Rational design of Z-scheme LaFeO3/SnS2 hybrid with boosted visible light photocatalytic activity towards tetracycline degradation

Visible-light-driven photocatalytic degradation of organic pollutants is considered as one of the promising and effective strategies for water purification. Extensive efforts have been devoted to explore various inorganic and organic semiconductor materials as photocatalysts for the degradation of organic pollutants under visible light irradiation in the past few decades. Among them, artificial Z-scheme photocatalyst has recently attracted considerable attention in water purification owing to it can not only effective transfer and separation of the photogenerated charge carriers, but also retain prominent redox ability. Herein, a direct Z-scheme LaFeO3/SnS2 hybrid was successfully constructed via a facile hydrothermal method. The structure, composition, photoelectric and photocatalytic properties of the as-obtained samples were systematically characterized by X-ray diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, transient photocurrent response, electrochemical impedance spectroscopy and photocatalytic degradation of tetracycline (TC). These characterizations revealed that the LaFeO3 nanoparticles were well dispersed on the surface of SnS2 nanosheets. The photoelectrochemical characterizations demonstrated that the promoted transfer and separation of charge carrier in the LaFeO3/SnS2 hybrid was achieved. As expected, compared to bare LaFeO3 and SnS2, all the LaFeO3/SnS2 hybrids displayed boosted the photocatalytic performances for the degradation of TC under visible light irradiation (λ > 420 nm). In particular, the photocatalytic degradation of TC over all the as-obtained samples obeyed pseudo-first-order kinetics equation, and the optimal photodegradation rate constant over the LaFeO3(10.0 wt%)/SnS2 hybrid for TC degradation was up to 0.0028 min−1, which was about 3.5 and 2.2 times larger than those of SnS2 and LaFeO3, respectively. Such an enhancement could be mainly ascribed to the formation of the Z-scheme LaFeO3/SnS2 heterojunction, which not only promoted the visible light absorption, but also facilitated the charge separation and transfer efficiency and prolonged lifetime of charge carriers as a result of the closely contacted Z-scheme heterojunction interface effect between LaFeO3 and SnS2. Furthermore, results from the radical trapping experiments confirmed that there existed the Z-scheme charge transfer mechanism, and the synergistic effect of superoxide radicals and holes was favorable for the photodegradation of TC under visible light irradiation. This work will provide a new insight for the rational design and construction of highly efficient SnS2-based Z-scheme heterojunction hybrid photocatalysts for applying in environmental remediation and energy conversion.