In situ synthesis of α-Fe2O3/LaFeO3 modified with g-C3N4 and Ti3C2 for construction of multiple Z-scheme/Schottky heterojunctions as an efficient visible-light photocatalyst for Cr (VI) reduction and organic pollutants removal

Abstract

We report an in situ synthesis of α-Fe2O3/LaFeO3 compounded with g-C3N4 and Ti3C2 MXene to form multiple Z-scheme/Schottky heterojunctions, α-Fe2O3/LaFeO3/g-C3N4 /Ti3C2 (FLCT). In FLCT, α-Fe2O3/LaFeO3 promoted carrier migration, g-C3N4 caused electrons to move directionally toward Ti3C2, inhibiting the carrier complex, and the Ti3C2 substitution of a noble metal provided more adsorption active sites and promoted carrier separation. The synergistic effect of the multiple Z-scheme/Schottky heterojunctions endowed the FLCT composite with an excellent photocatalytic performance. To demonstrate the extensive applicability of the composite materials in the photocatalytic degradation and reduction of wastewater, methylene blue (MB), rhodamine B (Rh B), tetracycline hydrochloride (TC), and hexavalent chromium ions (Cr (VI)) were used as model pollutants; 91.30% of the MB, 84.32% of the Rh B, and 76.11% of the TC were photocatalytic degraded. In addition, 79.60% of the Cr (VI) was photocatalytically reduced by FLCT. These results showed that the composite catalyst exhibited photocatalytic degradation or reduction efficiencies that were 3.41-, 3.86-, 5.44-, and 4.14-fold greater than those of pure LaFeO3 for MB, Rh B, TC, and Cr (VI), respectively. The intrinsic relationship between the composite structure and the photocatalytic performance was investigated to reveal the enhancement mechanism of the composite photocatalytic performance. The charge migration path and pollutant degradation mechanism in the photocatalytic system were elucidated. This work provides a novel concept for designing heterojunction-structured photocatalysts and provides an experimental foundation for photocatalytic technology to treat water pollution.