The unstable triplet excited state is a core problem when developing selfprotective room temperature phosphorescence (RTP) in carbon dots (CDs). Here, fluorine and nitrogen codoped carbon dots (FNCDs) with long-lived triplet excited states, emitting pH-stabilized blue fluorescence and pHresponsive green self-protective RTP, are reported for the first time. The self-protective RTP of FNCDs arises from n-π * electron transitions for CN/CN bonds with a small energy gap between singlet and triplet states at room temperature. Moreover, the interdot/intradot hydrogen bonds and steric protection of CF bonds reduce quenching of RTP by oxygen at room temperature. The RTP emission of FNCDs shows outstanding reversibility, while the blue fluorescence emission has good pH stability. Based on these FNCDs, a data encoding/reading strategy for advanced anticounterfeiting is proposed via time-resolved luminescence imaging techniques, as well as steganography of complex patterns.

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Water shortage is one of the most concerning global challenges in the 21st century. Solar‐inspired vaporization employing photothermal nanomaterials is considered to be a feasible and green technology for addressing the water challenge by virtue of abundant and clean solar energy. 2D nanomaterials aroused considerable attention in photothermal evaporation‐induced water production owing to their large absorption surface, strong absorption in broadband solar spectrum, and efficient photothermal conversion. Herein, the recent progress of 2D nanomaterials‐based photothermal evaporation, mainly including emerging Xenes (phosphorene, antimonene, tellurene, and borophene) and binary‐enes (MXenes and transition metal dichalcogenides), is reviewed. Then, the optimization strategies for higher evaporation performance are summarized in terms of modulation of the intrinsic photothermal performance of 2D nanomaterials and design of the complete evaporation system. Finally, the challenges and prospective of various kinds of 2D photothermal nanomaterials are discussed in terms of the photothermal performance, stability, environmental influence, and cost. One important principle is that solutions for water challenges should not introduce new environmental and social problems. This Review aims to highlight the role of 2D photothermal nanomaterials in solving water challenges and provides a viable scheme toward the practical use in photothermal materials selection, design, and evaporation systems building.

the best candidate for prospective application on account of their low cost, easy synthesis, and renewability. Although already commercialized in LIBs, graphite cannot be formed binary intercalation compounds with sodium unless appropriate electrolyte, like diglyme-based [10] or etherbased [11] electrolyte, is employed.Therefore, hard carbon as a typical nongraphitic carbon has become a research hotspot. Normally, the capacities of hard carbon in SIBs originate from two parts: slope capacity above 0.1 V and plateau capacity below 0.1 V. As first proposed by Stevens and Dahn, the sodium storage behaviors of hard carbons were defined as "house of cards" model. [12] Namely, the slope and plateau capacities correspond to Na intercalation between graphene layers and nanopore filling/nanoplating, respectively. However, Cao et al. [13] indicated that the slope capacity is due to adsorption of Na at vacancies and the plateau capacity is attributed to Na + deintercalation behavior between graphite layers, which was further verified by other researchers. [14] In a word, the Na + storage mechanism can be summarized as (1) intercalation between the graphene layers, (2) storage in the defective turbostratic structure, (3) adsorption on the surface, and (4) filling in nanopores. Based on these mechanisms, tremendous efforts, including optimizing calcination temperature, [5,15] expanding interlayer lattice distance, [16] increasing specific surface area, [17] have been used to improve the electrochemical performance of hard carbon. In addition, doping covalent heteroatom (e.g., N, [18] S, [16,19] and F [20] ) is another efficient way to elevate sodium storage capacity by enhancing Na adsorption capability and electronic conductivity. However, these carbon anodes generally have two characteristics, namely the large specific surface area and high voltage plateau, which lead to the formation of excess and undesirable solid electrolyte interface (SEI) and thus limiting the practical utilization.To avoid these issues, we adopt electrospinning technology to fabricate phosphorous-functionalized hard carbon with low specific surface area and low operation potential, aiming at maximizing the desodiation capacity and further improving the energy density. Phosphorous as a nonmetallic chemical element has already been used in SIBs reported by Yang and co-workers [9a] due to its high theoretical specific capacity of 2596 mA h g −1 . Similar to N or S atoms, P can also serve as electron donors doped into carbon to induce a shift of the Fermi level to the conducting band. Nevertheless, it is very difficult Hard carbon as a typical anode material for sodium ion batteries has received much attention in terms of its low cost and renewability. Herein, phosphorusfunctionalized hard carbon with a specific "honeycomb briquette" shaped morphology is synthesized via electrospinning technology. When applied as an anode material for Na + storage, it exhibits an impressively high reversible capacity of 393.4 mA h g −1 with the capacity retention up to 9...

The electron-selective layer (ESL) is an indispensable component of perovskite solar cells (PSCs) and is responsible for the collection of photogenerated electrons. Preparing ESL at a low temperature is significant for future fabrication of flexible PSCs. In this work, solution-processed amorphous WO(x) thin film was prepared facilely at low temperature and used as ESL in PSCs. Results indicated that a large quantity of nanocaves were observed in the WO(x) thin film. In comparison with the conventional TiO2 ESL, the WO(x) ESL exhibited comparable light transmittance but higher electrical conductivity. Compared with the TiO2-based PSCs, PSCs that use WO(x) ESL exhibited comparable photoelectric conversion efficiency, larger short-circuit current density, but lower open-circuit voltage. Electrochemical characterization indicated that the unsatisfied open-circuit voltage and fill factor were caused by the inherent charge recombination. This study demonstrated that this material is an excellent candidate for ESL.

(circular birefringence) and absorption losses (circular dichroism) with the circu larly polarized light (CPL) illumination. [10] CB arises from the difference in the real part of refractive index, leading to a dif ferent velocity for LCP and RCP compo nents, and thus results in the polarization rotation of the linearly polarized incident light. CD corresponds to the difference in the imaginary part of refractive index, resulting in a distinct absorption loss for LCP and RCP excitations. Besides the con ventional CD and CB, asymmetric trans mission (circular conversion dichroism) is another fundamental chiroptical pheno menon, which exists in the nondiffracting array, referring to different LCPtoRCP and RCPtoLCP conversion efficiencies. [11] All of these chiroptical phenomena have been successfully applied in the spectros copy for identifying special arrangements of chiral matters in biology, chemistry and physics as efficient diagnostic tools. [12][13][14][15][16] However, the chirop tical response in natural chiral materials is relatively weak due to the small electromagnetic (EM) interaction volume, [17] hence limits its further applications.Recent progress in plasmonics paves the way for the enhancement of chiroptical response. [18][19][20] Surface plasmons (SPs), as the collective electrons oscillation at the dielectric and metal interface, [21][22][23] present the capacity of light confine ment and field enhancement, which significantly improve the strength of lightmatter interactions. [24][25][26][27][28] With the uptodate nanofabrication technology, the study field of chirality has been extended from traditional chiral molecules to 3D metallic nanostructures. [29][30][31][32] Chiroptical responses of metallic meta molecules have been widely investigated, [33][34][35] and applied in various fields, such as biosensing, [36] chiral catalysis, [37] polari zation tuning, [38] and chiral photo detection.[39] The 3D metallic structure exhibited giant optical activity response because of the strong interaction between electric and magnetic resonant modes. [40,41] Different from 3D chiral ensembles, planar chiral structures show none chiral effect, as they can always coincide with their mirror images. However, 2D chirality was successfully found in the quasitwodimensional (quasi2D) chiral structure. [42] Moreover, recent reports show that even achiral nanomaterials have the ability to generate strong CD under an oblique CPL illumination. [43] This kind of extrinsic chirality arises from sym metry breaking of the incident light and the quasi2D material, which is quite different from the intrinsic chirality of 3D chiral The plasmonic chiroptical effect has been used to manipulate chiral states of light, where the strong field enhancement and light localization in metallic nanostructures can amplify the chiroptical response. Moreover, in metamaterials, the chiroptical effect leads to circular dichroism (CD), circular birefringence (CB), and asymmetric transmission. Potential applications enabled by chiral plasmonics...

Phosphorene has attracted great interest due to its unique electronic and optoelectronic properties owing to its tunable direct and moderate band-gap in association with high carrier mobility. However, its intrinsic instability in air seriously hinders its practical applications, and problems of technical complexity and in-process degradation exist in currently proposed stabilization strategies. A facile pathway in obtaining and stabilizing phosphorene through a one-step, ionic liquid-assisted electrochemical exfoliation and synchronous fluorination process is reported in this study. This strategy enables fluorinated phosphorene (FP) to be discovered and large-scale, highly selective few-layer FP (3-6 atomic layers) to be obtained. The synthesized FP is found to exhibit unique morphological and optical characteristics. Possible atomistic fluorination configurations of FP are revealed by core-level binding energy shift calculations in combination with spectroscopic measurements, and the results indicate that electrolyte concentration significantly modulates the fluorination configurations. Furthermore, FP is found to exhibit enhanced air stability thanks to the antioxidation and antihydration effects of the introduced fluorine adatoms, and demonstrate excellent photothermal stability during a week of air exposure. These findings pave the way toward real applications of phosphorene-based nanophotonics.

This article demonstrates a significant broadband enhancement of light absorption and improvement of photon-generated-charge transfer in CH3NH3PbI3 perovskite solar cells by incorporating plasmonic Au–Ag alloy popcorn-shaped nanoparticles (NPs).