Abstract 

A sandwich-type polyoxometalate, K₄Na₇[(α-SiFe₃W₉(OH)₃O₃₄)₂(OH)₃].56H₂O (POM-Fe), was successfully synthesized and investigated as an efficient electrocatalyst for nitrite reduction. Its chemical composition was confirmed by energy-dispersive X-ray fluorescence (EDXRF), energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA), while structural features were elucidated using single-crystal and powder X-ray diffraction, complemented by IR and UV–Vis spectroscopy. Magnetic measurements revealed paramagnetic behavior with a saturation magnetization of 0.0646 emu g⁻¹. The electrocatalytic performance of POM-Fe toward nitrite reduction was evaluated by cyclic voltammetry at pH 4.8 and 3. revealing a remarkable catalytic efficiency at pH 4.8. Overall, these results demonstrate the strong potential of POM-Fe for environmental remediation and electrocatalytic applications.