The asymmetric coordination engineering of single-atom catalysts emerges as a promising strategy to accelerate the sluggish redox kinetics of sulfur cathodes in Li–S batteries. Herein, an asymmetric coordination of Fe single-atom catalyst was exploited by simultaneously introducing sulfur atom and nitrogen atoms into the first coordination shell, where each Fe atom was connected with one sulfur and three nitrogen atoms (FeN₃S₁). This asymmetric coordination redistributed the electron density around the Fe center, which upshifted the d-band center and shortened the Fe–S(ads) bond length between the Fe site and lithium polysulfides (LiPSs), collectively strengthening LiPSs adsorption (where (ads) denotes the adsorbed atom). Moreover, these electronic modulations endowed the asymmetric FeN₃S₁ site, lowering the free energy barriers of the rate-determining steps (Li₂S₄ to Li₂S₂/Li₂S), accelerating the sulfur redox kinetics. Consequently, the S@Fe,S-NC^15-1 (NC stands for nitrogen-doped carbon) cathode maintains a low capacity decay rate of only 0.05% per cycle over 500 cycles at 4.0 C. This work provides a rational asymmetric coordination engineering strategy toward high performance Li–S batteries.

Sodium titanium phosphate (NaTi₂(PO₄)₃, NTP) has emerged as a promising electrode material due to its three-dimensional open framework. This study investigates the use of NTP in aqueous dilute Li⁺/Na⁺ electrolytes and extends its application to high-concentration K⁺ electrolytes. X-ray photoelectron spectroscopy, X-ray absorption near-edge structure analysis, and density functional theory calculations revealed that highly electronegative fluorine partially substitutes for oxygen in the NTP lattice, resulting in the formation of Ti-F bonds. The substitution effectively modulates the electronic structure of Ti⁴⁺, alters the local coordination environment, and influences the redox dynamics. Enhanced long-term cycling stability and rate performance were demonstrated across aqueous sodium-ion, lithium-ion, and potassium-ion half-cells. Among the investigated systems, the aqueous sodium-ion system exhibited the best electrochemical performance, characterized by a single, well-defined charge–discharge plateau, stable cycling behavior with 88.7% capacity retention after 500 cycles at 1 A g⁻¹, and an initial specific discharge capacity of 121.7 mAh g⁻¹ at 0.2 A g⁻¹. The results establish F-doped NTP as a promising candidate for advanced energy storage applications in aqueous alkali metal-ion batteries.

Graphene-doped CuO (rGO-CuO) nanocomposites with flower shapes were prepared by an improved solvothermal method. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and UV–visible spectroscopy. The active species in the degradation reaction of rGO-CuO composites under ultrasonic irradiation were detected by electron paramagnetic resonance. On the basis of comparative experiments, the photodegradation mechanisms of two typical dyes, Rhodamine B (Rh B) and methyl orange (MO), were proposed. The results demonstrated that the doped CuO could improve the degradation efficiency. The catalytic degradation efficiency of rGO-CuO (2:1) to rhodamine B (RhB) and methyl orange (MO) reached 90% and 87% respectively, which were 2.1 times and 4.4 times of the reduced graphene oxide. Through the first-principles and other theories, we give the reasons for the enhanced catalytic performance of rGO-CuO: combined with internal and external factors, rGO-CuO under ultrasound could produce more hole and active sites that could interact with the OH· in pollutant molecules to achieve degradation. The rGO-CuO nanocomposite has a simple preparation process and low price, and has a high efficiency of degrading water pollution products and no secondary pollution products. It has a low-cost and high-efficiency application prospect in water pollution industrial production and life.

Photocatalytic reduction of CO₂ is considered as a kind of promising technologies for solving the greenhouse effect. Herein, a novel hybrid structure of g-C₃N₄/ZnO/Ti₃C₂ photocatalysts was designed and fabricated to investigate their abilities for CO₂ reduction. As demonstration, heterojunction of g-C₃N₄/ZnO can improve photogenerated carriers' separation, the addition of Ti₃C₂ fragments can further facilitate the photocatalytic performance from CO₂ to CO. Hence, g-C₃N₄/ZnO/Ti₃C₂ has efficiently increased CO production by 8 and 12 times than pristine g-C₃N₄ and ZnO, respectively. Which is ascribed to the photogenerated charge migration promoted by metallic Ti₃C₂. This work provides a guideline for designing efficient hybrid catalysts on other applications in the renewable energy fields.

Aqueous zinc-ion batteries (AZIBs) are regarded as promising electrochemical energy storage devices owing to its low cost, intrinsic safety, abundant zinc reserves, and ideal specific capacity. Compared with other cathode materials, manganese dioxide with high voltage, environmental protection, and high theoretical specific capacity receives considerable attention. However, the problems of structural instability, manganese dissolution, and poor electrical conductivity make the exploration of high-performance manganese dioxide still a great challenge and impede its practical applications. Besides, zinc storage mechanisms involved are complex and somewhat controversial. To address these issues, tremendous efforts, such as surface engineering, heteroatoms doping, defect engineering, electrolyte modification, and some advanced characterization technologies, have been devoted to improving its electrochemical performance and illustrating zinc storage mechanism. In this review, we particularly focus on the classification of manganese dioxide based on crystal structures, zinc ions storage mechanisms, the existing challenges, and corresponding optimization strategies as well as structure–performance relationship. In the final section, the application perspectives of manganese oxide cathode materials in AZIBs are prospected.