High-density growth of ultrafine PdIr nanowires on graphene: reducing the graphene wrinkles and serving as efficient bifunctional electrocatalysts for water splitting

Manipulating the distribution states, exposed surfaces, and interfacial interactions of graphene-based nanomaterials is a key issue for taking full advantages of graphene characteristics. Herein we report the in-suit plantation of numerous ultrafine PdIr alloy nanowires (diameter of 1.8 nm) to predominately cover the whole surface of graphene (PdIr UNWs/WFG). The high density but low atom loading (8.6 at%) of PdIr nanowires give rise to abundant edge atoms and rough surface, which are beneficial for the full exposure of active sites. Meanwhile, compact PdIr overlay endows strong surface tension to stretch the graphene wrinkles, thus averting the wrap of active sites and ensuring the structural uniformity. The PdIr UNWs/WFG are qualified for efficient and robust electrocatalysts on both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), affording 10 mA cm-2 at HER overpotential of 23 mV and 10 mA cm−2 at OER overpotential of 290 mV, respectively. The corresponding water electrolyzer requires a cell voltage of only 1.51 V to achieve water-splitting current of 10 mA cm-2. This simple and novel approach to command the coordinated form, dispersion state, and interfacial tension is promising to be a versatile method for improving the properties of graphene-based nanomaterials.