Proton exchange membrane fuel cell (PEMFC) has attracted great attention as an energy conversion technology, especially in the fields of new energy vehicles. The core component of PEMFC is membrane electrode assembly (MEA), which is consist of proton exchange membrane (PEM), gas diffusion layer (GDL) and catalyst layer (CL). Notably, the catalyst layer serves as the center for electrochemical reactions that generate electricity. Besides the state-of-the-art materials, the catalyst ink properties and CL structure also have a great effect on performance, durability, and cost of PEMFC. However, it is not very clear how the interactions between different components of catalyst ink, the CL formation procedure as well as inhomogeneous CL structure affect the overall performance. This review, therefore, mainly focuses on recent advancements in catalyst ink dispersion methods, complex interactions between the ink materials and new processes to improve the stability of catalyst ink. In addition, this review will highlight advanced CL structure designs, their impact on the fuel cell performance, and introducing advanced techniques for a deeper analysis of the CL structure. Finally, this review emphasizes the challenges and perspectives in catalyst ink and CL studies, which are crucial for the regulation and development of high-performing PEMFCs.

Molecular-based ferroelectrics have received extensive attention from materials scientists in recent years due to their light weight, high flexibility, and environmental friendliness. However, the precise design of molecular-based ferroelectrics by using crown ether supramolecular systems remains a huge challenge. In this work, L-valine (L-Val) and 18-crown-6 were selected as the guest and host molecules, respectively, for constructing crown ether complexes: [L-Val]₂⁺(18-crown-6)₃(H₂O)₂[FeX₄]₂^- (X = Cl (1), Br (2)) by halogen modulation. The results indicated that compound 1 exhibits a reversible phase transition accompanied by symmetry evolution from P1 to I2/m at room temperature. The implementation of halogen substitution strategy resulted in compound 2 crystallizes in C2/m space group, and the phase transition temperature was changed by 30 K. Meanwhile, oscillations of supramolecular groups within the framework conferred significant coupled physical properties, including reversible dielectric anomalies, reversible magnetic transfers, spin crossovers (SCOs), the band gap value decreases, paraelectric–ferroelectric phase transitions, and a second-harmonic generation (SHG) response. In short, this work provides a brand new perspective on expanding the multifunctionality of crown ether supramolecular systems.

Rare-earth-doped fluorescent hydrogels, while effective for optical sensing, often have limited functionality due to weak physical crosslinking. Stretchable chemically crosslinked conductive hydrogel sensors, essential for adhering to the human body to monitor movements, typically hinder fluorescence. This is caused by the opacity of conductive components, and adhesion molecules like catechol may quench fluorescence. These constraints limit the multifunctional applications of hydrogels that combine both physical and chemical crosslinking. In this study, we blend and polymerize acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and iminodiacetic acid (IDA)-modified carboxymethyl cellulose sodium (CMC—Na) to form hydrogels, while introducing rare-earth elements to achieve synergistic benefits. This novel approach yields hydrogels with low hysteresis, high strain (1150%), ultra-fast response capability (50 ms), and high sensitivity (GF = 5.03), facilitated by the physical crosslinking of rare-earth ions. By adjusting the IDA content or the Eu³⁺/Tb³⁺ ratio, we can precisely control the hydrogel’s brightness, achieving tunable red/yellow/green fluorescence variations through radiative transitions. Additionally, we have developed, for the first time, a fluorescence/conductivity dual-channel sensor that responds to pressure changes by displaying color shifts. This represents a new strategy for multifunctional rare-earth-doped hydrogels and flexible sensing applications.

The most notable structural features of polyoxometalates (POMs) are their large molecular size and relatively low effective surface charge density. These properties endow POMs with excellent Brønsted acidity and proton mobility, making them ideal materials for proton conductors. In this study, a series of homotrimeric complexes were successfully synthesized through Ln³⁺/Bi³⁺ induced assembly of a suitable organic ligand 1-hydroxyethylidene 1,1-diphosphonic acid (HEDP): H₉[La(Mo₂O₄)₆(H₂O)₆(HEDP)₆](LaO₉H₆)·18H₂O (complex 1), H₉[Nd(Mo₂O₄)₆(H₂O)₆(HEDP)₆](NdO₆H₁₂)·15H₂O (complex 2), and H₉[Bi(Mo₂O₄)₆(H₂O)₆(HEDP)₆] (complex 3). Notably, the presence of free rare earth ions in the asymmetric unit of complexes 1 and 2 is a structural feature that results in a tighter hydrogen-bonding network in their three-dimensional stacking structures, which in turn significantly enhances the proton conductivity. Complexes 1–3 exhibit excellent proton conductivity, with measured values of 3.35 × 10^–2, 3.81 × 10^–2, and 2.37 × 10^–2 S/cm under 98% relative humidity at 80 ℃. This study establishes a promising strategy for designing molybdate cluster-based materials with enhanced proton conduction properties.

Low-temperature energy storage technology plays a crucial role in sustaining energy supply for interstellar exploration, polar research stations, military facilities in extremely cold regions. Sodium-ion batteries (SIBs) are regarded as potential candidates for large-scale energy storage systems under extreme low-temperature conditions due to their abundant sodium resources, low cost and superior temperature tolerance. As a critical component of SIBs, the electrolyte is closely related to the charge transfer kinetics within the battery and significantly influences its low-temperature electrochemical performance. Herein, we present a comprehensive review focusing on recent advances in organic liquid electrolytes for enhancing the low-temperature performance of SIBs. Firstly, the failure mechanisms of SIBs at low temperatures are systematically analyzed from the perspective of charge transfer kinetics. Subsequently, the electrolyte design strategies for low-temperature SIBs are introduced based on two evaluation dimensions: half cell and full cell systems. Finally, the future research directions for developing advanced electrolytes to improve the low-temperature performance of SIBs are proposed. This review provides valuable insights into electrolyte optimization strategies, which are expected to accelerate the development of high-performance SIBs for reliable energy storage in extreme cold environments.

The conjugation of metal-organic architectures with metal nanoparticles into a multicomponent system is an attractive route for designing myriad materials with structural complexity, integrated properties, and important applications. Herein, we report a single-crystal to single-crystal transition from the thiacalixarene-based octahedral coordination cage Co₂₄-Na to Co₂₄-Ag and the construction of nanohybrids (Co₂₄-Ag@Ag-NPs) by combining Co₂₄-Ag with silver nanoparticles (Ag NPs) for photothermal conversion. The multicomponent Co₂₄-Ag@Ag-NPs not only combined and enhanced the light absorption effect of Co₂₄-Ag and the plasmon effect of Ag NPs but also offered the Mott-Schottky heterojunction. Benefiting from the improved photo-response ability and the protective effect of calixarene in preventing heat loss, Co₂₄-Ag@Ag-NPs exhibited significant visible light photothermal conversion performance.

Cyclic trinuclear complexes (CTCs) are coordination compounds composed of three metal atoms arranged in a cyclic structure, which imparts them with significant potential for catalytic applications. However, their practical use is often hindered by issues of low chemical stability and poor dispersity. In this work, we present an efficient strategy for stabilizing trinuclear copper complexes [tris(µ₂–4-carboxaldehyde-pyrazolato-N,N’)-tri-copper(Ⅰ) monohydrate, Cu₃(PyCA)₃·H₂O] by chemically incorporating them into the core of diblock copolymer aggregates. Specifically, we utilize reversible addition-fragmentation chain transfer (RAFT) polymerization to synthesize poly(2-aminoethyl methacrylate hydrochloride)₅₀-block-poly(glycerol monomethacrylate)₅₂ (A₅₀-G₅₂) diblock copolymers. The subsequent reaction between primary amine groups of the A₅₀ block and aldehyde groups of the Cu₃(PyCA)₃·H₂O leads to the formation of A₅₀-G₅₂-Cu₃(PyCA)₃ hybrid nanoparticles, in which the G₅₂ blocks serve as steric coronas, while the Cu₃(PyCA)₃·H₂O are incorporated within the core domain. Notably, these hybrid nanoparticles exhibit enhanced stability and improved catalytic performance in the Sonogashira cross-coupling reaction in air. Through the precise design of reactive block copolymers, this study presents a novel strategy for the particleization of CTCs, thereby enabling the practical and scalable preparation of a diverse range of CTCs-based functional materials with enhanced properties.

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based solid polymer electrolytes show great potential for high energy lithium metal batteries, however, the residual solvent and related severe side reactions limit its development. Herein, a PVDF-HFP-based solid polymer electrolyte modified by fluorobenzene (FB) co-solvent is designed to address these problems. The introduced FB with weak solvation interaction regulates the coordination environment and induces anions to enter the solvation structure, generating more contact ion pairs (CIPs) and aggregates (AGGs). In addition, the anions-derived LiF-rich interphases help to improve the interface stability against Li metal. As a result, the FB-PVDF-HFP achieves high ionic conductivity (4.1 × 10⁻⁴ S/cm) and low activation energy (0.125 eV) at room temperature. In addition, Li||Li symmetric cells using FB-PVDF-HFP electrolyte can achieve uniform and dendrite-free lithium deposition/stripping in the long-term cycling over 2300 h. The assembled solid-state Li|FB-PVDF-HFP|LFP full cell shows improved rate performance and cycling performance (600 cycles at 0.5 C and 450 cycles at 3 C) at room temperature. This work verifies the feasibility of fluorinated terminated solid polymer electrolytes on its lithium-ion transport and interfacial stability in lithium metal batteries.

Solid-state electrolytes composed of earth-abundant elements offer significant cost advantages for large-scale energy storage applications. However, their widespread adoption is hindered by inherently low ionic conductivity. In this study, we report a low-cost solid-state electrolyte, Li_xAlCl_3-xO_x (0.6 ≤ x ≤ 1.1), with dramatically enhanced ionic conductivity achieved through the construction of fast ion-conducting channels via an innovative anion mixing strategy. First-principles calculations and experimental characterizations reveal that the Cl⁻/O²⁻ anion mixing expands the distribution of Li⁺ ions within the lattice while reducing the distance between adjacent sites. This structural optimization results in a low Li⁺ migration activation energy of 0.3 eV and elevates the ionic conductivity from 10⁻³ mS/cm to 1.5 mS/cm. Furthermore, the Cl^-/O^2- mixing synergistically combines the advantages of both anions, endowing the Li_xAlCl_3-xO_x electrolyte with high-voltage stability (up to 3.96 V vs. Li⁺/Li), robust interfacial compatibility, and air stability. When integrated into all-solid-state batteries with a LiCoO₂Li_0.8AlCl_2.2O_0.8Li₆PS₅ClLi-Si configuration, it delivers an initial capacity of 127 mAh/g and retains 94.4% of its discharge capacity after 180 cycles at 0.3 C.

Piezoelectric materials have wide commercial applications involving our everyday lives. The common categorized "soft" and "hard" piezoelectric materials have distinct even contradictory performance parameters typically exemplified by piezoelectric coefficient d₃₃ and mechanical quality factor Q_m. However, for some special devices operated in resonant mode, simultaneously high or at least balanced performance parameters are needed. Here, we show the transition from "soft" to "hard" performance in 2 mol% Sm doped (0.36-x)Pb(Ni_1/3Nb_2/3)O₃-xPb(Mn_1/3Nb_2/3)O₃–0.28PbZrO₃–0.36PbTiO₃ quaternary solid solution piezoceramics, for which the d₃₃ and planar electromechanical coupling factor k_p decrease, while Q_m and Curie temperature T_c increase monotonously with increasing x value. As the results, balanced performance with moderate d₃₃ = 446 pC/N, k_p = 0.49, Q_m = 425, and T_c = 170 ℃ are achieved around x = 0.03. This work not only shows the feasibility for combining "soft" and "hard" performance by forming appropriate solid solutions, but also provides a suitable material basis for further simultaneously optimizing piezoelectric parameters.