Polyallylamine-Functionalized Platinum Tripods: Enhancement of Hydrogen Evolution Reaction by Proton Carriers

Tailoring the size, controlling the morphology, and designing the metal–organic interface are three promising strategies to improve the catalytic performance of monometallic noble-metal nanocrystals. In the "hydrogen economy" society, water electrolysis is viewed as one of the most promising technologies for hydrogen production. The design and synthesis of highly active and durable electrocatalysts for the hydrogen evolution reaction (HER) is vitally important for the development of the hydrogen economy. In this work, we successfully synthesized polyallylamine (PAA)-functionalized Pt tripods (Pttripods@PAA) with ultrathin and ultralong branches through a facile chemical reduction method in an aqueous solution of PAA. The morphology, structure, and composition of Pttripods@PAA were fully investigated by various physical techniques. The characterization results reveal that ultrathin and ultralong branches of Pttripods@PAA have a concave structure with high-index facets and that PAA strongly binds on the Pt surface as a proton carrier. Impressively, Pttripods@PAA display unexpected activity for the HER in acidic solution with an onset reduction potential of +19.6 mV vs RHE, which significantly outperforms currently reported monometallic Pt electrocatalysts. This activity is due to the increase in the local proton concentration on the Pt surface.