Recently, the research group led by Xuan Weimin, a specially-appointed researcher at the College of Chemistry and Chemical Engineering, Donghua University, has made significant progress in the field of proton exchange membrane fuel cells. The related findings were published in Nature Chemistry under the title "Cation-directed assembly and sequential functionalization enable superprotonic polyanion–organic frameworks for high-power fuel cells."
The commercial application of proton exchange membrane fuel cells (PEMFCs) has long been constrained by the trade-off between proton conductivity and stability in membrane materials. To address this bottleneck, Xuan Weimin's research group proposed a supramolecular engineering strategy: using cationic building blocks with triangular symmetry to precisely anchor Keggin-type polyoxometalate (POM) anions through electrostatic interactions and C–H···O hydrogen bonds, successfully constructing a series of polyoxometalate–organic frameworks (POFs) with one-dimensional ordered channels. These materials exhibit excellent chemical stability and structural flexibility, and can be sequentially functionalized through post-modification to introduce protonated imidazole and alkylsulfonic acid groups, thereby demonstrating outstanding proton conduction performance. When the POFs were used as additives to modify composite proton exchange membranes, the fuel cell performance significantly surpassed that of commercial membranes, opening new avenues for the development of next-generation fuel cell separator membranes.
Figure 1 Schematic illustration of the synthesis and sequential functionalization of porous polyoxometalate–organic frameworks (POFs)
Figure 2 Proton conductivity of POFs and POF@Nafion composite membranes, and their fuel cell performance
Figure 3 Investigation of the proton conduction mechanism of SiW-POF2(0.3)-S(60%)
At 85 °C and 98% relative humidity, the sulfonated POF material SiW-POF2(0.3)-S(60%) achieved a proton conductivity of 7.04 × 10⁻² S·cm⁻¹, comparable to that of commercial Nafion membranes. Arrhenius analysis revealed a Grotthuss-type hopping mechanism for proton transport, with an activation energy as low as 0.39 eV. Upon incorporation of 3 wt% of this material into the Nafion matrix to form a hybrid membrane, the H₂-O₂ fuel cell tests delivered a maximum current density of 3400 mA·cm⁻² and a peak power density of 1367 mW·cm⁻², representing a 133% improvement over the pristine Nafion membrane. The composite membrane was continuously operated at 90–95 °C for 168 hours with a voltage degradation rate of only 0.23 mV·h⁻¹, demonstrating outstanding durability. Through solid-state nuclear magnetic resonance (NMR), variable-temperature infrared spectroscopy, and molecular dynamics simulations, the research team elucidated the microscopic mechanism underlying the efficient proton conduction: the sulfonic acid groups assembled a continuous hydrogen-bonding network comprising approximately 200 hydrogen bonds within a specific channel (Channel 1), providing an efficient pathway for proton hopping; in contrast, the hydrogen-bonding network in the other channel (Channel 2) remained discontinuous, supporting only localized transport. This work not only pushes beyond the performance limits of conventional proton exchange membranes but also establishes a new paradigm for the design of highly proton-conductive porous materials.
Qixin Zhao, a doctoral student at the College of Chemistry and Chemical Engineering, is the first author of the paper. Bo Li (Northeast Normal University / Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences), Dhruv Menon (University of Cambridge), and Chunmei Zhu (Donghua University) are co-first authors. Weimin Xuan, a specially-appointed researcher, is the corresponding author, with Professor Hongying Zang of Northeast Normal University and Professor David Fairen-Jimenez of the University of Cambridge serving as co-corresponding authors. Donghua University is the primary corresponding institution. This research was supported by the National Natural Science Foundation of China, among other projects. Technical support for crystal data collection was provided by the Testing Platform of the College of Materials Science and Engineering at Donghua University and the Shanghai Synchrotron Radiation Facility.
Original link to this article：https://www.nature.com/articles/s41557-026-02169-8
