Electrochemical Growth of Metallic Nanoparticles onto Immobilized Polymer Brush Ionic Liquid as a Hybrid Electrocatalyst for the Hydrogen Evolution Reaction.

Platinum and palladium are the first choice electrocatalysts to drive the hydrogen evolution reaction. In this report, surface modification was introduced as a potential approach to generate hybrid electrocatalyst. The immobilized polymer brush, poly(1-allyl-3-methylimidazolium) (PAMI), was used as a nanostructured template for guiding the electrochemical deposition of metallic nanoparticles (Pd, Pt). The intrinsic properties of the polymer brush in term of nanostructured architecture and the anions mobility within the polymer was exploited to generate a hybrid electrocatalyst. The latter was generated using two different approaches including the direct electrochemical deposition of Pd or Pt metal and the indirect approach through the anion exchange reaction followed by the electrochemical deposition under self-electrolytic conditions. The hybrid structure based on the polymer/metallic NP exhibits an enhancement of the catalytic performance toward hydrogen evolution reaction with a low Tafel slope and overpotential. Interestingly, the indirect approach leads to decrease the metal loading by two orders of magnitude, when compared to those generated in the absence of the polymeric layer, while retaining the electrocatalytic performance.