The realization of commercialization of proton electrolyte membrane water splitting technology significantly depends on the anodic electrocatalyst working at a high potential and strong acidic conditions requiring superior oxygen evolution reaction activity and stability. In this work, we devise the construction of ultrasmall Pd@Ir core-shell nanoparticles (5 nm) with atomic layer Ir (3 atomic layers) on carbon nanotubes (Pd@Ir/CNT) as an exceptional bifunctional electrocatalyst in acidic water splitting. Due to the core-shell structure, strain generated at heterointerfaces leads to an upshifted d band center of Ir atoms contributing to a 62-fold better mass activity at 1.63 V vs RHE than commercial IrO2; besides, the electronic hybridization suppresses the electrochemical dissolution of Ir; as a result, robust stability is also achieved. In hydrogen evolution reaction catalysis, Pd@Ir/CNT exhibits a 3.7 times higher mass activity than Pt/C. Furthermore, only 1.7 V is required to reach a water splitting current density of 100 mA cm-2, 251 mV lower than that of Pt/C-IrO2, indicating its superiority in acidic water splitting.
Keywords: core−shell structure; d band center; hydrogen evolution reaction; oxygen evolution reaction; proton electrolyte membrane water splitting.