Hydrogen sorption and desorption behaviors of metal-carbon composites prepared by alcohol CVD method

In order to provide with novel composites with high specific surface area for hydrogen storage, FeNiCr-carbon composites were prepared by an alcohol chemical vapor deposition (ACCVD) method with methanol as a carbon source, wherein the abbreviation FeNiCr denoted powdery mixture of hydrogenated Fe, Ni and Cr. After the ACCVD synthesis, the composites were optionally ground to expose inner sorption sites. The peak temperature of hydrogen desorption from as-prepared FeNiCr-carbon composite hydrogenated at 653 K under 1.1 MPa of hydrogen was 723 K, as recorded by temperature programmed desorption (TPD). The peak temperature of hydrogen desorption from ground FeNiCr-carbon composite hydrogenated under the same conditions was as low as 423 K. HD molecules were detected by TPD, after the ground FeNiCr-carbon composite was similarly hydrogenated at 653 K under mixed H2 plus D2 gas. Such was also the case, after the ground composite was hydrogenated at room temperature. It was evidenced that atomic hydrogen took part in hydrogen sorption by the ground composite. The maximum hydrogen concentrations of the FeNiCr-carbon composites were 0.59 mass% and 1.16 mass%, before and after grinding, respectively, at 77 K under 0.77 MPa of hydrogen.