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 Fe_1-yNi_yS₂@Fe_1-xNi_xOOH microplatelets and SrBaNi₂Fe₁₂O₂₂ powders. Meanwhile, we present an electrochemical conditioning approach to engineering the electrochemically active surface area of electrocatalysts, by which the resultant Fe_1-yNi_yS₂@Fe_1-xNi_xOOH microplatelets have a larger electrochemically active surface area after the electrochemical conditioning of the as-synthesized Fe_1-yNi_yS₂ microplatelets using ammonia borane than those obtained after the conventional electrochemical conditioning without ammonia borane, presumably due to the appropriate conversion rate of Fe_1-xNi_xOOH shells.