Light metal hydrolysis for hydrogen supply is well suited for portable hydrogen fuel cells. The addition of catalysts can substantially aid Mg hydrolysis. However, there is a lack of clear catalytic mechanism to guide the design of efficient catalysts. In this work, the essential role of nanosized catalyst (Ni3 Fe/rGO) in activating micro-sized Mg with ultra-rapid hydrolysis process is investigated for the first time. Here, an unprecedented content of 0.2 wt% Ni3 Fe/rGO added Mg can release 812.4 mL g-1 hydrogen in just 60 s at 30 °C. Notably, an impressive performance with a hydrogen yield of 826.4 mL g-1 at 0 °C in only 30 s is achieved by the Mg-2 wt% Ni3 Fe/rGO, extending the temperature range for practical applications of hydrolysis. Moreover, the four catalysts (Ni3 Fe/rGO, Ni3 Fe, Ni/rGO, Fe/rGO) are designed to reveal the influence of composition, particle size, and dispersion on catalytic behavior. Theoretical studies corroborate that the addition of Ni3 Fe/rGO accelerates the electron transfer and coupling processes and further provides a lower energy barrier diffusion path for hydrogen. Thus, a mechanism concerning the catalyst as migration relay is proposed. This work offers guidelines designing high-performance catalysts especially for activating the hydrolysis of micro-sized light weight metals.
Keywords: Mg hydrolysis; catalyst; hydrogen generation; migration relay.
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