Fe polarization site in Bi19S27Cl3 promotes near-infrared photocatalytic reduction of nitrate to ammonia

Abstract

To address the issues of weak response in the near-infrared spectral region and slow NO 3 − reduction kinetics of traditional photocatalysts, this paper successfully synthesized a Fe-doped Bi 19 S 27 Cl 3 photocatalyst via a solvothermal method and applied it to the photocatalytic NO 3 − reduction to ammonia synthesis. The effects of Fe introduction on the crystal structure, surface morphology, and photochemical properties of the material were systematically investigated using XRD, HRTEM, XPS, and UV–Vis-NIR spectrophotometry. The results show that the introduction of Fe did not alter the bulk crystal structure of Bi 19 S 27 Cl 3 , but effectively modulated its surface chemical state and photoelectric properties. Under simulated sunlight irradiation, the optimized Fe-Bi 19 S 27 Cl 3 catalyst exhibited excellent photocatalytic ammonia synthesis activity from NO 3 − reduction, achieving an ammonia yield of 253.5 μmol g -1 h −1 , and also exhibited an activity of 105.3 μmol g -1 h −1 and high stability under near-infrared light irradiation. Photoelectrochemical tests confirmed that the introduction of Fe induced efficient interfacial charge migration and effectively suppressed the recombination of photogenerated electron-hole pairs. Based on in-situ infrared spectroscopy analysis, this work delves into the Fe-mediated NO 3 − reduction pathway, revealing the crucial role of Fe in enhancing interfacial charge transport and accelerating multi-electron transfer.