Fabrication of a Bi/Bi ₂ WO ₆ Ohmic Junction to Enhance Interfacial Charge Transfer for the Removal of Cr(VI), Tetracycline, and Methylene Blue

Bi-embedded Bi 2 WO 6 ohmic junction photocatalysts (Bi-BWO) were synthesized via a one-step direct hydrothermal route or hydrothermal method followed by in situ reduction using different reductants. The Bi (N) -BWO prepared via an in situ reduction pathway using NaBH 4 showed better physicochemical and photocatalytic redox performances than the Bi-BWO via a direct hydrothermal route using glucose or ascorbic acid as a reductant. The Bi-BWO displayed an enhanced photocatalytic redox activity in Cr(VI) reduction and tetracycline (TC)/methylene blue (MB) degradation under visible light, which was ascribed to the synergy of the ohmic junction and localized surface plasmon resonance (LSPR) of Bi nanoparticles (Bi NPs). The Bi (N) -BWO provided the highest removal efficiencies with 93.4% Cr(VI) and 77.0% TC removal rates for 120 min, whose reaction rates were 4.5- and 2.5-fold higher than those of the pristine Bi 2 WO 6, respectively. Notably, the Bi (N) -BWO exhibited a superior simultaneous removal efficiency of Cr(VI)/TC with the reaction rates of 85.4 × 10 –3 for Cr(VI) and 16.4 × 10 –3 min –1 for TC, which are separately 4.0- and 1.4-fold higher than those in the single Cr(VI) and TC systems, respectively. This work provides a feasible approach to improve the photocatalytic performances of bismuth-based catalysts in wastewater remediation.