Peony-Structured ZIF-8-Infused Lyophilized Hydrogel as a High-Performance Bifunctional Electrocatalyst for Hydrogen Peroxide Fuel Cells and Its Electrochemical Detection in Tap Water Samples

The development of flexible, multifunctional materials capable of simultaneously serving as electrocatalysts and electrochemical sensors remains limited, especially in integrated platforms. This work reports the synthesis and characterization of ZIF-8 (Zeolitic Imidazolate Framework) formed by the coordination of 2-methylimidazole with Zn 2+ in a hydrogel matrix and highlights its dual potential for energy conversion and sensing applications. The ZIF-8-infused hydrogel is synthesized through the coprecipitation method, followed by freeze-drying to obtain a PVA (Poly(vinyl alcohol))-based hydrogel. The SEM analysis reveals peony-structured morphology, while the XRD patterns confirm the crystalline nature of ZIF-8 embedded within the hydrogel matrix. When explored as an electrocatalyst for Hydrogen Peroxide (H 2 O 2 ) Fuel cells, the hydrogel exhibits a high current density of 1.4 A/g and good stability. As a sensor for Hydrogen Peroxide (H 2 O 2 ) detection, this fabricated sensor demonstrates a linear range of detection from 0.01 to 10 mM, with a 0.02 mM lower limit of detection. This dual functionality, as an electrocatalyst for H 2 O 2 fuel cells and as a sensitive and selective sensor for H 2 O 2 detection in complex matrices like tap water, opens up avenues for multifunctional materials in the field of sustainable energy and electrochemical analysis.