Preparation of Co3−xCaxO4 nanostructure catalyst for improved hydrogen production from sodium borohydride

Hydrogen energy is becoming increasingly important because it is a clean and renewable source of energy. The present work reports the preparation of calcium doped Co3O4 as a catalyst for hydrogen production from sodium borohydride. Techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR spectroscopy were used to characterize Co3−xCaxO4 nanostructures. XRD peaks have been indexed to the standard cubic structure of Co3O4. The estimated average crystal size ranged from 14 to 16 nm. The vibrational modes of calcium doped Co3O4 were detected in the FTIR spectra. The data analysis of XPS spectroscopy is used to explore the chemical composition of the Co3-xCaxO4 surface. SEM micrographs showed mesoporous Co3O4 with a porous structure that is made up of cobalt oxide nanoparticles. The specific surface areas of Co3O4, Co2.9Ca0.1O4, Co2.8Ca0.2O4, and Co2.7Ca0.3O4 are 192, 57, 63, and 70 m2/g, respectively. The addition of calcium reduced the optical energy gap of Co3O4 from 1.95 to 1.85 eV. All the prepared catalysts showed a photoluminescence (PL) emission peak around 427 nm. The Co3O4, Co2.9Ca0.1O4, Co2.8Ca0.2O4, and Co2.7Ca0.3O4 catalysts showed high catalytic activity, with Co2.8Ca0.2O4 showing the highest rate of hydrogen production (3025 mL/g.min).