Starch hydrogel-loaded cobalt nanoparticles for hydrogen production from hydrolysis of sodium borohydride

Sanoe Chairam, Purim Jarujamrus and Maliwan Amatatongchai

Abstract

In this work, starch hydrogel was successfully prepared using a citric acid cross-linking method and then was utilized in the preparation of starch hydrogel-loaded cobalt nanoparticles (CoNPs) by the reduction of Co²⁺ ions loaded within the starch hydrogel network. The swelling behavior of starch hydrogel as a function of temperature and pH was also investigated. The resulting hydrogel-loaded CoNPs were confirmed using a number of techniques including powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and thermogravimetric analysis (TGA). The activity of starch hydrogel-loaded CoNPs was evaluated by employing them as a catalyst for the hydrogen production from the hydrolysis of sodium borohydride (NaBH₄). The activation energy (E _a ) was 52.18 kJ mol⁻¹; whereas, the activation enthalpy (ΔH ^#) and activation entropy (ΔS ^#) were 49.54 kJ mol⁻¹ and −138.61 kJ mol⁻¹, respectively. The activity of starch hydrogel-loaded CoNPs maintained over the 5 cycles of utilization. Due to its biocompatibility, flexibility and nontoxicity, starch hydrogel could be considered as a promising candidate to be used as a template for the preparation of metal nanoparticles in the hydrogen production and even in catalysis of other reactions