Strong Electronic Coupling between Ultrafine Iridium–Ruthenium Nanoclusters and Conductive, Acid-Stable Tellurium Nanoparticle Support for Efficient and Durable Oxygen Evolution in Acidic and Neutral Media

Abstract

Proton exchange membrane water electrolysis (PEM-WE) has emerged as a promising technology for hydrogen production and shows substantial advantages over conventional alkaline water electrolysis. To enable efficient PEM-WE in acidic media, iridium (Ir)- or ruthenium (Ru)-based catalysts are indispensable to drive the thermodynamically and kinetically demanding oxygen evolution reaction (OER). However, developing Ir/Ru catalysts with high efficiency and long-term durability still remains a formidable challenge. Herein, we report one-pot hydrothermal synthesis of ultrafine IrRu intermetallic nanoclusters loaded on conductive, acid-stable, amorphous tellurium nanoparticle support (IrRu@Te). Benefiting from the large exposed electrocatalytically active surface of ultrafine IrRu clusters and the strong electronic coupling between IrRu and Te support, the as-obtained IrRu@Te catalysts show good catalytic performance for the OER in strong acidic electrolyte (i.e., 0.5 M H2SO4), requiring overpotentials of only 220 and 303 mV to deliver 10 and 100 mA cm–2 and able to sustain continuous OER electrolysis up to 20 h at 10 mA cm–2 with minimal degradation. Moreover, IrRu@Te exhibits high specific activity, illustrating intrinsically better performance compared with that of unsupported IrRu and other commercial Ir- and Ru-based catalysts. It also demonstrates unprecedentedly high mass activity of 590 A gIrRu–1 at an overpotential of 270 mV, outperforming most Ir- and Ru-based OER catalysts reported in the literature. Furthermore, IrRu@Te catalysts reveal good OER performance in neutral electrolyte as well, holding great potential to be used for PEM-WE in environmentally friendly conditions. Density functional theory (DFT) calculations based on oxidized IrRu confirm that the catalyst/support coupling results in a lower energy barrier for the oxygen–oxygen bonding formation, offering a rational explanation to the experimentally observed OER performance.