Mechanical Catalysis || Time-Dependent (“Mechanical”), Nonbiological Catalysis. 2. Highly Efficient,“Biomimetic” Hydrogen-Generating Electrocatalysts

✍ Scribed by Swiegers, Gerhard F.

• Publisher: John Wiley & Sons, Inc.
• Year: 2008
• Tongue: English
• Weight: 932 KB
• Edition: 1
• Category: Article
• ISBN: 0470262028
• DOI: 10.1002/9780470384190.ch12

✦ Synopsis

The two-electron reduction of inorganic acids (H þ ) to hydrogen gas (H 2 ) is efficiently catalyzed by the hydrogenase enzymes in biology [1]. However, the best nonbiological, heterogeneous catalyst is Pt metal, which serves as the universal standard for electrochemical potentials in the Normal Hydrogen Electrode (NHE). A longstanding research goal in the catalysis of multielectron redox processes involving small gaseous molecules like O 2 , H 2 , and N 2 has been to discover molecular catalysts whose activity exceeds that of the best available heterogeneous catalyst and approaches that of the relevant enzymes [2].

The formation of H 2 from H þ involves several steps, including the uni-atomic reduction step (H þ þ e 2 ! H † ) in which atomic hydrogen is formed. On metal surfaces, this step is highly unfavorable (E8 ca. 22.10 V for Pt) [2]. Two H † species must also find each other on the metal surface in order to form H 2 . An overpotential is, therefore, required to drive the reaction.