Facile and environmentally friendly synthesis of highly efficient two-dimensional hematene nanosheets for photocatalytic applications

Exfoliation of bulk hematite (α-Fe₂O₃), as an environmentally friendly, nontoxicity, and low-cost semiconductor oxide, exhibited greater photocatalytic activity under visible light irradiation. Herein, we described two preparation methods of novel two-dimensional non-van der Waals hematene (2D-Hm) nanosheets including ultrasound-assisted liquid-phase exfoliation (US-Hm) and chemical-assisted liquid-phase exfoliation (CH-Hm). The photocatalytic activity of 2D-Hm nanosheets was evaluated for the decomposition of Tetracycline (TC). Various advanced analyses were used to investigate the physical and chemical properties of the exfoliated samples. SEM and TEM analyses confirmed the layered structures of 2D-Hm. The crystalline structure of 2D-Hm samples was confirmed successfully by XRD analyses. After exfoliation of bulk hematite, the surface area increased remarkably from 5.73 m²/g to 24.16, and 15.26 m²/g using US-Hm, and CH-Hm exfoliation methods, respectively. The photoelectrochemical photocurrent and electrochemical impedance spectroscopy (EIS) analysis indicate that 2D-Hm samples have higher charge-transfer efficiency than bulk hematite. Additionally, the formation of hydroxyl (^•OH) radicals was approved using the o-phenylenediamine (OPD) and photoluminescence (PL) analysis. The leaching iron concentration in the aqueous phase was measured within five consecutive examinations. To recognize the intermediates formed during the degradation process, gas chromatography-mass spectrometry (GC–MS) was employed.