Mn-Mo-Sn Oxide Anodes for Oxygen Evolution in Seawater Electrolysis for Hydrogen Production A. A. El-Moneim a , J. Bhattarai b , Z. Kato c , K. Izumiya d , N. Kumagai d and K. Hashimoto c a Department of Materials Science and Engineering, Egypt-Japan University of Science and Technology, New Borg El Arab, Alexandria, Egypt b Central Department of Chemistry, Tribhuvan University, Kathmandu, Nepal c Tohoku Institute of Technology, Sendai, 982-8577 Japan d Daiki Ataka Engineering Co. Ltd., Kashiwa, Chiba, 227-8515 Japan For hydrogen production by seawater electrolysis the anodic reaction should be oxygen evolution without forming chlorine. The durability of anode was significantly extended by determining factors influencing the lifetime in preparation of the electrocatalysts and by improving the intermediate layer preventing oxidation of the titanium substrate in the anode. The electrocatalysts for durable anode should not be too thin and too thick. The specific resistance of deposit affected the thickness of electrocatalysts deposited anodically. Mo 6+ increases the specific resistance while W 6+ and Sn 4+ decrease it. The best composition of the electrolyte for preparation of Mn 1-x-y Mo x Sn y O 2+x electrocatalyst was determined on the basis of the roles of additive elements. The lifetime was significantly extended by repetitive deposition for 30 min three times with washing and drying of the anode and renewing of the electrolyte at every intermission. The intermediate layer consisting of Sn 1-x-y Ir x Sb y O 2+0.5x instead of IrO 2 prevented effectively oxidation of titanium. INTRODUCTION For prevention of global warming and for prevention of complete exhaustion of fossil fuels and uranium, renewable energy origin fuels should be supplied to meet the demand of the whole world. We are proposing global carbon dioxide recycling for the use of renewable energy. Intermittent electricity generated by solar cell in deserts will be converted to hydrogen by seawater electrolysis at nearby desert coasts, and hydrogen with no infrastructures of transportation and combustion will be converted to methane by the reaction with carbon dioxide. Methane is the same as natural gas for which there exist efficient infrastructures of transportation and combustion. Key materials necessary for this process are the anode and cathode for seawater electrolysis and the catalyst for conversion of carbon dioxide into methane. We have been creating these key materials. For production of enormous amount of fuel, enormous amount of chlorine evolution, which generally occurs on the anode in seawater electrolysis, is not allowed. Thus in spite of seawater electrolysis, the reaction on the anode should not be chlorine evolution but be oxygen evolution. ECS Transactions, 25 (40) 127-137 (2010) 10.1149/1.3422589 ©The Electrochemical Society 127 Downloaded 27 Apr 2010 to 130.207.50.90. Redistribution subject to ECS license or copyright; see http://www.ecsdl.org/terms_use.jsp