Self-Standing and Flexible Silk Fibroin-Modified Graphene Oxide Membrane for Selective Hydrogen Permeation

Graphene oxide (GO) membranes have attracted considerable interest due to their oxygenated functional groups and their potential in hydrogen (H2) separation applications. This work introduces a flexible and stable lamellar graphene oxide membrane combined with silk fibroin (SF) for hydrogen permeation performance. The intercalating of silk fibroin into GO nanosheet enhanced the interlayer distance of a membrane by 43%, promoting the uptake of a significant amount of water molecules that develop hydrogen bonds between SF and GO. GO-SF has an improved proton conductivity of 1.2 mS cm–1, similar to that of Nafion, and conserves stability up to 100 °C. Concentration cell experiments demonstrated that the SF-modified membrane displays as a pure proton conductor at ambient temperature and up to 60 °C. In addition, the diffusion of electrons occurs between the sp2 carbon backbone of the GO layer and the hydrophobic site of SF, enabling the mixed proton and electron conductivity. The GO-SF membrane, covered with Pt/C on both the anode and cathode, efficiently allows for the permeation of hydrogen gas while preventing the migration of He and CO2. Our research findings demonstrate the significant potential of carbon-based membranes for hydrogen separation applications.