Investigating the effect of cobalt loading on thermal conductivity and hydrogen storage capacity of hollow glass microspheres (HGMs)

Abstract

In present study, cobalt loaded hollow glass microspheres (HGMs) were fabricated from amber colored glass powder blended with cobalt nitrate hexahydrate salt, by flame spheroidisation method. The morphology of the samples was observed using field emission-scanning electron microscope (FE-SEM), environmental SEM (ESEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy and X-ray diffraction (XRD) techniques. The results showed that HGMs with surface coating of cobalt oxide can be successfully synthesized using this single step process. Effect of cobalt loading percentage (0-10%) in the glass feed on the formation of cobalt loaded HGMs were studied. A continuous thin coating of cobalt oxide on the HGMs surface was obtained when the cobalt content in the feed glass powder was up to 2%. Further increase of the cobalt in the feed glass led to uneven coating on the surface of HGMs. A clear cut diffraction pattern for crystalline CoO was observed at the thick patches observed on the HGMs samples with 10% loading of cobalt. The thermal conductivity of HGMs increased when the cobalt loading increased from 0 to 10 wt.%. The hydrogen storage experiments done on all the prepared samples at 200 °C and 10-bar pressure showed that the hydrogen storage capacity increased when the Co percentage in the sample increased from 0 to 2%. The percentage of cobalt was increased beyond 2 wt.% showed a decline in the hydrogen storage capacity.