Optimization of Intercalated 2D BiOCl Sheets into Bi2WO6 Flowers for Photocatalytic NH3 Production and Antibiotic Pollutant Degradation

Photocatalytic N2 fixation is a complex reaction, thereby prompting researchers to design and analyze highly efficient materials. Herein, one-pot hydrothermal Bi2WO6–BiOCl (BW–BiOCl) heterojunctions were synthesized by varying the molar ratio of tungsten: chlorine precursor. Major morphological transformations in BiOCl were observed wherein it turned from thick sheets ∼230 nm in pure BiOCl to ∼30 nm in BW–BiOCl. This was accompanied by extensive growth of {001} facets verified from X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) analyses. A p–n heterojunction was formed between Bi2WO6 and BiOCl evidenced via photoluminescence (PL), time-resolved photoluminescence (TRPL), photocurrent response, and electrochemical impedance spectroscopy (EIS) analyses. The formation of heterojunction between Bi2WO6 and BiOCl led to the reduction of the work function in the BW–BiOCl 0.25 hybrid confirmed via ultraviolet photoelectron spectroscopy (UPS) analysis. BW–BiOCl 0.25 could produce ammonia up to 345.1 μmol·L–1·h–1 owing to the formation of a robust heterojunction with an S-scheme carrier transport mechanism. Recycle tests resulted in no loss in N2 reduction activities with post-catalytic analysis, showcasing the high stability of the synthesized heterojunction. Novel performance was owed to its excellent chemisorption of N2 gas on the heterojunction surface verified by N2-temperature programmed desorption (TPD). BW–BiOCl 0.25 also displayed a superior rate constant of 3.03 × 10–2 min–1 for 90 min CIP degradation time, higher than pristine BiOCl and Bi2WO6. Post-photocatalytic Fourier transform infrared (FTIR) spectroscopy of BW–BiOCl 0.25 revealed the presence of C–H stretching peaks in the range of 2850–2960 cm–1 due to adsorbed CIP and methanol species in CIP degradation and N2 fixation, respectively. This also confirmed the enhanced adsorption of reacting species onto the heterojunction surface.