S-scheme Bi2O3/CdMoO4 hybrid with highly efficient charge separation for photocatalytic N2 fixation and tetracycline Degradation: Fabrication, catalytic Optimization, physicochemical studies

Abstract

This study employed a deposition-oxidation method to design and synthesize a novel composite photocatalyst of Bi2O3/CdMoO4. A comprehensive investigation was conducted on the morphology, specific surface area, structure, optical properties, and photoelectric chemical properties of the Bi2O3/CdMoO4 composite. The results indicate the dispersion of Bi2O3 nanoparticles on the surface of CdMoO4 polymers, which increases the light absorption and facilitates the photocatalytic reaction. Furthermore, a tight contact between CdMoO4 and Bi2O3 was observed, resulting in the formation of a heterojunction structure at their contact region due to their suitable band positions. Density functional theory calculations and MS analysis revealed the higher work function of CdMoO4 compared to Bi2O3, causing electron drift from Bi2O3 to CdMoO4 and the subsequent formation of a built-in electric field. The presence of this electric field promotes the separation efficiency of electron-hole pairs through an S-scheme mechanism, thereby enhancing the performance of the Bi2O3/CdMoO4 composite in photocatalytic N2 fixation (PNF) reactions. Under simulated sunlight irradiation, the optimal Bi2O3/CdMoO4 catalyst displayed a PNF rate of 323 μmol/L g-1h−1, which was 3.6 and 11.8 times higher than that of pure CdMoO4 and Bi2O3, respectively. The Bi2O3/CdMoO4 composite also exhibited good performance in tetracycline degradation. Electron spin-resonance experiments indicate that hole and superoxide radicals serve as the primary reactive species. These findings offer practical knowledge about the design and synthesis of new S-scheme photocatalysts for PNF and antibiotics removal.