A composite DIOX/PSNS-g-CTAB promotion system enhances hydrate-based solidified hydrogen storage

Hydrogen is crucial for advancing human society towards a zero-carbon future, but its storage remains a core challenge for practical application. While hydrate-based solidified hydrogen offers a promising strategy for mild hydrogen storage, the poor hydration efficiency of hydrogen-containing hydrates hinders commercialization. To address this, a novel nanopromoter of PSNS-g-CTAB (CTAB grafted on polystyrene nanospheres) was prepared, and a composite promotion system of DIOX/PSNS-g-CTAB was proposed to enhance hydrate growth kinetics, and its performance on improving the three key metrics of hydration efficiency was evaluated. Remarkably, the addition of a small amount of PSNS-g-CTAB (1 mmol/L) significantly enhance hydration efficiency: hydrate induction time decreased from 443.2 ± 280 min to 47.6 ± 46.3 min, hydrogen storage capacity and hydrate growth rate increased up to 0.447 ± 0.111 wt% and 0.057 mmol/min/mL, with an improvement of 54.1% and 35.7% separately, and the fast hydrate growth reduced T90 by 73.5%. The competitiveness of this promotion system was assessed, revealing unique advantages over previously reported promoters. Hydrate microstructure and crystallization were investigated via Raman spectroscopy and in-situ differential scanning calorimetry (μ-DSC), respectively. Results indicate hydrate cages' multiple occupy and composite hydrate structures, suggesting PSNS-g-CTAB's promotion on interfacial crystallization, and a hydrate formation pattern of interfacial “re-orientation–encapsulation–granulation–accumulation' was proposed.