C15‐Phase Platinum‐Lanthanide Intermetallics for Efficient Hydrogen Evolution: Identifying Lanthanide's Enhanced Mechanism

Abstract Platinum‐Lanthanide (Pt‐Ln) intermetallic compounds (IMCs) are a promising new class of electrocatalytic materials, yet their synthesis remains a significant challenge, and the role of ordered Ln sites in enhancing catalytic performance is not fully understood. Herein, an effective and rapid avenue for synthesizing carbon‐supported C15‐phase Pt 2 Ln IMCs (Ln: Sm, Eu, Gd, and Tb) through Joule heating technology is proposed. The JH‐Pt 2 Ln/C IMCs exhibit excellent electrocatalytic performance toward alkaline hydrogen evolution reaction (HER), in which JH‐Pt 2 Tb/C presents the lowest overpotential of 17 mV at 10 mA cm −2 . The ordered Pt 2 Tb structure offers favorable Pt 2 dimer sites for the desorption of H* intermediates, in contrast to the Pt 3 trimer sites in disordered Pt 2 Tb and pure Pt. The ordered Tb sites play a bifunctional role in HER: i) The oxophilic Tb atoms are in favor of the H 2 O adsorption and dissociation through Tb‐4f‐OH binding; ii) The strong Tb 4f‐Pt 5d orbital hybridization leads to form negatively charged Pt sites, which promotes the desorption of H* intermediates. Furthermore, the anion exchange membrane water electrolyzer equipped with JH‐Pt 2 Tb/C delivers a low voltage of only 1.79 V cell to reach 1 A cm −2 and maintains the stable operation at 1 A cm −2 for over 100 h.