Atomically Dispersed Mn–Ir Sites on 2D Amorphous Carbon Materials Synergistically Boost Electrochemical Overall Water Splitting

Enhancing the activity and durability of noble-metal-based catalysts for overall water splitting is crucial for advancing sustainable energy conversion. In this study, a novel catalyst, PBN-Ir/Mn, is reported, developed through a self-healing process of the polyhexabenzocoronene network (PBN) that incorporates both Mn and Ir atoms. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) and X-ray absorption spectroscopy (XAS) characterizations confirm a unique atomic-scale Ir–Ir–Mn triangular structure on the porous PBN substrate. The synergy between Mn and Ir atoms leads to superior water electrolysis performance, with ultra-low overpotentials of 11 mV for the hydrogen evolution reaction (HER) and 220 mV for the oxygen evolution reaction (OER) at 10 mA cm⁻². PBN-Ir/Mn also achieves outstanding mass activities, reaching 425.92 A mg⁻¹ for HER and 152.28 A mg⁻¹ OER. Moreover, PBN-Ir/Mn demonstrates exceptional durability in overall water splitting, maintaining stable performance over 100 h in a full-cell setup, surpassing commercial benchmarks. Density functional theory (DFT) calculations reveal that Mn doping modifies the d-band center of Ir, reducing the activation energy barriers and significantly enhancing both activity and stability. The high performance and stability of PBN-Ir/Mn, combined with its scalability for gram-scale synthesis, highlight its potential for industrial applications and multifunctional catalysis.