Synergetic catalysis of Ni@C@CeO2 for driving ab/desorption of MgH2 at moderate temperature

Multiple catalysts have exhibited high activity on improving the hydrogen storage performance of MgH2. Herein, the hydrogen ab/desorption kinetics of MgH2 is significantly improved by using Ni@C@CeO2 as the catalyst. The results show that 10 wt%Ni@C@CeO2 doped MgH2 can absorb 4.51 wt% hydrogen within 60 min under low temperature 75 degrees C. Furthermore, the MgH2Ni@C@CeO2 composites release approximately 4.88 wt% H2 within 10 min at 325 degrees C. Moreover, the composites show excellent cycling performance, with negligible decrease in hydrogen storage capacity, hydrogen uptake rate and hydrogen release rate after ten cycles at 350 degrees C. The Rietveld refinement of X-ray diffraction and transmittance electron microscopy measurements reveal that Mg2NiH4/Mg2Ni and CeH2.73 phases are in-situ formed. The mutual conversion of Mg2Ni/Mg2NiH4 during hydrogen ab/desorption is a well-known hydrogen pump effect, which improvs the hydrogen storage performance of MgH2. The presence of CeH2.73 accelerate the conversion of Mg2Ni/Mg2NiH4, which we call 'facilitated hydrogen pump' effect. This attempt paves a potential way to achieve high performance Mg-based composites hydrogen storage materials via collaborative action between Ni and Ce species.

Automated summary

The hydrogen absorption/desorption kinetics of MgH2 can be significantly improved by using Ni@C@CeO2 as the catalyst. The composites, with 10 wt% Ni@C@CeO2 doped, can absorb 4.51 wt% hydrogen within 60 min at 75 degrees C and release approximately 4.88 wt% hydrogen within 10 min at 325 degrees C. In addition, the composites show excellent cycling performance with no decrease in hydrogen storage capacity, hydrogen uptake rate, and hydrogen release rate after ten cycles at 350 degrees C. The in-situ formation of Mg2NiH4/Mg2Ni and CeH2.73 phases enhances the hydrogen pump effect and accelerates the conversion of Mg2Ni/Mg2NiH4, which contributes to the improved hydrogen storage performance of MgH2.