Preparation of Co–CaCO3 catalysts for improved hydrogen production from sodium borohydride

Abstract

Ca1-xCoxCO3 nanoparticle catalysts (x = 0.0, 0.1, 0.2 and 0.3 %) were prepared by the sol-gel method. The samples were characterized using various techniques such as X-ray diffraction (XRD), attenuated total reflectance spectroscopy (ATR), environmental scanning electron microscopy (ESEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analysis. The XRD peaks of Ca1-xCoxCO3 displayed a significant level of conformity with the rhombohedral calcite structure. The average crystal size of Ca1-xCoxCO3 nanoparticles was found to be 14 nm. The ESEM micrographs of Ca1-xCoxCO3 showed rhombic calcite shapes. The most prominent peaks in the XPS spectra of Ca1-xCoxCO3 are the Ca 2p, C 1s, Co 2p and O 1s peaks. The sample Ca1-xCoxCO3 has the highest surface area (58.27 m2/g) and large pore size (20.25 Å). The rates of hydrogen production for CaCO3, Ca0.9Co0.1CO3, Ca0.8Co0.2CO3 and Ca0.7Co0.3CO3 were 5204, 4381, 6666 and 6136 mL/g.min. The Ca0.8Co0.2CO3 catalyst revealed an activation energy for hydrogen catalytic reaction of 34.56 kJ/mol. The recyclability tests of Ca1-xCoxCO3 catalysts showed a reduction of efficiency by 7 % over 5 reaction cycles. Accordingly, the prepared Ca1-xCoxCO3 catalysts are promising for improved hydrogen production systems. This research contributes to advancements in hydrogen production technology.