IrW nanobranches as an advanced electrocatalyst for pH-universal overall water splitting

Developing highly efficient and durable electrocatalysts for overall water splitting over a wide pH range is of great interest for practical applications, but still remains a challenge. Specifically, to the best of our knowledge, a 3-in-1 electrocatalyst that can efficiently catalyze overall water splitting in acidic, alkaline, and neutral electrolytes has not been reported so far. Herein, we report the colloidal synthesis of well-dispersed IrW nanobranches with branch architectures and describe how the morphology varies with the amount of W doping. As expected, they exhibit outstanding catalytic performance and durability for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at all pH values, which are much higher than those of Ir nanoparticles (NPs), and most reported state-of-the-art electrocatalysts. More importantly, when further used as both an anode and cathode for overall water splitting in 0.1 M HClO4, 0.1 M KOH, and 1.0 M PBS (phosphate buffer solution), cell voltages of 1.58, 1.60, and 1.73 V, respectively, were achieved at a current density of 10 mA cm-2. The present work opens up a new avenue for designing electrocatalysts for pH-universal overall water splitting, especially for application in highly corrosive acidic media and neutral media with limited ionic concentrations.