Nano Materials Science最新文献

Supercapacitors (SCs) are considered promising energy storge systems because of their outstanding power density, fast charge and discharge rate and long-term cycling stability. The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors. As the battery-type materials, transition metal phosphides (TMPs) possess high theoretical specific capacity, good electrical conductivity and superior structural stability, which have been extensively studied to be electrode materials for supercapacitors. In this review, we summarize the up-to-date progress on TMPs materials from diversified synthetic methods, diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors. In the end, we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.

All-solid-state batteries (ASSBs) are a class of safer and higher-energy-density materials compared to conventional devices, from which solid-state electrolytes (SSEs) are their essential components. To date, investigations to search for high ion-conducting solid-state electrolytes have attracted broad concern. However, obtaining SSEs with high ionic conductivity is challenging due to the complex structural information and the less-explored structure-performance relationship. To provide a solution to these challenges, developing a database containing typical SSEs from available experimental reports would be a new avenue to understand the structure-performance relationships and find out new design guidelines for reasonable SSEs. Herein, a dynamic experimental database containing >600 materials was developed in a wide range of temperatures (132.40–1261.60 ​K), including mono- and divalent cations (e.g., Li⁺, Na⁺, K⁺, Ag⁺, Ca²⁺, Mg²⁺, and Zn²⁺) and various types of anions (e.g., halide, hydride, sulfide, and oxide). Data-mining was conducted to explore the relationships among different variates (e.g., transport ion, composition, activation energy, and conductivity). Overall, we expect that this database can provide essential guidelines for the design and development of high-performance SSEs in ASSB applications. This database is dynamically updated, which can be accessed via our open-source online system.

The trade-off between efficiency and stability has limited the application of TiO₂ as a catalyst due to its poor surface reactivity. Here, we present a modification of a TiO₂ layer with highly stable Sub-5 nm Fe₂O₃ nanoparticles (NP) by modulating its structure-surface reactivity relationship to attain efficiency-stability balance via a voltage-assisted oxidation approach. In situ simultaneous oxidation of the Ti substrate and Fe precursor using high-energy plasma driven by high voltage resulted in uniform distribution of Fe₂O₃ NP embedded within porous TiO₂ layer. Comprehensive surface characterizations with density functional theory demonstrated an improved electronic transition in TiO₂ due to the presence of surface defects from reactive oxygen species and possible charge transfer from Ti to Fe; it also unexpectedly increased the active site in the TiO₂ layer due to uncoordinated electrons in Sub-5 nm Fe₂O₃ NP/TiO₂ catalyst, thereby enhancing the adsorption of chemical functional groups on the catalyst. This unique embedded structure exhibited remarkable improvement in reducing 4-nitrophenol to 4-aminophenol, achieving approximately 99% efficiency in 20 ​min without stability decay after 20 consecutive cycles, outperforming previously reported TiO₂-based catalysts. This finding proposes a modified-electrochemical strategy enabling facile construction of TiO₂ with nanoscale oxides extandable to other metal oxide systems.

Carbon nano additives (CNAs) are critical to achieving the unique properties of functionalized composites, however, controlling the dispersion of CNAs in material matrix is always a challenging task. In this study, a simple atomization approach was successfully developed to promote the dispersion efficiency of graphene nanoplatelets (GNPs) in cement composites. This atomization approach can be integrated with the direct, indirect and combined ultrasonic stirrings in a homemade automatic stirring-atomization device. Mechanical and microstructure tests were performed on hardened cement pastes blended with GNPs in different stirring and mixing approaches. Results show that the direct ultrasonic stirrings enabled more homogeneous dispersions of GNP particles with a smaller size for a longer duration. The atomized droplets with the mean size of ∼100 ​μm largely mitigated GNPs’ agglomerations. Monolayer GNPs were observed in the cement matrix with the strength gain by up to 54%, and the total porosity decrease by 21% in 0.3 ​wt% GNPs dosage. The greatly enhanced dispersion efficiency of GNPs in cement also raised the cement hydration. This work provides an effective and manpower saving technique toward dispersing CNAs in engineering materials with great industrialization prospects.

Grain boundaries (GBs) play a crucial role on the structural stability and mechanical properties of Cu and its alloys. In this work, molecular dynamics (MD) simulations are employed to study the effects of Fe solutes on the formation energy, excess volume, dislocations and melting behaviors of GBs in CuFe alloys. It is illustrated that Fe solute affects the structural stability of Cu GBs substantially, the formation energy of GBs is reduced, but the thickness and melting point of GBs are increased, that is, the structural stability of Cu GBs is significantly improved owing to the Fe solutes. A strong scaling law exists between the formation energy, excess volume, thickness and melting point of GBs. Therefore, Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.