Highly Controllable Surface Plasmon Resonance Property by Heights of Ordered Nanoparticle Arrays Fabricated <i>via</i> a Nonlithographic Route

Perfectly ordered nanoparticle arrays are fabricated on large-area substrates (>cm²) <i>via</i> a cost-effective nonlithographic route. Different surface plasmon resonance (SPR) modes focus consequently on their own positions due to the identical shape and uniform size and distance of these plasmonic metallic nanoparticles (Ag and Au). On the basis of this and FDTD (finite-difference time-domain) simulation, this work reveals the variation of all SPR parameters (position, intensity, width, and mode) with nanoparticle heights, which demonstrates that the effect of heights are different in various stages. On increasing the heights, the major dipole SPR mode precisely blue-shifts from the near-infrared to the visible region with intensity strengthening, a peak narrowing effect, and multipole modes excitation in the UV–vis range. The intensity of multipole modes can be manipulated to be equal to or even greater than the major dipole SPR mode. After coating conformal TiO₂ shells on these nanoparticle arrays by atomic layer deposition, the strengthening of the SPR modes with increasing the heights results in the multiplying of the photocurrent (from ∼2.5 to a maximum 90 μA cm^–2) in this plasmonic-metal–semiconductor-incorporated system. This simple but effective adjustment for all SPR parameters provides guidance for the future design of plasmonic metallic nanostructures, which is significant for SPR applications

Carrier Mobility-Dominated Gas Sensing: A Room-Temperature Gas-Sensing Mode for SnO₂ Nanorod Array Sensors

Adsorption-induced change of carrier density is presently dominating inorganic semiconductor gas sensing, which is usually operated at a high temperature. Besides carrier density, other carrier characteristics might also play a critical role in gas sensing. Here, we show that carrier mobility can be an efficient parameter to dominate gas sensing, by which room-temperature gas sensing of inorganic semiconductors is realized via a carrier mobility-dominated gas-sensing (CMDGS) mode. To demonstrate CMDGS, we design and prepare a gas sensor based on a regular array of SnO₂ nanorods on a bottom film. It is found that the key for determining the gas-sensing mode is adjusting the length of the arrayed nanorods. With the change in the nanorod length from 340 to 40 nm, the gas-sensing behavior changes from the conventional carrier-density mode to a complete carrier-mobility mode. Moreover, compared to the carrier density-dominating gas sensing, the proposed CMDGS mode enhances the sensor sensitivity. CMDGS proves to be an emerging gas-sensing mode for designing inorganic semiconductor gas sensors with high performances at room temperature

Integration of Cointercalation and Adsorption Enabling Superior Rate Performance of Carbon Anodes for Symmetric Sodium-Ion Capacitors

Carbon materials have been the most common anodes for sodium-ion storage. However, it is well-known that most carbon materials cannot obtain a satisfactory rate performance because of the sluggish kinetics of large-sized sodium-ion intercalation in ordered carbon layers. Here, we propose an integration of co-intercalation and adsorption instead of conventional simplex-intercalation and adsorption to promote the rate capability of sodium-ion storage in carbon materials. The experiment was demonstrated by using a typical carbon material, reduced graphite oxide (RGO400) in an ether-solvent electrolyte. The ordered and disordered carbon layers efficiently store solvated sodium ions and simplex sodium ions, which endows RGO400 with enhanced reversible capacity (403 mA h g–1 at 50 mA g–1 after 100 cycles) and superior rate performance (166 mA h g–1 at 20 A g–1). Furthermore, a symmetric sodium-ion capacitor was demonstrated by employing RGO400 as both the anode and cathode. It exhibits a high energy density of 48 W h g–1 at a very high power density of 10,896 W kg–1. This work updates the sodium-ion storage mechanism and provides a rational strategy to realize high rate capability for carbon electrode materials

Dibenzothiophene Derivatives: From Herringbone to Lamellar Packing Motif

It is generally believed that π−π stacking would be much more efficient than herringbone stacking for the transporting of charge carriers. The electron-withdrawing group sulphone unit was introduced into dibenzothiophene (DBT) derivatives, and lamellar structures were observed in the single crystals of the products along with strong, long-range π−π intermolecular interactions. As a contrast, the reduced materials adopted herringbone packing. We contributed this change of packing motif to the polarity of the sulphone unit. These results are meaningful to the molecular design to obtain π−π stacking

Dibenzothiophene Derivatives: From Herringbone to Lamellar Packing Motif

It is generally believed that π−π stacking would be much more efficient than herringbone stacking for the transporting of charge carriers. The electron-withdrawing group sulphone unit was introduced into dibenzothiophene (DBT) derivatives, and lamellar structures were observed in the single crystals of the products along with strong, long-range π−π intermolecular interactions. As a contrast, the reduced materials adopted herringbone packing. We contributed this change of packing motif to the polarity of the sulphone unit. These results are meaningful to the molecular design to obtain π−π stacking

Dibenzothiophene Derivatives: From Herringbone to Lamellar Packing Motif

It is generally believed that π−π stacking would be much more efficient than herringbone stacking for the transporting of charge carriers. The electron-withdrawing group sulphone unit was introduced into dibenzothiophene (DBT) derivatives, and lamellar structures were observed in the single crystals of the products along with strong, long-range π−π intermolecular interactions. As a contrast, the reduced materials adopted herringbone packing. We contributed this change of packing motif to the polarity of the sulphone unit. These results are meaningful to the molecular design to obtain π−π stacking

Extended π‑Conjugated System for Fast-Charge and -Discharge Sodium-Ion Batteries

Organic sodium-ion batteries (SIBs) are potential alternatives of current commercial inorganic lithium-ion batteries for portable electronics (especially wearable electronics) because of their low cost and flexibility, making them possible to meet the future flexible and large-scale requirements. However, only a few organic SIBs have been reported so far, and most of them either were tested in a very slow rate or suffered significant performance degradation when cycled under high rate. Here, we are focusing on the molecular design for improving the battery performance and addressing the current challenge of fast-charge and -discharge. Through reasonable molecular design strategy, we demonstrate that the extension of the π-conjugated system is an efficient way to improve the high rate performance, leading to much enhanced capacity and cyclability with full recovery even after cycled under current density as high as 10 A g^–1

Rational Design of a Hierarchical Candied-Haws-like NiCo₂O₄@Ni,Co-(HCO₃)₂ Heterostructure for the Electrochemical Performance Enhancement of Supercapacitors

Designing core–shell heterostructures with multicomponents, more electroactive sites, hierarchical structures, and stable geometrical configurations is an effective approach to enhance the electrochemical properties of supercapacitors. Herein, we report the fabrication of a hierarchical candied-haws-like NiCo2O4@NiCo-hydrocarbonate heterostructure on Ni foam (NiCo2O4@NiCo-HCs), which consists of NiCo2O4 nanowires acting as “rebars” that are tightly strung with NiCo-HC nanoparticles. The strong interfacial reaction between the NiCo2O4 “core” and the NiCo-HC “shell” accelerates the charge transfer within the heterostructure, while the hierarchical structure containing quantities of paths and pores provides fast ion diffusion throughout the whole electrode, hence remarkably boosting the electrochemical performance of a NiCo2O4@NiCo-HC electrode. As expected, the NiCo2O4@NiCo-HC electrode shows a high specific capacitance of 3216.4 F g–1 at a current density of 1 A g–1 and 2259.9 F g–1 even at 20 A g–1 (1.6-fold that of the NiCo2O4 electrode and 5.5-fold that of NiCo-HCs). In addition, an assembled asymmetric supercapacitor NiCo2O4@NiCo-HCs//AC delivers a high energy density of 47.46 Wh kg–1 at a power density of 708.94 W kg–1, together with 96.2% capacitance retention after 6000 cycles, surpassing most of the reported analogues. These results suggest that our hierarchical candied-haws-like heterostructure design is potential for the performance enhancement of supercapacitors

Highly Ordered Three-Dimensional Ni-TiO₂ Nanoarrays as Sodium Ion Battery Anodes

Sodium ion batteries (SIBs) represent an effective energy storage technology with potentially lower material costs than lithium ion batteries. Here, we show that the electrochemical performance of SIBs, especially rate capability, is intimately connected to the electrode design at the nanoscale by taking anatase TiO₂ as an example. Highly ordered three-dimensional (3D) Ni-TiO₂ core–shell nanoarrays were fabricated using nanoimprited AAO templating technique and directly used as anode. The nanoarrays delivered a reversible capacity of ∼200 mAh g^–1 after 100 cycles at the current density of 50 mAh g^–1 and were able to retain a capacity of ∼95 mAh g^–1 at the current density as high as 5 A g^–1 and fully recover low rate capacity. High ion accessibility, fast electron transport, and excellent electrode integrity were shown as great merits to obtain the presented electrochemical performance. Our work demonstrates the possibility of highly ordered 3D heterostructured nanoarrays as a promising electrode design for Na energy storage to alleviate the reliance on the materials’ intrinsic nature and provides a versatile and cost-effective technique for the fabrication of such perfectly ordered nanostructures