The electronic structure precision of single-atom catalysts (SACs) represents a decisive factor limiting advancements in photocatalytic nitrogen reduction (NRR) efficiency. This study addresses this issue by simultaneously introducing an axial fluoride ligand (F-) and engineering surface oxygen vacancies (Ov) around atomically dispersed Bi centers supported on W18O49 (denoted as FBWO). The axial fluoride ligand withdraws electron density away from the Bi site, increasing surface hydrophobicity and forming a surface dipole. This dipole lowers the conduction band while promoting side-on N2 chemisorption. Meanwhile, photo-induced Ov accumulate electrons around Bi site, forming a continuous F-Bi-Ov "electron pump" that reduces the activation energy for the first proton-electron transfer from 1.69 eV (on pristine W18O49 with single Bi sites, BWO) to 0.87 eV (on FBWO). These synergistic electronic and energetic modifications enable the material to achieve a visible-light NH3 production rate of 354.2 µmol g-1·h-1-8.4 times that of pristine W18O49 and twice that of BWO-surpassing all recently reported Bi- and W-based photocatalysts for N2 reduction. This work provides a unified design strategy that integrates ligand-field engineering with defect chemistry, facilitating the targeted development of SACs into high-performance photocatalysts for sustainable ammonia production.″.
Ge et al. (Sat,) studied this question.