Influence of Pd nanoparticles on the structural stability and hydrogen separation of graphene oxide membranes

Thin graphene oxide (GO) membranes decorated with palladium (Pd) nanoparticles (NPs) were fabricated and evaluated for high-temperature H₂/N₂ separation. Pd NPs were synthesized by chemical reduction using ascorbic acid and incorporated into GO nanosheets. Laminate thin film composite (TFC) membranes were prepared by vacuum filtration of a solution of GO and Pd NPs at varying loadings (0.1–5 wt%) onto polyethersulfone (PES) supports. A neat GO membrane (225 nm) exhibited an H₂ permeance of 500 GPU and an H₂/N₂ selectivity of ~31 at 220 °C, attributed to thermal reduction of GO that enhances molecular sieving. Incorporation of 0.1 wt% Pd raised permeance to 650 GPU with a moderate drop in selectivity to 28, while 0.5 wt% Pd enhanced permeance to 1400 GPU with a selectivity of 17.5. Higher Pd loadings (5 wt%) further increased permeance to 16,000 GPU but caused selectivity to drop below 5, due to nanoparticle agglomeration and the formation of nonselective voids. These results demonstrate that low Pd loadings can enhance hydrogen flux with a moderate selectivity loss, but excessive Pd disrupts GO layering. Pd NPs, which exhibit lower hydrogen embrittlement susceptibility than bulk Pd, offer a promising route to high-temperature H₂ separation with optimized Pd content.