Nailing Down Nickel For Electrocatalysis

Electrocatalysis is central to the further development of proton-exchange membrane (PEM) electrolyzers and fuel cells (1), which can operate as compact units for powering homes or vehicles. A single device could both store energy by generating hydrogen during times of electrical surplus and release energy by oxidizing the hydrogen fuel at times of excess demand (see the figure). Today, this goal is best achieved with expensive, noble metal catalysts. However, reversible catalysts based on abundant materials are essential for such devices to have a substantial impact on sustainable energy systems. On page 1384 of this issue, Le Goff et al. (2) report a hydrogen electrode based on nickel, an abundant element, in which the catalyst is immobilized on a carbon nanotube support. This catalyst effects the reversible interconversion between hydrogen ions (H+) and hydrogen (H2) under aqueous conditions, and provides an important initial step toward a practical, non-noble metal hydrogen electrode.