IrCo Nanoparticles Encapsulated with Carbon Nanotubes for Efficient and Stable Acidic Water Splitting

The acidic water-splitting technology based on the polymerexchangemembrane can produce hydrogen efficiently, continuously, and cleanly,which is expected to alleviate the energy crisis. However, even noblemetal-based electrocatalysts such as IrO x species would dissolve rapidly during acidic oxygen evolution. Herein,we successfully assemble high-density carbon nanotubes (CNTs) encapsulatedwith IrCo nanoparticles (NPs) on carbon cloth (IrCo@CNT/CC) usinga facile MOF-templated and dicyandiamide-assisted pyrolysis strategy.Benefiting from the favorable synergistic effect between Co and Irand the protection of CNT, the obtained IrCo@CNT/CC only requiresa low cell voltage of 1.500 V to reach 10 mA cm(-2) for water splitting with an extremely low Ir loading of 0.027 mgcm(-2) and exhibits robust stability under continuouselectrolysis for 90 h in 0.5 M H2SO4, rankingit among one of the best bifunctional electrocatalysts for acidicwater splitting. Detailed experiments reveal that the CNT-encapsulatedIrCo NPs in IrCo@CNT/CC remain after the hydrogen evolution reaction(HER) but transform into Co-doped IrO2 NPs after the oxygenevolution reaction (OER). Further DFT simulation calculations confirmthat the Co doping in Ir and IrO2 can optimize their electronicstructures to lower their energy barriers for HER and OER, respectively.