredients of the SCS are four: fuel, oxidant, metal precursors and initiation (Figure 1). The number of parameters which could be controlled is very large, so that many variants to the method are possible. In this talk, four variants are discussed and applied to the preparation of perovskite-type materials. 1. Citric acid (CA)-aided SCS. High purity nanostructured cathode materials with complex chemical composition can be produced by CA-SCS (Figure 2), if some important processing parameters are carefully controlled. The cases of Sr1-xCexFeO3-?, La0.6Sr0.4Co0.95Fe0.05O3-?, and BaCe0.9Gd(Y)0.1O3-? are here discussed. 2. Mixed-Fuel (MF)-aided SCS. Cathode materials with low area specific resistance and high oxygen deficiency are prepared by MF-SCS. The case of Ba0.5Sr0.5Co0.8Fe0.2O3-? is here discussed. 3. The Soft-Hard Templating (SHT) approach. High surface area catalysts are prepared by using the SHT approach (Figure 3). The SHT approach can be viewed as a variant of the solution combustion synthesis, where an auto-combustion process between the fuel and the metal nitrates occurs in the presence of a silica hard template (ie.: amorphous silica, HMS or SBA-15). The case of LaFeO3 is here discussed. 4. Bio-Organic Substances (BOS)-aided SCS. Mesoporous catalysts with high sustainability are obtained by BOS-SCS (Figure 4), where BOS are derived from organic urban wastes. The BOS have surfactant properties and variable impurities and chemical composition. For this reason each different batch need to be carefully characterized before use. The case of La1-xCaxFeO3-? is here discussed. References 1.M.A. Rosen, I. Dincer and M. Kanoglu, Energy Policy, 36 (2008) 128. 2.A.S. Bhalla, R. Guo and R. Roy, Mater. Res. Innovations, 4 (2000) 3. 3.A.S. Mukasyan, P. Epstein and P. Dinka, Proc. Comb. Inst., 31 (2007) 1789; A.K. Tyagi, S.V. Chavan, and R.D. Purohit, Ind. J. Pure Appl. Phys., 44 (2006) 113. 4.F. Deganello, G. Marcì and G. Deganello, J. Eur. Ceram. Soc., 29 (2009) 439.
Solution Combustion Synthesis of Perovskite-type Materials for Energy and Environment
F Deganello
2012
Abstract
In the short term, focus should be placed on achieving higher energy efficiency and increasing supplies from all forms of renewable energy. At the same time remediation and preservation of our environment is mandatory [1]. Nanomaterials are now beginning to play an important role in answering some of the challenges presented by energy and environment. In this context, understanding and controlling the materials properties is of paramount importance for the materials chemist. Optimized synthesis methods with higher efficiency are required in order to have a sustainable production of targeted materials with improved properties. Perovskite-type materials have been gaining increasing importance in the last 20 years, due to their interesting structural and functional properties [2]. In particular, perovskite-type materials with the ABO3 structure have been deeply investigated as electrodes and electrolytes materials for solid oxide fuel cells and as catalysts. Solution combustion synthesis (SCS) is a versatile method for the efficient synthesis of nanomaterials [3,4]. The basis of the SCS technique comes both from the thermo-chemical concepts used in the field of propellants and explosives and from the concepts of the sol-gel chemistry. The essential ingredients of the SCS are four: fuel, oxidant, metal precursors and initiation (Figure 1). The number of parameters which could be controlled is very large, so that many variants to the method are possible. In this talk, four variants are discussed and applied to the preparation of perovskite-type materials. 1. Citric acid (CA)-aided SCS. High purity nanostructured cathode materials with complex chemical composition can be produced by CA-SCS (Figure 2), if some important processing parameters are carefully controlled. The cases of Sr1-xCexFeO3-?, La0.6Sr0.4Co0.95Fe0.05O3-?, and BaCe0.9Gd(Y)0.1O3-? are here discussed. 2. Mixed-Fuel (MF)-aided SCS. Cathode materials with low area specific resistance and high oxygen deficiency are prepared by MF-SCS. The case of Ba0.5Sr0.5Co0.8Fe0.2O3-? is here discussed. 3. The Soft-Hard Templating (SHT) approach. High surface area catalysts are prepared by using the SHT approach (Figure 3). The SHT approach can be viewed as a variant of the solution combustion synthesis, where an auto-combustion process between the fuel and the metal nitrates occurs in the presence of a silica hard template (ie.: amorphous silica, HMS or SBA-15). The case of LaFeO3 is here discussed. 4. Bio-Organic Substances (BOS)-aided SCS. Mesoporous catalysts with high sustainability are obtained by BOS-SCS (Figure 4), where BOS are derived from organic urban wastes. The BOS have surfactant properties and variable impurities and chemical composition. For this reason each different batch need to be carefully characterized before use. The case of La1-xCaxFeO3-? is here discussed. References 1.M.A. Rosen, I. Dincer and M. Kanoglu, Energy Policy, 36 (2008) 128. 2.A.S. Bhalla, R. Guo and R. Roy, Mater. Res. Innovations, 4 (2000) 3. 3.A.S. Mukasyan, P. Epstein and P. Dinka, Proc. Comb. Inst., 31 (2007) 1789; A.K. Tyagi, S.V. Chavan, and R.D. Purohit, Ind. J. Pure Appl. Phys., 44 (2006) 113. 4.F. Deganello, G. Marcì and G. Deganello, J. Eur. Ceram. Soc., 29 (2009) 439.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
