Abstract
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 Fe1−yNiyS2@Fe1−xNixOOH microplatelets and SrBaNi2Fe12O22 powders. Meanwhile, we present an electrochemical conditioning approach to engineering the electrochemically active surface area of electrocatalysts, by which the resultant Fe1−yNiyS2@Fe1−xNixOOH microplatelets have a larger electrochemically active surface area after the electrochemical conditioning of the as-synthesized Fe1−yNiyS2 microplatelets using ammonia borane than those obtained after the conventional electrochemical conditioning without ammonia borane, presumably due to the appropriate conversion rate of Fe1−xNixOOH shells.
Highlights
The oxygen evolution reaction is an essential factor in many renewable energy technologies, such as water splitting, fuel cells, and metal–air batteries
Intriguingly, we discover that incorporation of hexadecyltrimethylammonium hydroxide (HTAH) into the alkaline electrolyte increases the current density (j) of the oxygen evolution reaction (OER) for Fe1−yNiyS2@Fe1−xNixOOH by a factor of >4 at overpotential (η) of 320 mV, with peak activity at 0.02 M HTAH, relative to solely inorganic alkaline electrolyte
The enhancement effects of HTAH on the OER activity can be extended to other anodic electrocatalysts, such as Y-type hexaferrite powders, which can cure the adverse effects of their low electrochemically active surface area (ECSA)
Summary
The oxygen evolution reaction is an essential factor in many renewable energy technologies, such as water splitting, fuel cells, and metal–air batteries. The iR (i, current; R, series resistance derived from the impedance measurements)-corrected polarization curves in Fig. 3a and Supplementary Fig. 11a illustrate that the Fe1−yNiyS2@Fe1−xNixOOH/NF exhibits a much better catalytic activity than the Fe1−yNiyS2-ECC/NF, Fe1−yNiyS2/ NF, and RuO2/NF benchmark in both electrolytes because the OER on the former requires a lower η than the later three ones at the same j, especially at a large j.
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