Engineering continuous charge steps in multiple 2D-semiconductor hetero-interface for rapidly photocatalytic dye-degradation and disinfection

Abstract

The development of inexpensive and high-efficient semiconductor photocatalysts is of great significance for achieving the goal of environmental remediation. However, the fast recombination of the photoinduced charge-carriers in semiconductor photocatalysts still poses a huge obstacle. In this contribution, we pave “continuous charge steps” in multiple 2D-semiconductor hetero-interface through an orderly assembly of 2D semiconductors of g-C3N4, SnS2, and TiO2 nanosheets (NSs) by using a facile ultrasonic dispersion and subsequent heat treatment. The matchable energy band structures between the above three 2D NSs allows their orderly composite (g-C3N4/SnS2/TiO2 NSs) to possess two kinds of broad 2D hetero-interface configurations (g-C3N4/SnS2/TiO2 and TiO2/g-C3N4/SnS2) with the extended light-harvesting range. The time-resolved photoluminescence spectroscopy results prove that both of the above hetero-interface configurations could induce the formation of “continuous charge steps” to accelerate the interfacial electron transfer. Thus, upon UV–visible light irradiation, the as-synthesized g-C3N4/SnS2/TiO2 NSs exhibited 4.2–7.5 fold enhancement for the photocatalytic degradation of Rhodamine B. Notably, the photocatalytic disinfection efficiency of the g-C3N4/SnS2/TiO2 NSs for Escherichia coli could be over 99.99% after simulated sunlight irradiation for only 30 min. This study opens up a new path for sensible design of ternary heterostructure photocatalyst with continuous charge steps towards an extraordinary photocatalytic activity.