Spherical Carbon Derived from Sustainable Sources and Decorated with Silver Nanoparticles as a Catalyst for Hydrogen...

The reliance on carbon-based fuels remains a major contributor to greenhouse gas emissions, emphasizing the need for sustainable alternatives such as hydrogen. Sodium borohydride (NaBH₄), with a hydrogen content of 10.6 wt%, is a promising chemical hydrogen storage material capable of releasing four moles of H₂ per mole through hydrolysis; however, effective catalysts are essential for practical implementation. In this study, silver nanoparticles supported on glucose-derived carbon microspheres (AgSC) were synthesized and evaluated for catalytic NaBH₄ hydrolysis. Structural characterization (XRD, TEM, SEM, EDS) confirmed the uniform dispersion of metallic silver nanoparticles on the carbon support with no detectable Ag₂O phase. AgSC exhibited superior catalytic activity compared to unsupported Ag or bare carbon, achieving the highest hydrogen generation under neutral pH, elevated temperatures, and 835 µmol NaBH₄. The catalyst displayed an activation energy of 54 kJ mol^-1, turnover numbers (TONs) of 1.4 × 10⁵-1.9 × 10⁵, and turnover frequencies (TOFs) of 7.1 × 10⁴-9.3 × 10⁴ h^-1, demonstrating efficient utilization of active sites. pH-dependent studies revealed optimal hydrogen yield under neutral conditions, while acidic and basic media reduced performance due to surface poisoning and BH₄^- stabilization, respectively. Reusability tests showed only ~5% activity loss after five cycles. These findings establish AgSC as a stable, efficient, and recyclable catalyst for on-demand hydrogen generation, supporting sustainable clean fuel technologies.