Hydrogen‐Bubble Repellent Conjugated Polymeric Coating for Improving Electrochemical Hydrogen Evolution.

Abstract For gas‐forming electrochemical reactions, such as the hydrogen evolution reaction (HER), the unavoidable adhesion of the produced gas bubbles to the electrode often compromises the access of the electrolyte to the catalytically active sites and the subsequent electron transfer processes, overall perturbing the performance of the electrochemical reaction. To address this important challenge, a few extremely bubble repellent coatings have been introduced in the recent past — but at expense of diminished electrochemically active surface areas and reaction kinetics. Here, a metal‐free, robust coating on nickel foam (NF) following electro deposition of a single component, i.e., polyglycerol‐modified pyrrole, without incurring any wastage is introduced. The polyglycerol moiety ensures extreme gas‐bubble repellence due to low bubble adhesion forces, permitting the early detachment of produced hydrogen gas bubbles. On the other side, the conjugated polypyrrole chain facilitates the electron transfer process within and through the coating. These synergistic attributes enable HER with a reduced overpotential (28% at 100 mA cm −2 ), a smaller Tafel slope (84.2 vs 100.8 mV dec −1 ), and an increased electrochemically active surface area by 104% as compared to the underlying bare NF electrode.