Tailoring long-range ordered nanochannels in Nafion intercalated GO membrane for improved proton conduction

Abstract

Proton exchange membrane (PEM) is a key component for hydrogen production from water electrolysis, and the construction of PEM with continuous and controllable proton transport nanochannels is highly desirable. Albeit two-dimensional nanocomposite membrane features continuous transmission paths, maintaining high proton conductivity and membrane structure stability remain challenges. Here, we develop a structurally stable GO/Nafion composite membrane with long-range ordered proton transport channels. The assembled GO nanosheets provide continuous and straight interlaminar nanochannels, and the inserted Nafion ionomer with sulfonate groups is capable of regulating the physical and chemical microenvironments of the interlaminar channels for boosting the proton transfer via expanding the interlaminar spacing and affecting the hydrogen-bonding network. Additionally, glutaraldehyde serves as a cross-linking agent to bond the GO nanosheets for improving the stability of the membranes. The optimal GO/Nafion composite membrane exhibits a proton conductivity of 314 mS cm⁻¹ at 80 °C and 98% relative humidity. Meanwhile, it obtains a superior structure stability with a slightly decreased proton conductivity after immersion in water for 30 days. Moreover, the GO/Nafion membrane with GO as the main body and expensive Nafion as a modifier significantly decreases the production cost while maintaining a high proton conduction. This study which utilizes the synergistic manipulation of proton transfer channel and its microenvironments provides an effective strategy for fabricating high-performance and low-cost proton exchange membranes.