Hexadecyltrimethylammonium hydroxide promotes electrocatalytic activity for the oxygen evolution reaction.

The oxygen evolution reaction is an essential factor in many renewable energy technologies, such as water splitting, fuel cells, and metal-air batteries. Here we show a unique solution to improve the oxygen evolution reaction rate by adjusting the electrolyte composition via the introduction of hexadecyltrimethylammonium hydroxide into an alkaline electrolyte. The strong adsorption of hexadecyltrimethylammonium cations on the surface of electrocatalysts provides the increased absolute number of OH ions near the electrocatalyst surface, which effectively promotes the oxygen evolution reaction performance of electrocatalysts, such as FeNiS@FeNiOOH microplatelets and SrBaNiFeO powders. Meanwhile, we present an electrochemical conditioning approach to engineering the electrochemically active surface area of electrocatalysts, by which the resultant FeNiS@FeNiOOH microplatelets have a larger electrochemically active surface area after the electrochemical conditioning of the as-synthesized FeNiS microplatelets using ammonia borane than those obtained after the conventional electrochemical conditioning without ammonia borane, presumably due to the appropriate conversion rate of FeNiOOH shells.