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 sp²carbon 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.