2D metallic TaS is acting as an ideal platform for exploring fundamental physical issues (superconductivity, charge-density wave, etc.) and for engineering novel applications in energy-related fields. The batch synthesis of high-quality TaS nanosheets with a specific phase is crucial for such issues. Herein, the successful synthesis of novel vertically oriented 1T-TaS nanosheets on nanoporous gold substrates is reported, via a facile chemical vapor deposition route. By virtue of the abundant edge sites and excellent electrical transport property, such vertical 1T-TaS is employed as high-efficiency electrocatalysts in the hydrogen evolution reaction, featured with rather low Tafel slopes ≈67-82 mV dec and an ultrahigh exchange current density ≈67.61 µA cm . The influence of phase states of 1T- and 2H-TaS on the catalytic activity is also discussed with the combination of density functional theory calculations. This work hereby provides fundamental insights into the controllable syntheses and electrocatalytic applications of vertical 1T-TaS nanosheets achieved through the substrate engineering.

offer a high power density to meet the demand in rapid charge-discharge applications. [6][7][8][9] Supercapacitors exhibit higher power densities and long cycling lifespans, but are limited by the chemical and electrochemical stability of the electrolytes, as well as a relatively low operating voltage. [10][11][12][13] Polymer film capacitors possess the advantages of low cost, facile fabrication, excellent flexibility, and high operating voltage, display the highest power densities in comparison with batteries and supercapacitors, and are widely used in electronic devices and power systems. [14][15][16][17][18] Although the state-of-the-art capacitor film represented by biaxially oriented poly propylene (BOPP) exhibits ultrahigh charge-discharge efficiency, the energy density has been significantly limited by its low dielectric constant (K), which is only about 1-2 J cm −3 . [19] To address this issue, ferroelectric polymers represented by poly(vinylidene fluoride) (PVDF) and its copolymers and terpolymers with relatively high K (≥10) have been regarded as the most promising polymeric materials for high-energy-density film capacitors. [16][17][18][19][20][21][22][23] More importantly, since capacitors can contribute more than 25% of the volume and weight to the electric power systems, the dramatic improvement of energy density of film capacitors will help to reduce the volume, weight, and cost of electronic devices, hybrid electric vehicles, etc. [24,25] The K value of ferroelectric polymers, however, is still considerably low in comparison with those of ceramic dielectrics (e.g., K of 10 4 -10 5 ) for capacitive energy storage, though these ceramics suffer from low dielectric-breakdown strength (E b ) and poor scalability. [26][27][28][29] Thus, a composite approach has been developed to improve energy-storage capability via introducing high-K inorganic fillers into ferroelectric polymers with high E b and facile processability. For dielectric polymer nanocomposites, the total stored energy densities, which are the sum of the energy densities of the ceramic filler and the polymer phases, are derived from, where U d is the energy density, f 1 is the volume fraction of the ceramic filler, f 2 is the volume fraction of the polymer matrix, and g is the interfacial area between the filler and the polymer. As ferroelectric polymers have the highest energy densities among the known dielectric polymers, they have been considered as the material of choice as polymer-matrix candidates for dielectric polymer nanocomposites. Moreover, the relatively high K values of ferroelectric polymers help to alleviate local field distortion in the The introduction of inorganic components into a polymer matrix to form polymer composites is an emerging and promising approach to dielectric materials for capacitive energy storage. Ferroelectric polymers are particularly attractive as matrices for dielectric polymer composites owing to their highest dielectric constant (≥10) among the known polymers. Here, the important aspects and recent ...

The exploration of high‐energy‐density electrostatic capacitors capable of operating both efficiently and reliably at elevated temperatures is of great significance in order to meet advanced power electronic applications. The energy density of a capacitor is strongly dependent on dielectric constant and breakdown strength of a dielectric material. Here, we demonstrate a class of solution‐processable polymer nanocomposites exhibiting a concurrent improvement in dielectric constant and breakdown strength, which typically show a negative correlation in conventional dielectric materials, along with a reduction in dielectric loss. The excellent performance is enabled by the elegant combination of nanostructured barium titanate and boron nitride fillers with complementary functionalities. The ternary polymer nanocomposite with the optimized filler compositions delivers a discharged energy density of 2.92 J cm−3 and a Weibull breakdown strength of 547 MV m−1 at 150°C, which are 83% and 25%, respectively, greater than those of the pristine polymer. The conduction behaviors including interfacial barrier and carrier transport process have been investigated to rationalize the energy storage performance of ternary polymer nanocomposite. This contribution provides a new design paradigm for scalable high‐temperature polymer film capacitors.