• Al substitution promotes C14 phase formation whereas Fe promotes C15 phase, significantly altering hydrogen storage capacity and plateau pressure.
• The Fe0.1 alloy achieved the largest adsorption capacity and highest plateau pressure, while the Al0.1 alloy exhibited opposite characteristics.
• All alloys demonstrated rapid hydrogen adsorption kinetics (98% capacity within 1 min) and stable cycling performance over 20 cycles.
• Fe doping enhances discharge capacity and high-rate discharge performance via improved electrocatalytic activity and hydrogen diffusion.