Catalytic effect of carbon-supported NiCoFeCuMg high-entropy alloy nanocatalysts on hydrogen storage properties of MgH2

Abstract

High entropy alloy (HEA) based materials have been extensively investigated as viable catalysts in hydrogen storage for their unique properties. Herein, we demonstrate a relatively mild synthesis strategy for constructing carbon-supported by NiCoFeCuMg HEA (NiCoFeCuMg@C) nanocatalysts by utilizing polymetallic metal-organic frameworks (MOFs) as precursors. The incorporation of prepared catalysts into MgH₂ greatly improved the hydrogen storage performance: the MgH₂+NiCoFeCuMg@C composite can rapidly desorb 6.01 wt% H₂ at 325 °C, and the initial dehydrogenation temperature decreased to 167.2 °C, nearly 163.8 °C lower than that of the pure MgH₂. Besides, the composite exhibits a fairly stable reversible capacity with 97% capacity retention after 20 cycles. Most importantly, ex-situ structural characterization reveals that the synergistic effects of the “hydrogen pump” role of Mg₂Ni(Cu)/Mg₂Ni(Cu)H₄ and “hydrogen gateway” role of Co₃Fe₇, as well as the excellent dispersion function of carbon material, contribute to the outstanding hydrogen storage properties of the MgH₂+NiCoFeCuMg@C composite. This study provides valuable insights into the performance improvement of carbon-supported HEA catalysts in modification of MgH₂.