Enhancing Photoreduction of Cr(VI) through a Multivalent Manganese(II)-Organic Framework Incorporating Anthracene...

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Photocatalytic reduction of hexavalent chromium (Cr(VI)) is essential for environmental remediation.
• Developing stable and highly active photocatalysts under mild conditions remains a significant challenge.

Purpose of the Study:

• To synthesize and characterize a novel two-dimensional manganese-based metal-organic framework (MOF), LCUH-120.
• To evaluate the photocatalytic efficiency of LCUH-120 for Cr(VI) reduction.

Main Methods:

• Coordination of a rigid aromatic multicarboxylate ligand (anthracene) with manganese ions.
• Characterization of the resulting two-dimensional (2D) Mn-based MOF (LCUH-120).
• Photocatalytic reduction experiments of Cr(VI) under visible light irradiation in an acidic environment.

Main Results:

• LCUH-120 was successfully synthesized as a stable 2D Mn-based MOF.
• Complete reduction of Cr(VI) to Cr(III) was achieved in 40 minutes using LCUH-120 as a photocatalyst without additional photosensitizers.
• The photocatalytic reaction exhibited a high rate constant (k = 0.134 min⁻¹) and reduction rate (2.50 mgCr(VI) g⁻¹cata min⁻¹) at pH 2.
• LCUH-120 demonstrated significantly higher catalytic activity compared to a previously reported 3D Sm-MOF.

Conclusions:

• LCUH-120 is a highly efficient and stable photocatalyst for Cr(VI) reduction.
• The anthracene moiety acts as a photosensitizer and Mn(II) ions as the catalytic center.
• Enhanced electron transfer and charge separation in LCUH-120 contribute to its superior photocatalytic performance.