Z-Scheme MIL-53(Fe)/Mn-SrTiO₃ heterostructure for efficient photocatalytic degradation of o-nitrophenol

With growing concerns over water pollution and depletion of freshwater resources, finding sustainable and cost-effective solutions for water treatment is crucial. This study introduces a novel MIL-53(Fe)/Mn-doped SrTiO₃ (MIL-53(Fe)/Mn-STO) direct Z-scheme photocatalyst, designed to efficiently degrade organic contaminants in water. Specifically, the photocatalytic degradation of o-nitrophenol (ONP) was investigated under an Xe lamp. The MIL-53(Fe)/Mn-STO photocatalyst demonstrated a maximum removal efficiency of 97.75% within 90 min, with a rate constant (k) of 0.0374 min^-1, outperforming the individual MIL-53(Fe) and Mn-STO photocatalysts. A comprehensive analysis of the material's properties was conducted using Fourier transform Infrared spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, diffuse reflectance spectroscopy and photoluminescence techniques, and the photocatalytic activity was evaluated under various conditions, including variations in pH, ONP concentration, catalyst dosage and the presence of inorganic anions. The improved photocatalytic activity of the MIL-53(Fe)/Mn-STO system can be ascribed to the synergistic interaction between its two components, which also contributed to its excellent recyclability over five cycles. These findings demonstrate that MIL-53(Fe)/Mn-STO is a highly effective and sustainable photocatalyst with a strong potential for wastewater treatment applications.