Trifunctional fishbone-like PtCo/Ir enables high-performance zinc−air batteries to drive the water-splitting catalysis

Abstract

Precise tuning of the geometric and electronic structure of Pt- or Ir-based nanomaterials is pivotal for the development of highly efficient catalysts for the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER). Indeed, alloying Pt or Ir with a single metal can modulate the d-band center of the metal for better catalytic performance. However, such a strategy usually leads to single-functional high-performance nanocatalysts. Herein, we report a new class of Pt-rich PtCo/Ir-rich IrCo trimetallic fishbone-like nanowires (PtCo/Ir FBNWs) with tailored surface/interface structure for achieving remarkable trifunctional catalytic properties effectively tuned by d-band pinning and offsetting with morphological and compositional controls. Through such a metallic hetero-d-band-junction mechanism, the optimal multifunctional performance has been robustly pinned via precise ternary alloying ratios. Particularly, as-made Pt62Co23/Ir15FBNWs exhibit outstanding electrocatalytic activities for HER and OER in both acidic and alkaline solutions, exceeding that of commercial Pt/C or Ir/C, respectively. The overall water-splitting devices driven by Pt62Co23/Ir15 FBNWs are applicable in a wide pH medium, which has achieved the current density of 10 mA cm-2 in the acid electrolyte at a low potential of 1.53 V, 23.3 times higher than that of Pt/C-Ir/C. Notably, the ORR performance of Pt62Co23/Ir15 FBNWs also maintains a higher level than Pt/C, which makes FBNWs usable in high-performance zinc-air batteries to drive the water-splitting in a self-powered manner. Theoretical calculations reveal that their superior multifunctional catalytic activities can be attributed to the unique morphologically induced interfacial stress, which can facilitate an effective combination of d-band pinning and offsetting for dynamic self-activations among HER, OER, and ORR catalysis.