Charge‐Deficient PtCu Clusters‐Stabilized Vacancy‐Engineered Mo _4/3 B ₂ T _z MBene Flake Synergistically Boosts Efficient Water Electrolysis

Abstract In this work, a robust method is presented for synthesizing homogeneously distributed, ultrafine PtCu atomic clusters supported on Cu‐modified, vacancy‐engineered Mo 4/3 B 2 T z MBene nanosheets (PtCu AC @Cu‐Mo 4/3 B 2 T z ). The material serves as highly efficient pH‐universal hydrogen evolution reaction (HER) electrocatalyst, which demonstrates impressively low overpotentials of 4 and 15 mV to achieve 10 mA cm −2 in 0.5 M H 2 SO 4 and 1.0 M KOH, respectively, as well as sustained operational stability. Through comprehensive analysis of in situ Raman spectroscopy and density functional theory, it is realizes that Cu incorporation optimizes the electronic configuration of Pt sites and significantly enhances proton transfer and interfacial water activation. In addition, the active metal‐MBene interactions also leads to modulation in the d‐band center of Pt d‐orbitals, fine‐tuning the adsorption energy of H * and reducing the energy barrier for water dissociation, thus promoting H 2 evolution. The practical tests demonstrate high‐performance anion exchange membrane single‐cell stack based on PtCu AC @Cu‐Mo 4/3 B 2 T z(−) ||RuO 2(+) configuration, reaching current densities of 0.5/1.0 A cm −2 at 1.75/1.86 V and stable performance for over 600 h at 0.5 A cm −2 in 1.0 M KOH at 60 °C. This research underscores the importance of active metal‐supported MBene in enhancing catalytic functions and demonstrates the key role of next‐generation MBene‐based hybrid materials as durable support for electrocatalysts.