Ni-Doped Bi ₂ MoO ₆ /In ₂ O ₃ Z-Scheme Heterojunctions for Simultaneous Photocatalytic Cr(VI) Reduction and Emerging Organic Contaminant Degradation

Element doping has attracted extensive attention as a strategy to regulate the electronic structure of catalysts. In this study, Ni-doped Bi 2 MoO 6 nanosheets were uniformly anchored onto rod-like In 2 O 3 to furnish substantial accessible reactive sites and close interfacial contact. Ni doping enabled a precise modulation for the band configuration of Bi 2 MoO 6, imparting a Z-scheme heterojunction between Ni-doped Bi 2 MoO 6 and In 2 O 3 . The Ni-doped Bi 2 MoO 6 /In 2 O 3 Z-scheme heterojunction exhibits excellent photocatalytic performance in the treatment of Cr(VI) and emerging organic contaminants. In the Cr(VI)/bisphenol A coexistence system, Ni-doped Bi 2 MoO 6 /In 2 O 3 not only achieved high reduction efficiency for Cr(VI), but also enhanced the degradation rate of bisphenol A by a factor of 4.7 compared to the single-pollutant system. The removal efficiencies could surpass many related reported studies. The product toxicity after bisphenol A degradation in a mixed Cr(VI)/bisphenol A system was analyzed by the total organic carbon content, high-performance liquid chromatography-tandem mass spectrometry, the toxicity estimation software tool, and microbial activity, manifesting that their impact on the environment has been greatly reduced. Furthermore, the catalyst maintains stable and consistent performance in multiple binary systems, including Cr(VI)/tetracycline and Cr(VI)/ciprofloxacin. This work provides insights for the design of element-doped heterojunction catalysts, which demonstrate high performance, durability, and environmental compatibility in the treatment of complex wastewater.