Novel Fe₃O₄@SiO₂/Co-Mo-B core-shell magnetic nanocatalyst: A reusable system for high-performance hydrogen evolution in borohydride hydrolysis

The present study focuses on the synthesis of a Fe₃O₄@SiO₂/Co-Mo-B core–shell nanocatalyst, designed as a high-performance and reusable system optimized for hydrogen evolution in borohydride hydrolysis reactions. The catalytic activity and hydrogen generation rate were evaluated by varying the catalyst amount, temperature, reusability, and MOH/MBH₄ wt% (M = Na, K). A range of characterization techniques, including FE-SEM, EDX, XRD, BET, XRF, TEM, XPS, and FTIR, were used to analyze the structure and composition of the samples. The Fe₃O₄@SiO₂/Co-Mo-B nanocatalyst demonstrated exceptional catalytic performance, achieving a hydrogen generation rate of 22.6 L g_metal⁻¹ min⁻¹ with an activation energy of 23.72 kJ mol^-1 for KBH₄ hydrolysis at 50 °C. For NaBH₄ hydrolysis, the HGR was 27.5 L g_metal⁻¹ min⁻¹, with an activation energy of 32.18 kJ mol⁻¹, demonstrating its high catalytic efficiency. Reusability studies over six successive cycles confirmed the stability of the catalyst, maintaining high hydrogen yields of 99.84 %–97.29 % for NaBH₄ and 95.25 %–99.09 % for KBH₄ across varying concentrations, further supporting its strong potential for industrial hydrogen storage and on-demand hydrogen generation. FE-SEM analysis revealed a grape-like morphology, while TEM confirmed a uniform Co-Mo-B coating (18–20 nm) on the SiO₂ shell, forming a robust core–shell structure that enhanced stability and durability. Additionally, the successful silica coating of Fe₃O₄ and effective adsorption of Co-Mo-B were validated, both of which contributed to the sustained catalytic activity of the catalyst. The remarkable performance of Fe₃O₄@SiO₂/Co-Mo-B in NaBH₄ and KBH₄ hydrolysis, combined with its low activation energy and high reusability, make it as a promising candidate for sustainable and scalable hydrogen generation.