Anisotropic porous polymer-based nickel composites as catalytic membrane contactors for directional hydrogen gas release from ammonia borane solution

Liquid chemical hydrogen carriers offer an attractive route for storage and transport, but their practical use requires controllable on-demand H 2 gas release systems. Although catalysts show high activity, practical reactor concepts remain limited. Here, we explore a catalytic liquid / gas membrane contactor concept where the membrane acts as both catalyst support and transport-controlling element. Utilizing one-step casting solution preparation followed by non-solvent induced phase separation, we fabricated porous anisotropic polymer-nickel membranes and variants containing the cationic ionomer Fumion or carbon black to tailor microenvironment, wetting, and pore morphology. Membranes were characterized by SEM/EDX, metal content (via AAS), and water contact angle measurements, and evaluated via gas/liquid transport experiments and catalytic H 2 gas release tests in multiple experimental configurations targeting distinct transport aspects, including cross-flow contactor experiments to probe membrane property and -orientation effects on the performance. Additives significantly improved nickel incorporation (from 55% to 88-98%) and increased water contact angles (from 64° to 81-93°, for bottom surface), while modifying the asymmetric pore morphology. The carbon black variant exhibited the most favorable three-phase behavior, indicating that hydrophobicity and morphology jointly promote liquid distribution and gas bubble release. In batch H 2 gas release tests, the hydrophilic reference suffered transport limitations with rates dropping to ≈0.04 mL(H 2 )∙min -1 ∙mg(Ni) -1 . In contrast, additive-modified membranes maintained ≈0.13 mL(H 2 )∙min -1 ∙mg(Ni) -1 , with the carbon black variant sustaining performance over multiple cycles. Cross-flow experiments confirmed orientation-dependent H 2 gas release through the asymmetric pores. While the carbon black variant outperformed others with a 3-4x higher rate, observed liquid breakthrough indicates that measures to suppress such breakthrough are critical for robust operation.