Engineering of Highly Active Silver Nanoparticles for Oxygen Electroreduction via Simultaneous Control over Their Shape and Size

The oxygen reduction reaction (ORR) is one of the most important electrocatalytic reactions, which requires efficient and economically viable electrocatalysts. While Pt(Pd)-based catalysts show the best ORR performance for automotive applications, their use in large-scale industrial processes, for instance at the oxygen depolarized cathodes in chloralkali industry, is questionable due to the high cost of Pt(Pd). Silver, being much more affordable than platinum, is known as the “second-active” ORR electrocatalyst in alkaline media. Shape-selected Ag nanoplates of three different sizes are synthesized using a one-step bottom-up approach. With no alloying, optimal Ag nanoplates show specific activity of ≈2.6 mA cm⁻² (3 times higher than Ag (110)) and mass activity of (Formula presented.) (6.5 times higher compared to state-of-the-art Ag nanospheres) toward ORR at 0.8 V versus reversible hydrogen electrode. These activities are the highest reported in the literature for pure Ag electrocatalysts (both single crystalline and nanostructured) measured under similar conditions.