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A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 1 9 1 4 USING ATOMICALLY THIN PLATINUM-GRAPHENE AS FUEL CELL CATALYSTS Researchers at the Georgia Insti- tute of Technology, Atlanta, are using ul- trathin, graphene-supported platinum films to enable fuel cell catalysts with unprecedented catalytic activity and longevity. Platinum is one of the most com- monly used catalysts for fuel cells be- cause of how effectively it enables the oxidation reduction reaction at the cen- ter of the technology. But its high cost has motivated research efforts to find ways to use smaller amounts of it while maintaining the same catalytic activity. Most platinum-based catalytic systems use the metal’s nanoparticles chemically bonded to a support sur- face, where surface atoms of the parti- cles do most of the catalytic work, and the catalytic potential of the atoms be- neath the surface is never utilized as ful- ly as the surface atoms—if at all. To prepare their atomically thin films, the Georgia Tech researchers used a process called electrochemical atomic layer deposition to grow plati- nummonolayers on a layer of graphene, creating samples that had one, two, or three atomic layers. They found that the bond between neighboring platinum atoms in the film essentially combines forces with the bond between the film and the graphene layer to provide rein- forcement across the system. That was especially true in the platinum film that was two atoms thick. Additionally, the new platinum films at that minimum thickness out- performed nanoparticle platinum in the dissociation energy, which is a measure of the energy cost of dis- lodging a surface platinum atom. The measurement suggests such films could make potentially longer-lasting catalyt- ic systems. gatech.edu . SOLAR LEADS GLOBAL INVESTMENTS IN RENEWABLE ENERGY Worldwide investment in renew- able energy capacity is on track to have roughly quadrupled in the past decade, according to the Global Trends in Re- newable Energy Investment 2019 re- port, released ahead of the UN Global Climate Action Summit. Global invest- ment in this sector from 2010 through 2019 is set to hit $2.6 trillion, with more gigawatts of solar power capaciity than any other generation technology. Solar power will have drawn half of the $2.6 trillion in renewable energy investments made over the decade. ENERGY TRENDS The global share of electricity gen- eration accounted for by renewables reached 12.9% in 2018, up from 11.6% in 2017. This avoided an estimated two billion tons of carbon dioxide emis- sions last year alone—a substantial savings given global power sector emis- sions of 13.7 billion tons in 2018. The cost-competitiveness of re- newables has also risen dramatically. The levelized cost of electricity is down 81% for solar photovoltaics since 2009; for onshore wind, it’s down 46%. China has been the biggest inves- tor in renewables capacity over this decade, having committed $758 billion between 2010 and the first half of 2019, with the U.S. second on $356 billion and Japan third on $202 billion. Europe invested $698 billion in renewables ca- pacity over the same period, with Ger- many and the United Kingdom contrib- uting the most. unenvironment.org. Hyundai Motor Co., Fountain Valley, Calif., and Cummins Inc., Columbus, Ind., have entered into a memorandum of understanding to jointly evaluate opportunities to develop and commercialize electric and fuel cell powertrains. The new powertrains are expected to combine Hyundai’s fuel cell systems with Cummins’ electric powertrain, battery, and control technologies. hyundaiusa.com , cummins.com. BRIEF Researchers at Georgia Tech inspect a piece of platinum-graphene catalyst. Courtesy of Allison Carter. Solar power represents more than half of the $2.6 trillon in renewable energy investments in the last decade. Courtesy of UN Environment/FS/BNEF.