Synthesis of Co3O4 macrocubes catalyst using novel chitosan/urea template for hydrogen generation from sodium borohydride

Abstract

Co3O4 catalyst with porous macrocubes structure were one pot formulated by hydrothermal treatment of chitosan/urea/Co(NO3)2·6H2O mixtures at 180 °C for 8 h and then calcined at different temperatures for 4 h. Chitosan and urea are both compounds containing amino group, which made them different from the previous supporting materials. In this study, chitosan was the major template in the solution and determined the shape of the Co3O4 catalyst while urea played a major support to cobalt (II) nitrate hexahydrate during crystal growth of the catalyst. The prepared materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), UV–vis Absorption Spectrum and BET technique. A remarkably high hydrogen generation rate of 1497.55 mlH2 min−1 gcat−1 was obtained from the hydrolysis of 2 wt % NaBH4 solution with 0.02 g catalyst at 25 °C. The catalytic activity of the as-prepared sample was examined for hydrolysis reaction of sodium borohydride (NaBH4) at different temperatures, catalyst amount and NaBH4 concentration. The results reveal that the average crystallite size, macrocubes thickness, surface properties and catalytic activity of Co3O4 macrocubes could be controlled by varying the mass ratio of chitosan/urea to cobalt concentration.