Minimal Proton Channel Enables H2 Oxidation and Production with a Water-Soluble Nickel-Based Catalyst

• Published in: Journal of the American Chemical Society Vol. 135; no. 49; pp. 18490 - 18496
• Main Authors: Dutta, Arnab, Lense, Sheri, Hou, Jianbo, Engelhard, Mark H, Roberts, John A. S, Shaw, Wendy J
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 11.12.2013; Amer Chemical Soc
• Subjects: amines; amino acids; Catalysis; catalysts; catalytic activity; Chemistry; Chemistry, Multidisciplinary; electrons; energy; ferredoxin hydrogenase; Fourier transform infrared spectroscopy; hydroelectric power; hydrogen; Hydrogen - chemistry; ligands; Magnetic Resonance Spectroscopy; nickel; Nickel - chemistry; oxidation; Oxidation-Reduction; Physical Sciences; Protons; Science & Technology; solar energy; Spectroscopy, Fourier Transform Infrared; Water - chemistry; wind power; PENDANT AMINES; MOLECULAR CATALYSTS; ELECTRON; DESIGN; EVOLUTION; ACIDS; OUTER-COORDINATION SPHERE; HYDROGEN-PRODUCTION; SYSTEMS; ELECTROCATALYSTS
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/ja407826d

Hydrogenase enzymes use first-row transition metals to interconvert H2 with protons and electrons, reactions that are important for the storage and recovery of energy from intermittent sources such as solar, hydroelectric, and wind. Here we present Ni(PCy 2NGly 2)2, a water-soluble molecular electrocatalyst with the amino acid glycine built into the diphosphine ligand framework. Proton transfer between the outer coordination sphere carboxylates and the second coordination sphere pendant amines is rapid, as observed by cyclic voltammetry and FTIR spectroscopy, indicating that the carboxylate groups may participate in proton transfer during catalysis. This complex oxidizes H2 (1–33 s–1) at low overpotentials (150–365 mV) over a range of pH values (0.1–9.0) and produces H2 under identical solution conditions (>2400 s–1 at pH 0.5). Enzymes employ proton channels for the controlled movement of protons over long distancesthe results presented here demonstrate the effects of a simple two-component proton channel in a synthetic molecular electrocatalyst.