Modulation in the electronic structure of Ir-rich shell on AuIr solid solution as OER electrocatalyst for PEM electrolyzer

The design of low-cost and high-performance anodic electrocatalyst is essential in proton exchange membrane water electrolysis (PEMWE) application. Herein, we design and synthesize a core–shell structure with Ir-rich shell and AuIr alloy core by using a simple liquid phase reduction method, which exposed a large number of active sites. The d-band center of Ir active sites, merely 2 nm in size, was shifted by the electronegativity difference between the Au and Ir atoms at the core–shell interface. The strong electronic effect can inhibit the dissolution and corrosion of Ir active sites under acidic and high potential conditions. As a result, Irx@Au0.25Ir0.75−x catalyst shows merely 235 mV overpotential at the current density of 10 mA cm−2, 75 mV lower than the commercial Ir black catalyst, and 2.6-fold higher mass activity than the commercial Ir black catalyst. Furthermore, when Irx@Au0.25Ir0.75−x was used as the anionic catalyst, the electrolysis voltage at 1 A cm−2 is 1.7 V in PEMWE, and this activity was maintained for more than 100 h and had exhibited excellent stability, indicating its ideal prospects as an electrocatalyst. AuIr alloy with Ir-rich core and AuIr alloy shell exposed numerous active sites and improved the utilization efficiency of electrocatalyst.