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Hydrogen gas offers one of the most promising sustainable energyalternatives to limited fossil fuels. But traditional methods ofproducing pure hydrogen face significant challenges in unlockingits full potential, either by releasing harmful carbon dioxide intothe atmosphere or requiring rare and expensive chemical elementssuch as platinum. Now, scientists at the U.S. Department of Energy's (DOE) BrookhavenNational Laboratory have developed a new electrocatalyst thataddresses one of these problems by generating hydrogen gas fromwater cleanly and with much more affordable materials. The novel form of catalytic nickel-molybdenum-nitride - describedin a paper published online May 8, 2012 in the journal AngewandteChemie International Edition - surprised scientists with itshigh-performing nanosheet structure, introducing a new model foreffective hydrogen catalysis. "We wanted to design an optimal catalyst with high activity and lowcosts that could generate hydrogen as a high-density, clean energysource," said Brookhaven Lab chemist Kotaro Sasaki, who firstconceived the idea for this research. "We discovered this excitingcompound that actually outperformed our expectations." Goldilocks chemistry Water provides an ideal source of pure hydrogen - abundant andfree of harmful greenhouse gas byproducts. The electrolysis ofwater, or splitting water (H2O) into oxygen (O2) and hydrogen (H2),requires external electricity and an efficient catalyst to breakchemical bonds while shifting around protons and electrons. To justify the effort, the amount of energy put into the reactionmust be as small as possible while still exceeding the minimumrequired by thermodynamics, a figure associated with what is calledoverpotential. For a catalyst to facilitate an efficient reaction, it must combinehigh durability, high catalytic activity, and high surface area.The strength of an element's bond to hydrogen determines itsreaction level - too weak, and there's no activity; too strong, andthe initial activity poisons the catalyst. "We needed to create high, stable activity by combining onenon-noble element that binds hydrogen too weakly with another thatbinds too strongly," said James Muckerman, the senior chemist wholed the project. "The result becomes this well-balanced Goldilockscompound - just right." "We needed to introduce another element to alter the electronicstates of the nickel-molybdenum, and we knew that nitrogen had beenused for bulk materials, or objects larger than one micrometer,"said research associate Wei-Fu Chen, the paper's lead author. "Butthis was difficult for nanoscale materials, with dimensionsmeasuring billionths of a meter." The scientists expected the applied nitrogen to modify thestructure of the nickel-molybdenum, producing discrete, sphere-likenanoparticles. But they discovered something else. Subjecting the compound to a high-temperature ammonia environmentinfused the nickel-molybdenum with nitrogen, but it alsotransformed the particles into unexpected two-dimensionalnanosheets. The nanosheet structures offer highly accessiblereactive sites - consider the surface area difference between bedsheets laid out flat and those crumpled up into balls - andtherefore more reaction potential. Using a high-resolution transmission microscope in Brookhaven Lab'sCondensed Matter Physics and Materials Science Department, as wellas x-ray probes at the National Synchrotron Light Source, thescientists determined the material's 2D structure and probed itslocal electronic configurations. "Despite the fact that metal nitrides have been extensively used,this is the first example of one forming a nanosheet," Chen said."Nitrogen made a huge difference - it expanded the lattice ofnickel-molybdenum, increased its electron density, made anelectronic structure approaching that of noble metals, andprevented corrosion." Hydrogen future The new catalyst performs nearly as well as platinum, achievingelectrocatalytic activity and stability unmatched by any othernon-noble metal compounds. "The production process is both simpleand scalable," Muckerman said, "making nickel-molybdenum-nitrideappropriate for wide industrial applications." While this catalyst does not represent a complete solution to thechallenge of creating affordable hydrogen gas, it does offer amajor reduction in the cost of essential equipment. The teamemphasized that the breakthrough emerged through fundamentalexploration, which allowed for the surprising discovery of thenanosheet structure. "Brookhaven Lab has a very active fuel cell and electrocatalysisgroup," Muckerman said. "We needed to figure out fundamentalapproaches that could potentially be game-changing, and that's thespirit in which we're doing this work. It's about coming up with anew paradigm that will guide future research." Additional collaborators on this research were: Anatoly Frenkel ofYeshiva University, Nebojsa Marinkovic of the University ofDelaware, and Chao Ma, Yimei Zhu and Radoslav Adzic of BrookhavenLab. The research was funded by Brookhaven's Laboratory DirectedResearch and Development (LDRD) Program. The National SychrotronLight Source and other Brookhaven user facilities are supported bythe DOE Office of Science. Scientific Paper: "Hydrogen-Evolution Catalysts Based on Non-Nobel MetalNickel-Molybdenum Nitride Nanosheets". We are high quality suppliers, our products such as Educational Laboratory Equipment Manufacturer , China Smart Teaching System for oversee buyer. 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