2-Azabicyclo[2.1.1]hexanes (aza-BCHs) are constrained pyrrolidine analogues with improved physicochemical characteristics in drug design. Here, we report a direct visible light-mediated photocycloaddition of 4-aza-coumarins with mono- or disubstituted bicyclo[1.1.0]butanes for synthesizing aza-BCHs without an external catalyst. The introduction of the ester group on 4-azacoumarin is critical for direct imine excitation and versatile synthetic utility. Preliminary mechanistic studies indicated that the reaction took place primarily at the triplet hypersurface.

Boron-doped diamond (BDD) is a well-known anode material with a high pollutant degradation ability for electrochemical oxidation wastewater treatment. Nevertheless, the cost of production and mechanical strength of BDD membranes remain unsatisfactory. Magnetic BDD particles derived from industrial waste may represent a promising alternative to BDD membranes, although the challenge remains in assembling these particles into a usable electrode. In this study, magnetic BDD particles were attracted to a Ti/RuO₂-IrO₂ electrode using a magnet, thus constituting a novel 2.5-dimensional (2.5D) electrode. To ascertain the structure-activity relationship of the novel electrode, essential characterizations, multi-physics simulations, pollutant degradation and electrosynthesis experiments were conducted. The results indicate that an appropriate quantity of BDD particles (0.1 g/cm²) can enhance the number of active sites by approximately 20%. A strong synergistic effect was observed between the Ti/RuO₂-IrO₂ and BDD particles in the degradation of various pollutants, including azo dye, p-benzoquinone, succinic acid and four kinds of real wastewaters, as well as glycerol conversion. The joint active sites on the interface between Ti/RuO₂-IrO₂ and BDD particles, as well as the inner active sites on BDD particles, have been identified as crucial in the mineralization of pollutants and the generation of value-added products. The optimal amount of BDD particles (0.1 g/cm²) is sufficient to preserve the joint active sites and to maintain an adequate polarization on the BDD particles. Nevertheless, the hybrid feature of the 2.5D electrode is diminished when a greater quantity of BDD particles (0.3 g/cm²) is loaded.

Electrochemical water splitting presents a promising, environmentally friendly alternative to fossil fuels for hydrogen production. However, the efficiency is constrained by the sluggish kinetics and high overpotentials associated with the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). While noble metal catalysts, such as Pt for HER and Ir for OER, currently offer superior performance, their widespread adoption is hindered by high cost and scarcity. This has spurred research into cost-effective alternatives, with a focus on understanding the underlying electrocatalytic mechanisms. MXenes, a class of two-dimensional materials, have emerged as promising candidates for electrocatalytic water splitting due to their unique physical and chemical properties. However, research in this field remains largely experimental, lacking a comprehensive understanding of fundamental mechanisms. This knowledge gap impedes the development of high-efficiency electrocatalysts and necessitates further investigation. This review systematically examines recent advancements in MXene-based nanohybrids for electrocatalytic water splitting, covering synthetic methods, structure-property relationships, and performance enhancement strategies. It encompasses both precious and non-noble metal-based systems for HER, OER, and overall water splitting applications. Additionally, this review addresses current challenges, opportunities, and future research directions for MXene-based nanohybrids. By providing comprehensive insights into the development of high-performance MXene-based electrocatalysts, this review aims to accelerate progress in the field of electrochemical water splitting. It serves as a valuable resource for researchers and engineers working towards more efficient and sustainable hydrogen production technologies, potentially contributing to the broader goal of transitioning away from fossil fuels towards cleaner energy sources.

For large-scale energy storage devices, all-solid-state sodium-ion batteries (SIBs) have been revered for the abundant resources, low cost, safety performance and a wide operating temperature range. Na-ion solid-state electrolytes (Na-ion SSEs) are the critical parts and mostly determine the electrochemical performance of SIBs. Among the studied ones, inorganic Na-ion SSEs stand out for their good safety performance and high ionic conductivity. In this review, we outline the research progress of inorganic SSEs in SIBs based on the perspectives of crystal structure, performance optimization, synthesis methods, all-solid-state SIBs, interface modification and related characterization techniques. We hope to provide some ideas for the design of future high-performance Na-ion SSEs.

Solid-state batteries (SSBs) with thermal stable solid-state electrolytes (SSEs) show intrinsic capacity and great potential in energy density improvement. SSEs play critical role, however, their low ionic conductivity at room temperature and high brittleness hinder their further development. In this paper, polypropylene (PP)-polyvinylidene fluoride (PVDF)-Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP)-Lithium bis(trifluoromethane sulphonyl)imide (LiTFSI) multi-layered composite solid electrolyte (CSE) is prepared by a simple separator coating strategy. The incorporation of LATP nanoparticle fillers and high concentration LiTFSI not only reduces the crystallinity of PVDF, but also forms a solvation structure, which contributes to high ionic conductivity in a wide temperature. In addition, using a PP separator as the supporting film, the mechanical strength of the electrolyte was improved and the growth of lithium dendrites are effectively inhibited. The results show that the CSE prepared in this paper has a high ionic conductivity of 6.38×10^–4 S/cm at room temperature and significantly improves the mechanical properties, the tensile strength reaches 11.02 MPa. The cycle time of Li/Li symmetric cell assembled by CSE at room temperature can exceed 800 h. The Li/LFP full cell can cycle over 800 cycles and the specific capacity of Li/LFP full cell can still reach 120 mAh/g after 800 cycles at 2 C. This CSE has good cycle stability and excellent mechanical strength at room temperature, which provides an effective method to improve the performance of solid electrolytes under moderate condition.

Flexible zinc-ion batteries (FZIBs) have been acknowledged as a potential cornerstone for the future development of flexible energy storage, yet conventional FZIBs still encounter challenges, particularly concerning performance failure at low temperatures. To address these challenges, a novel anti-freezing leather gel electrolyte (AFLGE-30) is designed, incorporating ethanol as a hydrogen bonding acceptor. The AFLGE-30 demonstrates exceptional frost resistance while maintaining favorable flexibility even at −30 ℃; accordingly, the battery can achieve a high specific capacity of about 70 mAh/g. Cu//Zn battery exhibits remarkable stability at room temperature, retaining ~96% efficiency after 120 plating/stripping cycles at 1 mA/cm². Concurrently, the Zn//Zn symmetric batteries demonstrate a lifespan of 4100 h at room temperature, which is attributed to the enhancement of Zn²⁺ deposition kinetics, restraining the formation of zinc dendrites. Furthermore, FZIBs exhibit minimal capacity loss even after bending, impacting, or burning. This work provides a promising strategy for designing low-temperature-resistant FZIBs.

With the development of science and technology, there is an increasing demand for energy storage batteries. Aqueous zinc-ion batteries (AZIBs) are expected to become the next generation of commercialized energy storage devices due to their advantages. The aqueous zinc ion battery is generally composed of zinc metal as the anode, active material as the cathode, and aqueous electrolyte. However, there are still many problems with the cathode/anode material and voltage window of the battery, which limit its use. This review introduces the recent research progress of zinc-ion batteries, including the advantages and disadvantages, energy storage mechanisms, and common cathode/anode materials, electrolytes, etc. It also gives a summary of the current research status of each material and provides solutions to the problems they face. Finally, it looks at the future direction and methods to optimize the performance of zinc-ion full batteries.

Rationally design the morphology and structure of electroactive nanomaterials is an effective approach to enhance the performance of aqueous batteries. Herein, we co-engineered the hollow architecture and interlayer spacing of layered double hydroxides (LDH) to achieve high electrochemical activity. The hierarchical hollow LDH was prepared from bimetallic zeolitic imidazolate frameworks (ZIF) by a facile cation exchange strategy. Zn and Cu elements were selected as the second metals incorporated in Co-ZIF. The characteristics of the corresponding derivatives were studied. Besides, the transformation mechanism of CoZn-ZIF into nanosheet-assembled hollow CoZnNi LDH (denoted as CoZnNi-OH) was systematically investigated. Importantly, the interlayer spacing of CoZnNi-OH expands due to Zn²⁺ incorporation. The prepared CoZnNi-OH offers large surface area, exposed active sites, and rapid mass transfer/diffusion rate, which lead to a significant enhancement in the specific capacitance, rate performance, and cycle stability of CoZnNi-OH electrode. In addition, the aqueous alkaline CoZnNi-OH//Zn showed a maximum energy density/power density of 0.924 mWh/cm², 8.479 mW/cm². This work not only raises an insightful strategy for regulating the morphology and interlayer spacing of LDH, but also provides a reference of designing hollow nickel-based nanomaterials for aqueous batteries.

Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport. The construction of these unique structures always requires new self-assembly behaviors with different building blocks, intriguing phenomena of colloidal chemistry. In this work, by delicately balancing the electrostatic repulsions between 2D inorganic nanosheets and the electrostatic adsorption with cations, we develop a general strategy to fabricate stable free-standing 1T molybdenum disulphide (MoS₂) hydrogel membranes with abundant fluidic channels. Given the interpenetrating ionic transport network, the MoS₂ hydrogel membranes exhibit a high-level capacitive performance 1.34 F/cm² at an ultrahigh mass loading of 11.2 mg/cm². Furthermore, the interlayer spacing of MoS₂ in the hydrogel membranes can be controlled with ångström-scale precision using different cations, which can promote further fundamental studies and potential applications of the transition-metal dichalcogenides hydrogel membranes.

Despite significant progress has been achieved regarding the shuttle-effect of lithium polysulfides, the suppressed specific capacity and retarded redox kinetics under high sulfur loading still threat the actual energy density and power density of lithium-sulfur batteries. In this study, a graham condenser-inspired carbon@WS₂ host with coil-in-tube structure was designed and synthesized using anodic aluminum oxide (AAO) membrane with vertically aligned nanopores as template. The vertical array of carbon nanotubes with internal carbon coils not only leads to efficient charge transfer across through the thickness of the cathode, but also provides significant confinement to polysulfide diffusion towards both the lateral and longitudinal directions. Few-layer WS₂ in the carbon coils perform a synergistic role in suppressing the shuttle-effect as well as boosting the cathodic kinetics. As a result, high specific capacity (1180 mAh/g at 0.1 C) and long-cycling stability at 0.5 C for 500 cycles has been achieved at 3 mg_S/cm². Impressive areal capacity of 7.4 mAh/cm² has been demonstrated when the sulfur loading reaches 8.4 mg/cm². The unique coil-in-tube structure developed in this work provides a new solution for high sulfur loading cathode towards practical lithium-sulfur batteries.