Novel Fe3O4@SiO2/Co-mo-b Core-Shell Magnetic Nanocatalyst: a Reusable System for High-Performance Hydrogen Evolution in Borohydride Hydrolysis

Abstract

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 gmetal -1 min-1 with an activation energy of 23.72 kJ mol-1 for KBH4 hydrolysis at 50 degrees C. For NaBH4 hydrolysis, the HGR was 27.5 L gmetal -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 CoMo-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.