Polymeric carbon nitride supported single-phase Ni with exceptional catalytic effect on MgH2 for hydrogen storage

Magnesium hydride (MgH 2 ) with its high hydrogen storage capacity (7.6 wt%) and exceptional reversibility, has emerged as a promising solid-state hydrogen storage material. This study designed a polymeric carbon nitride (PCN) supported single-phase Ni catalyst with superior thermal stability and catalytic activity. The optimized PCN-Ni catalyst significantly reduced the initial dehydrogenation temperature of MgH 2 to 192 ºC. At 295 ºC, the composite released 6.10 wt% H 2 within 5 min, and it subsequently absorbed 5.50 wt% H 2 within 5 min at 150 ºC. Compared to pristine MgH 2 , the activation energies for dehydrogenation and hydrogen absorption were reduced by 31.6 % and 29.4 %, respectively. Moreover, the MgH 2 + 10 wt% PCN-Ni composite exhibited remarkable cycling stability, with capacity retention rates of 96.0 % and 96.7 % after 20 hydrogenation/dehydrogenation cycles. In conclusion, this work provides a new perspective on the heterogeneous synergy of transition metal and carbon nitride composite catalysts in promoting the dehydrogenation/rehydrogenation reactions of MgH 2 and lays the foundation for the design and fabrication of highly efficient catalysts in other energy storage related fields.