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2,2’-Dipyridylamine as Organic Molecular Electrocatalyst for Hydrogen Evolution Reaction in Acidic Electrolytes
preprintsubmitted on 17.06.2019, 16:18 and posted on 18.06.2019, 15:40 by Xi Yin, Ling Lin, Hoon T. Chung, Ulises Martinez, Andrew M. Baker, Sandipkumar Maurya, Piotr Zelenay
Finding a low-cost and stable electrocatalyst for hydrogen evolution reaction (HER) as a replacement for scarce and expensive precious metal catalysts has attracted significant interest from chemical and materials research communities. Here, we demonstrate an organic catalyst based on 2,2’-dipyridylamine (dpa) molecules adsorbed on carbon surface, which shows remarkable hydrogen evolution activity and performance durability in strongly acidic polymer electrolytes without involving any metal. The HER onset potential at dpa adsorbed on carbon has been found to be less than 50 mV in sulfuric acid and in a Nafion-based membrane electrode assembly (MEA). At the same time, this catalyst has shown no performance loss in a 60-hour durability test. The HER reaction mechanisms and the low onset overpotential in this system are revealed based on electrochemical study. Density functional theory (DFT) calculations suggest that the pyridyl-N functions as the active site for H adsorption with a free energy of -0.13 eV, in agreement with the unusually low onset overpotential for an organic molecular catalyst.