Polymer Binder Blends Stabilize Alkaline Hydrogen Evolution by Heterogenized Molecular Phen-Based Cobalt Electrocatalysts through Coordination and Environmental Control

Abstract

With the increase in greenhouse gas emissions and their detrimental effect on the environment, there is a push to develop a renewable way to produce H2, a fuel source that has nonharmful byproducts, unlike traditional methods of energy production. Alkaline water electrolysis has seen increasing focus as a viable way to produce H2, but efficient and stable electrocatalysts are required to facilitate this process. Here, a heterogenized Co(II) phenanthroline-based complex for the production of H2 from alkaline water is disclosed. Activity was improved by considering the role of axial Co ligation and the reaction environment created by the polymer binder in the catalyst inks by using variable ratios of Nafion and poly-4-vinylpyridine (P4VP). A ratio of 1:1 Nafion:P4VP was found to have the highest stability, and Co nanoparticle formation was not observed when P4VP was included as part of the binder mixture. The activity and stability enhancement could not be replicated by the addition of molecular pyridine or the use of poly-2-vinylpyridine, which is sterically prevented from coordinating to Co. The increased electrochemical performance caused by the inclusion of Nafion as part of the polymer binder is attributed to a role in mass transfer to and from the Co active site during catalysis, complementing the stabilizing effect of P4VP on the molecular active site.