Interfacial engineering of 2D/2D/2D g-C3N4/Ti3C2/SnS2 ternary heterojunction for enhanced visible-light-driven photocatalytic removal of Cr(VI) and tetracycline

Highly efficient charge migration and separation are critical for the design of high-efficiency and stable photocatalysts. In our work, novel 2D/2D/2D g-C 3 N 4 /Ti 3 C 2 /SnS 2 heterojunctions were successfully prepared via a simple hydrothermal route combined with electrostatic self-assembly strategy. Compared to single-component (g-C 3 N 4 , SnS 2 ) and binary composite materials (g-C 3 N 4 /SnS 2 , g-C 3 N 4 /Ti 3 C 2 ), the optimized ternary g-C 3 N 4 /Ti 3 C 2 /SnS 2 composite displayed significantly enhanced photocatalytic efficiency and higher kinetic rate constants for the elimination of Cr(VI) and tetracycline (TC). More interestingly, further improved photocatalytic performance was achieved when the composite catalyst was applied to the mixed Cr(VI)/TC pollutant system, with the reaction rate constants being 1.46-fold and 1.06-fold higher than those of single Cr(VI) and single TC systems, respectively. Finally, a Z-scheme charge migration pathway was proposed in the 2D layered g-C 3 N 4 /Ti 3 C 2 /SnS 2 heterojunction, which enabled the expedited electron transfer between g-C 3 N 4 and SnS 2 with Ti 3 C 2 as an electron mediator and boosted the charge separation efficiency. The present work provides a viable way for constructing 2D/2D/2D Z-scheme heterojunction photocatalytic materials, offering great potential for the treatment of complex pollutants in wastewater.