Improved hydrogen permeation through thin Pd/Al2O3 composite membranes with graphene oxide as intermediate layer

Here we proposed the decreasing in the roughness of asymmetric alumina (Al2O3) hollow fibers by the deposition of a thin graphene oxide (GO) layer. GO coated substrates were then used for palladium (Pd) depositions and the composite membranes were evaluated for hydrogen permeation and hydrogen/nitrogen selectivity. Dip coating of alumina substrates for 45, 75 and 120 s under vacuum reduced the surface mean roughness from 112.6 to 94.0, 87.1 and 62.9 nm, respectively. However, the thicker GO layer (deposited for 120 s) caused membrane peel off from the substrate after Pd deposition. A single Pd layer was properly deposited on the GO coated substrates for 45 s with superior hydrogen permeance of 24 x 10(-7) mol s(-1)m(-2) Pa-1- at 450 degrees C and infinite hydrogen/nitrogen selectivity. Activation energy for hydrogen permeation through the Al2O3/GO/Pd composite membrane was of 43 kJ mol(-1), evidencing predominance of surface rate-limiting mechanisms in hydrogen transport through the submicron-thick Pd membrane. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.