With the acceleration of advanced industrialization and urbanization, the environment is deteriorating rapidly, and non-renewable energy resources are depleted. The gradual advent of potential clean energy storage technologies is particularly urgent. Electrochemical energy storage technologies have been widely used in multiple fields, especially supercapacitors and rechargeable batteries, as vital elements of storing renewable energy. In recent years, two-dimensional material MXene has shown great potential in energy and multiple application fields thanks to its excellent electrical properties, large specific surface area, and tunability. Based on the layered materials of MXene, researchers have successfully achieved the dual functions of energy storage and conversion by adjusting the surface terminals at the Fermi level. It is worth noting that compared with other two-dimensional materials, MXene has more active sites on the basal plane, showing excellent catalytic performance. In contrast, other two-dimensional materials have catalytic activity only at the edge sites. This article comprehensively overviews the synthesis process, structural characteristics, modification methods for MXene-based polymer materials, and their applications in electrochemical energy storage. It also briefly discusses the potential of MXene-polymer materials in electromagnetic shielding technology and sensors and looks forward to future research directions.

Polymeric perylene diimide (PDI) has been evidenced as a good candidate for photocatalytic water oxidation, yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration. Herein, with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern, the electronic structure is theoretically illustrated by the first-principles density functional theory calculations, suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI. It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis. The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H₂O → *OH → *O → *OOH → *O₂ with an overpotential of 0.81 V. Through an in-depth theoretical computational analysis in the atomic and electronic structures, the origin of photocatalytic oxygen evolution activity for PDI is well illustrated, which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.

The sodium-iodine (Na-I) battery exhibits significant potential as an alternative energy storage device to the lithium-ion battery. However, its development is hindered by inadequate electrical and thermal stability, as well as the dissolution and shuttling of polyiodide. In this study, we report a preparation method for melamine carbon sponge (MC) via carbonizing a commercially available kitchen sponge. It was revealed that the as-prepared MC, composed of unique self-growing carbon nanotubes, could provide both physical and chemical adsorption capabilities for intermediate polyiodides to improve the electrochemical performance of NaI. Consequently, the NaI/MC electrode effectively minimized polyiodide dissolution and reduced the electrochemical impedance. The NaI/MC cathode demonstrated a high average discharge capacity of 92.75 mAh·g^-1 over 200 cycles while maintaining a coulombic efficiency of 94%. The research findings from our study have promising applications in Na-I batteries.

Mesoporous carbon supports mitigate Pt sulfonic poisoning through nanopore-confined Pt deposition, yet their morphological impacts on oxygen transport remain unclear. This study integrates carbon support morphology simulation with an enhanced agglomerate model to establish a mathematical framework elucidating pore evolution, Pt utilization, and oxygen transport in catalyst layers. Results demonstrate dominant local mass transport resistance governed by three factors: (1) active site density dictating oxygen flux; (2) ionomer film thickness defining shortest transport path; (3) ionomer-to-Pt surface area ratio modulating practical pathway length. At low ionomer-to-carbon (I/C) ratios, limited active sites elevate resistance (Factor 1 dominant). Higher I/C ratios improve the ionomer coverage but eventually thicken ionomer films, degrading transport (Factors 2-3 dominant). The results indicate that larger carbon particles result in a net increase in local transport resistance by reducing external surface area and increasing ionomer thickness. As the proportion of Pt situated in nanopores or the Pt mass fraction increases, elevated Pt density inside the nanopores exacerbates pore blockage. This leads to the increased transport resistance by reducing active sites and increasing ionomer thickness and surface area. Lower Pt loading linearly intensifies oxygen flux resistance. The model underscores the necessity to optimize support morphology, Pt distribution, and ionomer content to prevent pore blockage while balancing catalytic activity and transport efficiency. These insights provide a systematic approach for designing high-performance mesoporous carbon catalysts.