Transient Loss‐Induced Non‐Hermitian Degeneracies for Ultrafast Terahertz Metadevices

Abstract Non‐Hermitian degeneracies, also known as exceptional points (EPs), have attracted considerable attention due to their unique physical properties. In particular, metasurfaces related to EPs can open the way to unprecedented devices with functionalities such as unidirectional transmission and ultra‐sensitive sensing. Herein, an active non‐Hermitian metasurface with a loss‐induced parity‐time symmetry phase transition for ultrafast terahertz metadevices is demonstrated. Specifically, the eigenvalues of the non‐Hermitian transmission matrix undergo a phase transition under optical excitation and are degenerate at EPs in parameter space, which is accompanied by the collapse of chiral transmission. Ultrafast EP modulation on a picosecond time scale can be realized through variations in the transient loss at a non‐Hermitian metasurface pumped by pulsed excitation. Furthermore, by exploiting the physical characteristics of chiral transmission EPs, a switchable quarter‐wave plate based on the photoactive metasurface is designed and experimentally verified and realized the corresponding function of polarization manipulation. This work opens promising possibilities for designing functional terahertz metadevices and fuses EP physics with active metasurfaces

Copper/Iron-Catalyzed Aerobic Oxyphosphorylation of Terminal Alkynes Leading to β‑Ketophosphonates

A copper/iron-catalyzed oxyphosphorylation of alkynes with H-phosphonates through a radical process was developed. The present protocol provides an attractive approach to β-ketophosphonates in moderate to good yields, with the advantages of readily available substrate, high functional group tolerance and operation simplicity

Recent Advances in LDH/g-C₃N₄ Heterojunction Photocatalysts for Organic Pollutant Removal

Environmental pollution has been decreased by using photocatalytic technology in conjunction with solar energy. An efficient method to obtain highly efficient photocatalysts is to build heterojunction photocatalysts by combining graphitic carbon nitride (g-C3N4) with layered double hydroxides (LDHs). In this review, recent developments in LDH/g-C3N4 heterojunctions and their applications for organic pollutant removal are systematically exhibited. The advantages of LDH/g-C3N4 heterojunction are first summarized to provide some overall understanding of them. Then, a variety of approaches to successfully assembling LDH and g-C3N4 are simply illustrated. Last but not least, certain unmet research needs for the LDH/g-C3N4 heterojunction are suggested. This review can provide some new insights for the development of high-performance LDH/g-C3N4 heterojunction photocatalysts. It is indisputable that the LDH/g-C3N4 heterojunctions can serve as high-performance photocatalysts to make new progress in organic pollutant removal

Typical cathode materials for lithium‐ion and sodium‐ion batteries: From structural design to performance optimization

Abstract Rechargeable lithium‐ion and sodium‐ion batteries (SIB) have dominated the energy storage fields such as electric vehicles and portable electronics due to their high energy density, long cycle life, and environmental friendliness. However, the critical bottleneck hindering the further improvement of their electrochemical performance is the unsatisfactory cathode materials, typically exhibiting inherent drawbacks such as low reversible capacity, initial capacity loss, fast capacity decay, and poor rate performance. These issues are mainly attributed to changes in the internal structure of cathode materials, such as irreversible transformation of particle morphology, evolution of crystal structure, and undesired physicochemical interfacial reactions during the electrochemical process. To address above obstacles, abundant research efforts have been devoted to stabilizing the structural evolution of cathode materials and enhancing their electrochemical performance. Herein, we reviewed the research progress on the cathode materials for lithium‐ion and SIBs. The typical cathodes and their structural characteristics, electrochemical behaviors, reaction mechanisms, and strategies for electrochemical performance optimization were summarized. This review aims to promote the understanding of the structure‐performance relationship in the cathode materials and provide some guidance for the design of advanced cathode materials for lithium‐ion and SIBs from the perspective of crystal structure

Performance of the first beam on Shenguang III technical Integration Line

Technical Integration Line (TIL), which is being constructed at CAEP, is the prototype of Shenguang III fusion laser facility. Experimental results during the first integrated tests on the first line demonstrate that the laser system architecture from master oscillator through the laser amplifiers can meet the requirement of TIL engineering design. In this paper, brief introduction of TIL and main experiment results are presented