U.S., SOUTH KOREA SIGN FREETRADE PACT COMMERCE: Agreement could boost U.S. exports to fast-growing Asian market
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HE CHEMICAL INDUSTRY is welcoming a free trade agreement between the U.S. and South Korea, but the measure faces opposition in Congress from Democrats who fear it could cost auto industryjobs. The agreement is the largest trade deal the U.S. has negotiated since the 1993 North American Free Trade Agreement. It would eliminate tariffs on 95% of con sumer and industrial products between the two coun tries within three years. South Korea is among the world's top 10 chemicalproducing countries. Already the sixth-largest market for U.S. chemical exports, which totaled $4.3 billion in 2006, the country is among the fastest growing markets for them in Asia.
LOW-COST CATALYSIS SURFACE SCIENCE: Inexpensive MoS2 mimics precious-metal catalyst
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N WORK that could lead to economical substitutes for precious-metal catalysts, researchers in Den mark have produced hydrogen from water through a reaction catalyzed by a low-cost metal sulfide. The unique surface properties of platinum, rutheni um, and other metals located in the same region of the periodic table endow those materials with the ability to catalyze numerous chemical reactions. They are widely used, for example, in automotive emissions cleanup and fuel-cell processes. Nonetheless, the metals' high cost has long motivated scientists to search for less ex pensive substitutes. Using synthesis methods to control the size and morphology of single-layered, flat molybdenum disul fide nanoparticles, scientists at the Technical Univer sity of Denmark, in Lyngby, have demonstrated that the particles can catalyze the hydrogen evolution reaction (2H+ + 2e" -> H2) in solution (Science 2007,317,100). They also have determined that this reaction occurs
"We are eager to see chemical tariffs in Korea elimi nated as quickly as possible," says American Chemistry Council President Jack N. Gerard. "We are pleased that this agreement includes strong protections for invest ments and intellectual property, as well as important commitments by Korea on regulatory transparency and technical barriers to trade." Officials signed the accord on June 30, hours before President George W. Bush's authority to negotiate "fast track" trade agreements expired. That authority allowed the White House to broker free-trade deals that Con gress must either approve or reject, but cannot change. "This is the most commercially significant trade agreement for the U.S. in nearly 15 years," says Com merce Secretary Carlos M. Gutierrez. Key Democrats, however, contend the measure does not go far enough in dismantling South Korea's nontariff barriers, especially in the automotive industry. Last year, they note, South Korea exported more than 700,000 cars to the U.S., while the U.S. shipped fewer than 5,000 cars there. "Unfortunately, the agreement as currently negoti ated is a missed opportunity," House Speaker Nancy Pelosi (D-Calif.) and other House Democratic leaders say in a joint statement. "We cannot support it as cur rently negotiated."-GLEN Ν HESS
along the perimeter (edge) of the particles, a detail with both theoretical and practical value. The gas-evolution reaction, which lies at the heart of solar-energy-driven hydrogen production via water splitting and runs in reverse in fuel cells, is a prime example of the type of reaction catalyzed by noble met als. Earlier theoretical work suggested that the edges of nanoparticulate MoS2 could catalyze the reaction, but until now that prediction had not been verified conclusively. To prepare the nanoparticles, postdoc Thomas F. Jaramillo, physics professor lb Chorkendorff, and their coworkers used vapor deposition methods and heat treatments to react molybdenum with hydrogen sulfide on a gold surface. Through judicious choice of synthesis conditions, the team was able to control the ex tent of particle sintering and thereby systemati cally vary the particle size and the relative num bers of atoms that reside within the terrace (the open crystal face) and along the nearly atomically thin edge. After analyzing the MoS2 samples using scanning tunneling microscopy, the team measured the particles' catalytic activity in elec trochemical cells and determined that hydrogen evolution correlates linearly with the number of nanoparticle edge sites.-MITCH JACOBY
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JULY 9, 2007
South Korea is one of the 10 largest chemicalproducing countries in the world.
Measuringjust a few nanometers across, these MoS2 particles catalyze hydrogen evolution along their edges.
