SnO2/SnS2 nanocomposite anchored on nitrogen-doped RGO for improved photocatalytic reduction of aqueous Cr(VI)

Nitrogen-doped reduced graphene oxide (NRG)/SnO2/SnS2 ternary photocatalyst was fabricated by hydrothermal methods in two steps. XRD, Raman, XPS, X-ray elemental mapping, TEM and HRTEM analyses verified the preparation of NRG/SnO2/SnS2 ternary nanocomposite. The photocurrent response, photoluminescence, electrochemical impedance and electron spin resonance measurements indicated that the three components had synergistic effects in decreasing the carrier recombination of NRG/SnO2/SnS2. For photocatalytic reduction of aqueous Cr(VI) under visible-light irradiation, the photocatalytic efficiency of NRG/SnO2/SnS2 was higher than those found for SnS2, binary composites (NRG/SnO2, NRG/SnS2 and SnO2/SnS2), and other reported ternary photocatalysts (g-C3N4/SnS2/SnO2, SnS2-BiFeO3/rGO, NRG/SnS2/PANI and SnS2/SnO2/CPVC). Moreover, NRG/SnO2/SnS2 also exhibited a high efficiency in photocatalytic treatment of the diluted black chromium electroplating solution. Based on the results of comparative photocatalytic experiments in N-2 or air atmosphere, and with or without O-2(center dot-) trapping agent (p-Benzoquinone), it was inferred that Cr(VI) was reduced dominantly by photogenerated electrons of NRG/SnO2/SnS2. (c) 2020 Elsevier B.V. All rights reserved.