Research Information System
XV. International Symposium on Relations Between Homogeneous and Heterogeneous Catalysis, Berlin, Germany, 11 - 16 September 2011, pp.37
While several metal oxides are known to be very effective water oxidation catalyst, they are not feasible economically. By employing a Single Source Precursor (SSP)-approach towards a “bottom- up” fabricated nanomaterial, we want to shift focus to materials composed out of more abundant materials, tailoring their properties towards more effective OER-catalysts.[1] A SSP is a metalorganic compound, containing all elements desired in the final product. This gives acess to unique materials, e.g. with dopant concentrations above the limits of conventional me- thods.[2-3] The precursors used in these experiments are heterobimetallic (Mn/Zn) cubane like gem- diol complexes.[4] The amount of each metal in the complex can be controlled by the stochiometry of the corresponding metal-acetate during the reaction: (4-y)Mn(OAc)2x4H2O + y Zn(OAc)2 + 4 LH2 CH3CN/H2O NaClO4 [Mn4-yZny(LH)4](OAc)2(ClO4)2 Thermodegradation in synthetic air leads to two different phases: A Mn-doped ZnO-Phase (Mn@ZnO) and at higher calcination temperature (Tc) to ZnMn2O4, which grows on the Mn@ZnO particles as a shell. The calcination temperature needed for this phase to occur is lower as the Mn content in the precursor is higher. Fig. 1: Left: Mn@ZnO particles from a) [MnZn3] & b) [Mn3Zn] Tc = 500°C. Right: Oxygen evolvolution in catalytic test The materials prepared from heterobimetallic precursors show activity in an OER Test system. Such activity is not observed for compounds made from homometallic Zn-precursors. This shows the potential of the SSP-approach to tailor materials for the desired task. References [1] M. Walter, E. Warren, J. McKone, S. Boettcher, Q. Mi, E. Santori, N. Lewis, Chem. Rev. (2010), 110, 6446- 6473. [2] Y. Aksu, M. Driess, Angew. Chem. (2009), 121, 7918-7922. N N HO OH = LH2 V. International Symposium on Relations between Homogeneous and Heterogeneous Catalysis Berlin, September 11 to 16, 2011 38 [3] S. Heitz, J.-D- Epping, Y. Aksu, M.Driess, Chem. Mater. (2010), 22, 4563-4571. [4] S. Polarz, M. Driess, Angew. Chem.(2005), 117, 8104-8109.