Synthesis of 2D NiFe2O4 nanoplates/2D Bi2WO6 nanoflakes heterostructure: An enhanced Z-scheme charge transfer and separation for visible-light-driven photocatalytic degradation of toxic pollutants

Water pollution is a worldwide concern due to excessive discharge of toxic contaminants to water streams. Effective treatment of organic pollutants in wastewater by utilizing visible-light is a promising method to resolve environmental problems. In the present work, we have demonstrated a facile one-step hydrothermal strategy for the synthesis of a binary NiFe 2 O 4 /Bi 2 WO 6 heterostructured nanocomposite. Further, the utility towards photocatalytic degradation of tetracycline (TC) and methylene blue (MB) has been evaluated. The characterization results revealed that the two-dimensional (2D) Bi 2 WO 6 nanoflakes were inserted upon 2D NiFe 2 O 4 nanoplates, which enhanced the interfacial contact and improved visible-light absorption efficiency, resulting in excellent photogenerated charges separation and transfer. The NiFe 2 O 4 /Bi 2 WO 6 heterostructured nanocomposite exhibited higher TC degradation (96.81%) in 96 min and MB degradation (99.16%) in 60 min than the pure samples and remained stable for four successive cycles. The apparent reaction rate constant ( k ) of 20 mg loading of Bi 2 WO 6 over NiFe 2 O 4 (NFBW-20) exhibited the best photocatalytic performance among the all prepared materials, which was 7.15 (TC) and 9.19 (MB) times that of pristine Bi 2 WO 6 , and 6.02 (TC) and 6.41 (MB) times that of pure NiFe 2 O 4 . Radical trapping experiments confirmed •O 2 − , and •OH radicals were critical active species in the degradation mechanism, which supports the Z-scheme photocatalytic mechanism. Mott–Schottky measurements were used determine the positions of the conduction and valence bands of the samples, and a possible photocatalytic mechanism for TC and MB degradation was proposed according to experimental results. This study offers a novel effective avenue to design efficient binary heterostructured nanocomposites with superior visible-light response for environmental remediations. • Hydrothermally prepared Bi 2 WO 6 nanorods were inserted on NiFe 2 O 4 nanoplates. • The charge-transfer pathway followed a Z-scheme mechanism. • The nanocomposite degraded 96.81% of TC and 99.16% of MB under visible-light. • Strong interfaces and charge separation improved the performance of 2D/2D heterostructure.