Ir Nanoparticles Supported on Oxygen-Deficient Vanadium Oxides Prepared by a Polyoxovanadate Precursor for Enhanced Electrocatalytic Hydrogen Evolution.

Developing highly active electrocatalysts is crucial for the application of electrocatalytic water splitting. In this study, we prepared vanadium oxide-graphene carbon nanocomposites (V x O y /C) with abundant defects using a carbon- and oxygen-rich hexavanadate derivative Na 2 [V 6 O 7 {(OCH 2 ) 3 CCH 3 } 4 ] as a precursor without the addition of an extra carbon source. Subsequently, the V x O y /C was used as a catalyst support to load a small amount of Ir, forming the Ir/V x O y /C nanoelectrocatalyst. This catalyst exhibited low hydrogen evolution overpotentials of only 18.90 and 13.46 mV at a working current density of 10 mA cm -2 in 1.0 M KOH and 0.5 M H 2 SO 4 electrolyte systems, outperforming the commercial Pt/C catalysts. Additionally, the catalyst showed excellent chemical stability and long-term durability. This work provides a new strategy for the design and synthesis of highly active electrocatalysts for water splitting.