Hydrogen generation from NaBH4 hydrolysis using biomass-derived seed shell supported Co-La-B catalysts: A comparative study of sunflower, pumpkin and watermelon shell supports

The development of cost-effective and sustainable catalysts is essential for efficient hydrogen production. In this study, biomass-derived biochars obtained from sunflower, watermelon, and pumpkin seed shells were employed as supports for Co-La-B nanocatalysts used in sodium borohydride (NaBH4) hydrolysis. The biochars were prepared via hydrothermal carbonization at 180 degrees C and subsequently used as porous carbon matrices for metal deposition. Structural characterization (SEM-EDX, FT-IR, BET, and XRD) confirmed the successful dispersion of Co-La-B nanoparticles on the biomass-derived supports. Among the prepared catalysts, the sunflower seed shellsupported Co-La-B catalyst exhibited the highest catalytic activity, achieving a hydrogen generation rate of 11.086 mL min(-1) g(cat)(-1) at 40 degrees C, which is approximately three times higher than that of the unsupported catalyst. Reaction parameters including metal loading, NaOH concentration, NaBH4 concentration, catalyst amount, and temperature were systematically investigated to determine optimal conditions. Kinetic analysis revealed an activation energy of 38.48 kJ mol(-1) and a reaction order of 0.9, indicating nearly first-order behavior. The enhanced catalytic performance is attributed to the synergistic interaction between Co, La, and B species and the porous biochar support, which improves metal dispersion and active site accessibility. These results demonstrate that biomass-derived supports provide an environmentally friendly and efficient platform for hydrogen generation via NaBH4 hydrolysis.