Dr. Masahiro Watanabe, who has a strong belief in the importance of promoting basic science that is tied to the eventual return of the results to Society, has contributed to the development of advanced materials and mechanistic studies for various types of fuel cells, based on unique, innovative concepts. His important achievements are introduced in the following brief overview.

1. Development of catalysts for direct methanol fuel cells (DMFCs)
DMFCs are attractive due to their high volumetric power density, but they have been plagued by large potential losses at the anode, even for Pt, which has the highest activity among pure, elemental catalysts. Dr. Watanabe started systematic studies on a series of precious metal alloys and their catalysis. He discovered that in the classification of alloying components into relatively active A-type metals (Pt, Ir, Pd, Rh, etc.) and inert B-type metals (Ru, Os, Re, etc.), AB alloys exhibit a noticeable enhancement, with an optimum composition of about 1:1 for methanol oxidation, and AA alloys simply showed a dilution effect. He proposed the well-known "Bifunctional Mechanism" for the catalysis, in which both A and B atoms contribute to the enhancement by playing different roles in the reaction scheme and generalized the theory by extending it to several types of "Electrocatalysis by Adatoms" as a convenient tool for new catalyst development. The preparation of nanoscale Pt-Ru particles supported on carbon black (CB), invented by him, and their catalytic performance have been widely referred to by many scientists and engineers, and the same catalyst has been uniquely applied to both commercial DMFCs and polymer electrolyte fuel cells (PEFCs) in residential cogeneration systems.

2. Development of less-expensive Pt-alloy catalysts for anode/cathode
High tolerance is needed versus catalyst poisoning by CO remaining in reformed H₂ fuel for the Pt anode catalyst for commercial PEFCs. On the other hand, management of the improvement of cathode performance and the reduction of Pt loading at the cathode are essential, because the O₂ reduction reaction (ORR) is much slower than the H₂ oxidation reaction (HOR), by several orders of magnitude, and it is responsible for ca. 80% of the total energy loss in the cells. Dr. Watanabe has discovered that superior CO tolerance, up to ca. 100 ppm CO, for the HOR can be achieved with alloys between non-precious transition metals such as Fe, Co, Ni, etc., with precious metals such as Pt, Pd, Rh, etc., by lowering the CO adsorption strength and coverage on their surfaces. The alloys exhibit a positive core-level shift in the Pt 4f binding energy, which is inversely proportional to the Pt-CO bonding energy, and vice versa at non-CO tolerant alloys. Thus, a guiding principle for the development of CO tolerant anode catalysts was established. On the other hand, he also discovered an enhanced ORR activity at Pt alloyed with Co, among others, which is more than one order of magnitude at their optimum compositions of 30-50% non-precious metal, in comparison with pure Pt. By efficient and unique application of electrochemical methods (EC) together with modern experimental systems such as quartz crystal microbalance (EC-QCM), scanning tunneling microscopy (EC-STM) or X-ray photoelectron spectroscopy (EC-XPS), he has clarified that the alloys mentioned above are covered with a "Pt skin" consisting of 1-2 atomic layers, which are modified in their electronic structure by that of the underlying alloy, resulting in the noticeable enhancement of ORR mentioned above. These discoveries of bimetallic catalysts and mechanisms of him have sparked the recent active R&D on "Core-Shell Catalysts" all over the world.

3. Development of highly dispersed catalysts and their performance
The reduction of Pt loadings to less than 1/10 of the presently used level, corresponding to the amounts used for the treatment of exhaust gases from internal combustion engine (ICE) cars, i.e., 10 g Pt/100 kW, is essential for the wide penetration of fuel cell electric vehicles (FCEVs) into the market. Dr. Watanabe has aimed to overcome this difficult hurdle, i.e., the increase of the mass activity MA, which is proportional to the specific surface area S and the specific area activity J, by nanosizing (to ca. d = 2nm in diameter) and alloying (as mentioned above) of the advanced catalysts. He has proposed an original "Territory Theory" and demonstrated experimentally that there is no reduction in the MA caused by the so-called "Particle Size Effect," even at d = 2nm, as long as the intercrystallite distance is maintained at larger than ca. 15 nm on the support substrate, resulting in the MA being observed to actually increase proportionally to the increased S-value. Based on the above results, he has invented a "Nanocapsule Method" for the preparation of nanosize pure and alloy catalysts, which are controlled strictly in the size, composition and dispersion state on the support materials and has been demonstrating their extremely high performance and durability, in comparison with widely used commercial catalysts, in a large national project, in cooperation with several materials and systems companies.
Furthermore, Dr. Watanabe has invented "Self-Humidifying Polymer Electrolyte Membranes (PEMs)" utilizing dispersed highly hygroscopic nanosize metal oxides and/or Pt nanoparticles. The membranes make it possible to operate a PEFC without humidification, leading to system simplification and cost reductions, particularly for FCEVs. Through this work, he has ignited extensive worldwide R&D on this concept. On the other hand, he has developed hydrocarbon-type PEMs in his group, which are environmentally friendly and have a large cost reduction potential. He has already demonstrated single PEFC operations for 5,000 h with these advanced PEMs. For H₂ production/purification, he has been doing superior work in the development of heterogeneous catalysts for the reforming of hydrocarbon fuels, the reformate shift-reaction, and the preferential oxidation or selective methanation of CO remaining in the reformate.
As mentioned above, he has contributed distinctively to the development of advanced materials for fuel cells and the clarification of related phenomena. His achievements are rated very highly world-wide. Accordingly, it was recently decided that his achievements merit the Chemical Society of Japan (CSJ) Award.