Noble Metal-P-Block-Element Intermetallics with d-p Orbital Hybridization for Highly Efficient Electrocatalysis

Abstract

Alloying is a widely accepted strategy for modulating the electronic structure of noble metal-based electrocatalysts and reducing the consumption of noble metals. The d-p orbital hybridization generated by alloying noble metals with p-block elements is favorable for enhancing the catalytic performance. Unlike the fabrication of solid solution alloys, the construction of intermetallic compounds (IMCs) can efficiently utilize the orbital hybridization effect originating from the ordered heteroatom bonding, meanwhile improving the stability of the catalysts due to the more negative formation enthalpy. In this work, a series of noble metal-p-block-element IMCs is synthesized by using a solid-state grinding method combined with a thermal annealing process. Among them, Ir3Sn7 IMCs supported on the commercial carbon (denoted as Ir3Sn7/C) with a low-iridium-loading of 13.60% emerge as excellent electrocatalysts for overall water splitting in a wide pH range, exhibiting low operating cell voltages and remarkable stability in long-term measurements. Density functional theory (DFT) calculations further demonstrate that the existence of the strong d-p hybridization interaction between Ir and Sn atoms can optimize the surface electronic structure of Ir3Sn7/C, thereby improving the electrocatalytic performance.