268598 In-Situ X-Ray Absorption Spectroscopy Investigation of a Bifunctional Manganese Oxide Catalyst with High Activities for the Oxygen Reduction and Evolution

Thursday, November 1, 2012: 9:30 AM
317 (Convention Center )
Yelena Gorlin1, Benedikt Lassalle2, Sheraz Gul2, Jesse D. Benck1, Vittal Yachandra2, Junko Yano2 and Thomas F. Jaramillo1, (1)Chemical Engineering, Stanford University, Stanford, CA, (2)Lawrence Berkeley National Laboratory, Berkeley, CA

The development of active catalytic materials for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the major challenges in energy conversion and storage technologies such as fuel cells, metal-air batteries, electrolysis cells, and solar fuel synthesis. To implement strategies for the rational design of catalysts for the ORR and the OER, it is important to improve our understanding of the chemical state and structure of active surfaces under reaction conditions. X-ray absorption spectroscopy (XAS) can be combined with electrochemistry to elucidate properties of catalytic materials in-situ. In our work, we perform in-situ XAS measurements on a bifunctional manganese oxide (MnOx) catalyst with high electrochemical activity for both the ORR and the OER. Previous in-situ XAS studies on active MnOx catalysts have detected the formation of a disordered MnOx with a structure similar to that of birnessite-MnO2 under OER conditions1 and have linked the presence of Mn (III) to high ORR activity in thermally prepared MnOx catalysts.2 Additionally, ex-situ spectroscopy and x-ray diffraction studies have identified a variety of Mn (III) and Mn (IV) oxides as materials with high catalytic activity for either the ORR2-6 or the OER.3,7-9 Our measurements confirmed that different catalytic surfaces form under the oxygen reduction and evolution conditions and identified a distorted Mn3O4structure as an active ORR phase and manganese (III, IV) mixed oxide as an active OER phase.

References

1. Hocking RK, Brimblecombe R, Chang LY, et al. Water-oxidation catalysis by manganese in a geochemical-like cycle. Nat. Chem. Jun 2011;3(6):461-466. 2. Lima FHB, Calegaro ML, Ticianelli EA. Electrocatalytic activity of manganese oxides prepared by thermal decomposition for oxygen reduction. Electrochimica Acta. Mar 2007;52(11):3732-3738. 3. Gorlin Y, Jaramillo TF. A Bifunctional Nonprecious Metal Catalyst for Oxygen Reduction and Water Oxidation. J. Am. Chem. Soc. Oct 2010;132(39):13612-13614. 4. Mao LQ, Sotomura T, Nakatsu K, Koshiba N, Zhang D, Ohsaka T. Electrochemical characterization of catalytic activities of manganese oxides to oxygen reduction in alkaline aqueous solution. J. Electrochem. Soc. Apr 2002;149(4):A504-A507. 5. Cheng FY, Su Y, Liang J, Tao ZL, Chen J. MnO(2)-Based Nanostructures as Catalysts for Electrochemical Oxygen Reduction in Alkaline Media. Chemistry of Materials. Feb 2010;22(3):898-905. 6. Cao YL, Yang HX, Ai XP, Xiao LF. The mechanism of oxygen reduction on MnO2-catalyzed air cathode in alkaline solution. J. Electroanal. Chem. Oct 2003;557:127-134. 7. Zaharieva I, Najafpour MM, Wiechen M, Haumann M, Kurz P, Dau H. Synthetic manganese-calcium oxides mimic the water-oxidizing complex of photosynthesis functionally and structurally. Energy & Environmental Science. Jul 2011;4(7):2400-2408. 8. Morita M, Iwakura C, Tamura H. Anodic characteristics of massive manganese oxide electrode. Electrochimica Acta. 1979;24(4):357-362. 9. El-Deab MS, Awad MI, Mohammad AM, Ohsaka T. Enhanced water electrolysis: Electrocatalytic generation of oxygen gas at manganese oxide nanorods modified electrodes. Electrochem. Commun. Aug 2007;9(8):2082-2087.


Extended Abstract: File Not Uploaded
See more of this Session: In Situ and Operando Spectroscopy of Catalysts I
See more of this Group/Topical: Catalysis and Reaction Engineering Division