Amorphous Co–Cu catalysts confined in PVHF nanofibers for sustainable hydrogen generation from ammonia borane methanolysis

A series of amorphous Co–Cu nanoparticles (NPs) confined within electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP, PVHF) nanofiber (NF) membranes was synthesized and evaluated for catalytic H 2 generation via ammonia borane (AB) methanolysis under mild conditions. Catalysts with varying Co:Cu ratios were fabricated through electrospinning followed by in situ chemical reduction. Among them, the 60 Co@PVHF nanofibrous membrane exhibited the highest performance, achieving nearly complete AB dehydrogenation (3.0 mol H 2 per mol AB) within 10 min at 25 °C. This result corresponded to an H 2 evolution rate of approximately 0.322 mol H 2 min −1 . Structural characterizations (FESEM, EDX, TEM, and XRD) confirmed homogeneous metal dispersion and an amorphous phase conducive to active site exposure and efficient electron transport. Kinetic analysis indicated a first-order dependence on catalyst dosage and a zero-order dependence on AB concentration, suggesting a surface-mediated mechanism. The activation energy ( E a ), determined to be 15.61 ± 1.2 kJ mol −1 , was significantly lower than those of many reported Co- and Ni-based catalysts. Thermodynamic parameters (ΔH‡ = 12.78 ± 1.3 kJ mol −1 , ΔS‡ = +13.02 ± 1.2 J mol −1 K −1 ) revealed a spontaneous and endothermic reaction pathway, while the Gibbs free energy of activation (ΔG‡ < 0) confirmed the feasibility of H 2 evolution. The 60 Co@PVHF catalyst retained over 90 % of its initial activity after five consecutive cycles, demonstrating excellent reusability and structural integrity. These findings highlight the Co–Cu@PVHF nanofibrous membrane as a promising, flexible, and recyclable catalyst platform for efficient H 2 production from AB methanolysis.