Sustainable synthesis of Co/C nanocomposites from biomass for advanced MgH2-Based hydrogen storage: Insights into phase transformation and catalytic mechanisms

Developing sustainable catalysts for magnesium-based hydrogen storage systems is crucial for advancing clean energy technologies. Here, we report a facile synthesis strategy for Co/C nanocomposites using renewable sugarcane bagasse as a carbon precursor, achieving uniform dispersion of Co nanoparticles (<200 nm) within a hierarchically porous carbon matrix. The optimized MgH2+10 wt% Co/C composite exhibits dramatically enhanced hydrogen storage performance, with a reduction in dehydrogenation onset temperature from 330.4 degrees C to 209.4 degrees C and a 26 % decrease in apparent activation energy. The composite achieves rapid hydrogen uptake (6.2 wt% within 10 min at 150 degrees C) and excellent cycling stability (6.28 wt% after 10 cycles at 300 degrees C). Mechanistic studies reveal that the superior performance originates from the synergistic effects between the in-situ formed CoMg2/CoMg2H5 phases acting as "hydrogen pumps" and the porous carbon framework providing efficient pathways for mass/heat transfer. This work not only demonstrates an effective approach for developing high-performance hydrogen storage materials from renewable resources but also provides fundamental insights into the rational design of sustainable energy materials.