(272h) High Performance Non Noble Metal Containing Catalyst for PEM Fuel Cell

Prasad Patel^a,  Moni K. Datta^b, Prashanth Jampani Hanumantha^a, Prashant N. Kumta^{a, b, c, d}

^aDepartment of Chemical and Petroleum Engineering ^bDepartment of Bioengineering

^cDepartment of Mechanical Engineering and Materials Science

^dSchool of Dental Medicine

University of Pittsburgh, Pittsburgh, PA 15261

                The rapid depletion of fossil fuels and increased environmental pollution due to vast fossil-fuel consumption is a major impetus for efficient use of energy and exploration of renewable and clean energy sources [1-3]. Generation of electricity from renewable energy sources, such as solar, wind without producing carbon dioxide-an undesirable green house pollutant, offers enormous potential for meeting future energy demands [4]. Development of novel and efficient technology to store electrical energy is important for facing the global energy demand and environmental concerns. Fuel cell technology has garnered increasing attention as it provides promising and sustainable approach for the production of continuous power with reduced greenhouse gas emissions and higher efficiencies compared to hitherto combustion based technologies. In particular, proton exchange membrane fuel cells (PEMFCs) are considered to be suitable power sources for automobiles, consumer electronic devices and auxiliary power units due to the advantages of using hydrogen as fuel which is light-weight, clean and has a low operating temperature. Hydrogen also offers quick start-up, extended durability of system components, high power density with low weight and volume due to elimination of additional steps needed for fuel reformation. The simple system design would be reflected as an ease in operation, reduced cost and high reliability. However, capital cost of the system is a major constraint limiting commercialization of PEMFCs due to use of expensive Pt/C catalyst. Hence, development of non-noble metal based catalysts with high electrochemical activity and durability is of interest to replace Pt/C and thus, lower the cost of PEMFC system.

                The present study explores (W_xM_1-x)O₃ solid solution as anode electro-catalyst for hydrogen oxidation reaction (HOR) for PEM fuel cell application, where x = 0.7, 0.8. The x-ray mapping shows homogeneous distribution of W, M and O without segregation at any specific site. Electrochemical characterization has been carried out in H₂ saturated 0.5 M sulfuric acid (H₂SO₄) as an electrolyte, Pt wire as counter electrode and Hg/Hg₂SO₄ as the reference electrode (+0.65 V with respect to SHE), using a scan rate of 10 mV/sec and temperature of 40⁰C. The solid solution catalyst (W_0.7M_0.3)O₃ exhibits superior electrochemical activity and stability, similar to Pt/C. In addition, to obtain a better understanding of the fundamental electrochemical activity and long term stability of (W_0.7M_0.3)O₃electro-catalyst, first-principles calculations of the total energies and electronic structures of the model systems with chemical compositions similar to those of the experimentally synthesized materials have been carried out to complement the present experimental study.

                 Results indicate that (W_0.7M_0.3)O₃has the potential for replacing Pt/C, owing to the excellent electrochemical performance and stability. The result obtained to date offers the potential for portending significant reduction in the overall capital costs of PEM fuel cell systems. Results of the structural characterization and electrochemical activity of this novel electro-catalyst will be presented and discussed.

References:

1. Liu, C., et al., Advanced Materials for Energy Storage. Advanced Materials, 2010. 22(8): p. E28-E62.
2. Miller, J.R., Valuing Reversible Energy Storage. Science, 2012. 335(6074): p. 1312-1313.
3. Peng, B. and J. Chen, Functional materials with high-efficiency energy storage and conversion for batteries and fuel cells. Coordination Chemistry Reviews, 2009. 253(23–24): p. 2805-2813.
4. Whittingham, M.S., Materials challenges facing electrical energy storage. MRS Bull., 2008. 33(4): p. 411-419.