Mechanistic investigation of B-doping-regulated axial NH2–Fe1B2N2–Mn1B1N2 asymmetric electronic structure for selective 1O2 generation

Synthesis of a B-doped FeMn dual-atom catalyst (DAC), NH 2 –Fe 1 B 2 N 2 –Mn 1 B 1 N 2 . • Regulation of the electronic asymmetry of NH 2 –Fe 1 B 2 N 2 –Mn 1 B 1 N 2 via first-coordination-shell B doping. • B doping induces pronounced local electronic asymmetry and causes d-band shifts. • Improved understanding of the microscopic mechanism of peroxymonosulfate activation over DACs. • Introduction of a general strategy for engineering asymmetric electronic structures in dual-atom catalysts. • Bridging a critical gap between catalyst design and nonradical advanced oxidation processes. Dual-atom catalysts (DACs) are promising for advanced oxidation processes because they inherit the advantages of single-atom catalysts. However, the intrinsic symmetry of their electronic structures limits peroxymonosulfate (PMS) activation and selective nonradical-pathway generation, constraining their practical application. Heteroatom doping in the first coordination shell effectively breaks the electronic symmetry of DACs; however, the mechanism governing selective singlet oxygen ( 1 O 2 ) generation remains unclear. Herein, a B-doped FeMn DAC is synthesized via pyrolysis using boric acid and ZIF-8 as the B and N sources, respectively, to enhance PMS activation and selective 1 O 2 generation. Characterization results and density functional theory calculations reveal that B doping regulates the formation of an axial NH 2 –Fe 1 B 2 N 2 –Mn 1 B 1 N 2 asymmetric electronic structure. In the NH 2 –Fe 1 B 2 N 2 –Mn 1 B 1 N 2 /PMS system, PMS highly selectively adsorbs on the catalyst and coordinates with Mn in a bidentate configuration and Fe serves as an electron-density-regulation center. Through long-range electronic coupling, the active-site electronic structure is optimized. The asymmetric electronic structure considerably enhances antibiotic degradation efficiency in water (97.8%) and increases the reaction rate ( k  = 0.12 min −1 ). Overall, this study precisely regulates the electronic asymmetry of NH 2 –Fe 1 B 2 N 2 –Mn 1 B 1 N 2 through first-coordination-shell B doping, elucidates the synergistic mechanism of dual atoms in targeted 1 O 2 generation, and provides a new perspective for designing asymmetric electronic-structure catalysts for advanced oxidation applications. Download: Download high-res image (112KB) Download: Download full-size image