Wenmu Li

Economical Fe-N-C catalysts are considered as promising alternatives to platinum group metal catalysts for proton exchange membrane fuel cells (PEMFCs). Despite exhibiting robust activity on rotating disk electrodes, their performance within membrane electrode assemblies often experiences limitations, such as decreased O2 diffusion, high H2O2 formation, low proton conduction, and a lower electron transfer number. In this study, key factors, including proton transport, electron conduction, and gas diffusion within air-breathing PEMFCs, have been investigated by adjusting cathode catalyst layer (CCL) compositions. From the experimental results, the optimal peak power density was obtained when the loading of Fe-N-C catalyst was 1 mg∙cm–² and Nafion content was 0.15 mg∙cm–² within CCLs. The addition of polytetrafluoroethylene to enhance hydrophobicity was found to have a negative impact on PEMFC performance. Furthermore, the incorporation of diverse carbon nanotubes into CCLs resulted in a significant increase of over 30% in peak power density, attributed to enhancements in the gas diffusion and proton conductivity. The critical roles of gas transport and proton conductivity within Fe-N-C-based CCLs have been highlighted by this study. These findings contribute to the advancement of rational design principles for economical PEMFCs, offering valuable insights to drive the development of efficient and cost-effective technology in future.

To address the challenges of multifunctional integration in electronic devices, this study establishes a versatile material matrix that combines exceptional performance with structural design flexibility, enabling multifunctional “on-demand integration” and “synergistic optimization.” We successfully constructed a polyimide Janus matrix film through an innovative dual-pore-forming agent synergistic pore-forming strategy. The unique “dense-layer-porous-layer” asymmetric structure integrates high mechanical strength (>70 MPa), flexibility, ultralow thermal conductivity (0.067 W·m^–1·K^–1), and outstanding chemical stability, forming a tailorable functional integration universal platform We demonstrated its “on-demand functionalization” potential by loading CNTs@Fe₃O₄ hybrid materials, transforming the platform into a functional composite with advanced capabilities such as highly efficient electromagnetic shielding (>40 dB) and active overheating warning. This work transcends the traditional approach of developing single-function materials. The constructed polyimide platform material provides an innovative solution for the integrated design of future electronic devices.

The utilization of harsh chemicals is obligatory during the preparation of biomass-derived carbon materials. ZIF-8 serves as a zinc-based metal–organic framework (MOF), in which the internal zinc ions (Zn²⁺) are reduced to metallic Zn during high-temperature pyrolysis, which then evaporates and etches the carbon skeleton, significantly increasing the specific surface area and porosity of the material. In the current work, the ZIF-8 and the legume root nodules were used as an activator and biomass precursors to develop a more atom-economical and eco-friendly strategy for the preparation of porous carbon materials. The roles the ZIF-8 and the species of legume root nodules play in the structure and performance of the final carbon materials were well explored and discussed. The specific surface area of our optimal carbon RW@Z8(5) is up to 1459.27 m² g⁻¹. The catalyst RW@Z8(5) was employed in fuel cells for the oxygen reduction reaction (ORR) and demonstrated a half-wave potential (E_1/2) of 0.720 V (vs. RHE) in 0.1 M HClO₄, which is only 88 mV lower than that of the Pt/C catalyst. Our results prove the possibility of the metal–organic framework (MOF) activation strategy for the development of biomass-derived porous carbon materials.

There is growing interested in high refractive index polymers due to their numerous applications in optical materials. In current work, we reported a facile strategy to improve the refractive index of the optical materials. The new asymmetric binary thiol dopants containing high molar refractive index heteroatoms (S and P) and large conjugated groups were successfully designed and synthesized. Using these additives, the high refractive index silicone polymers were developed from these dopants and vinyl silicones simply via the light-cured reaction. The effects of dopants’ structure and content on the thermal and optical properties of cured silicone polymers were systematically investigated. The results show that the asymmetry structure of the dopants can not only effectively offset the accumulated trend of the large conjugated groups but also improve the refractive index of cured silicone polymers. Even with 5% dopant’s loading, the refractive index of the SOV-5 increased from 1.5773 to 1.5803 without notably sacrificing its the light transmittance. The glass transition temperature of the cured silicone polymers decreases, even though their crosslink density increase with the growing of the dopants’ loading.

Controllable coordination and efficient sensitization of rare earth ions in polymer materials are key to achieving high‐performance optoelectronic polymers. By designing aromatic diamines, polyimides are synthesized with 1,10‐phenanthroline benzimidazole groups (PBG) in the polymer backbone. Utilizing the coordination between PBG and rare earth ions (Eu³⁺, Tb³⁺), polyimide‐rare earth complexes are formed and precisely characterized their structures. The unique coordination allows PBG to effectively sensitize Eu³⁺, resulting in efficient, long‐lived red emission. Furthermore, PBG maintains excellent coordination with Eu³⁺ in acidic environments, granting acid‐responsive color changes for data encryption. Importantly, PBG sensitization of Tb³⁺ enabled full‐spectrum emission (CIE coordinates: (0.31, 0.35)) within a single rare earth‐polyimide complex, due to electron transfer among the ions, ligands, and polymer. This leads to the design of a multi‐layer PLED device with an optimal external quantum efficiency of 0.43% for white light emission (CIE coordinates: (0.28, 0.34)). Through comparative theoretical and experimental analysis, the photophysical behavior of these coordinated polyimides is explained and explored their photoluminescent and electroluminescent properties. This research integrates the advantages of rare earth elements and polyimides, creating novel luminescent polymers with diverse optical applications, providing a new strategy for designing luminescent coordination polymers.