Recently, incorporating nitrogen (N) and/or carbon (C) elements into the metal oxide matrix has been considered a promising strategy to enhance the electrochemical performance of supercapacitors (SCs) as they improve the wettability and conductivity properties. Herein, we synthesized N- and C-rich core-shell-like nickel oxide-nickel carbide (N/C-Ni2O3@Ni3C) composite materials by adopting facile wet chemical approaches, followed by the calcination in the N2 atmosphere. The obtained material exhibited elongated square bipyramidal-like nanostructures. With the synergistic effects of both the core- and shell-like active materials, the optimized N/C-Ni2O3@Ni3C-0.5 (0.5 g of polyvinylpyrrolidone) composite material demonstrated good electrochemical performance with a considerable specific capacity of 199.4 mAh g−1 at 2 A g−1 and sustained 5000 charge-discharge cycles by retaining 98.7% of its capacity at 7 A g−1. To explore the practical applicability of the prepared material, a hybrid SC (HSC) was constructed with N/C-Ni2O3@Ni3C-0.5 (positive electrode) and activated carbon (negative electrode). The HSC with the voltage window of 1.6 V exhibited the specific capacitance of 142.3 F g−1, and the maximum energy and power densities of 49.28 Wh kg−1 and 5750 W kg−1, respectively. The capability of HSC to power different electronic appliances was also demonstrated.

Evolving cost-effective transition metal phosphides (TMPs) using general approaches for energy storage is pivotal but challenging. Besides, the absence of noble metals and high electrocatalytic activity of TMPs allow their applicability as catalysts in oxygen evolution reaction (OER). Herein, CoNiP‒CoP2 (CNP‒CP) composite is in situ deposited on carbon fabric by a one-step hydrothermal technique. The CNP‒CP reveals hybrid nanoarchitecture (3D-on-1D HNA), i.e., cashew fruit-like nanostructures and nanocones. The CNP‒CP HNA electrode delivers higher areal capacity (82.8 μAh cm–2) than the other electrodes. Furthermore, a hybrid cell assembled with CNP‒CP HNA shows maximum energy and power densities of 31 μWh cm–2 and 10.9 mW cm–2, respectively. Exclusively, the hybrid cell demonstrates remarkable durability over 30 000 cycles. In situ/operando X-ray absorption near-edge structure analysis confirms the reversible changes in valency of Co and Ni elements in CNP‒CP material during real-time electrochemical reactions.  Besides, a quasi-solid-state device unveils its practicability by powering electronic components. Meanwhile, the CNP‒CP HNA verifies its higher OER activity than the other catalysts by revealing lower overpotential (230 mV). Also, it exhibits relatively small Tafel slope (38 mV dec–1) and stable OER activity over 24 h. This preparation strategy may initiate the design of advanced TMP-based materials for multifunctional applications.

Nanogenerators have attracted much attention in the past few years due to their high conversion efficiency of mechanical energy into electrical energy that is abundantly available in the environment and everyday human life. Enhancing the electrical output performance of nanogenerator using composite polymeric films (CPFs), i.e., piezoelectric materials embedded in triboelectric polymers, has gained potential interest. The CPFs can provide a high relative permittivity and enhanced surface charge density, resulting in an enhanced electrical output. Herein, piezoelectric zinc oxide (ZnO) nanoflakes (ZnO-NFs) were synthesized by a hydrothermal reaction process and combined with a nylon polymer to prepare a positive triboelectric composite film. Furthermore, a piezo/triboelectric hybrid nanogenerator (ZnO-HNG) was fabricated with the prepared nylon/ZnO composite film as a positive triboelectric material and PDMS as a negative triboelectric material, respectively. The effect of the loading concentration of the ZnO-NFs in the nylon polymer on the electrical output was systematically investigated. The optimized ZnO-HNG exhibited a stable and enhanced electrical output performance with the voltage, current, charge density, and power density values of ≈300 V, ≈9 µA, ≈85 μC m−2, and ≈4.5 W m−2, respectively. Finally, the ZnO-HNG was attached to the human body to harvest various mechanical motions involved in everyday human life and power various low-power portable electronics.

A solid electrolyte interphase (SEI) on a sodium (Na) metal anode strongly affects the Na deposition morphology and the cycle life of Na metal batteries (SMBs). SMB applications are hindered by an unstable SEI and dendrite growth on the Na anode surface, which directly cause low coulombic efficiency and can even lead to safety issues. An artificial interface layer can stabilize Na metal anodes, be easily tailored, and is barely affected by electrochemical processes. In this review, recent advances that support the stability of working Na metal anodes are focused via artificial interphase engineering of inorganic materials, organic materials, and organic–inorganic composite materials, with an emphasis on the significance of interface engineering in SMBs. Fundamental investigations of artificial interphase engineering are also discussed on Na metal anodes and some recent research is summarized to enhance the interface between Na metal and electrolytes using an artificial interface layer. The prospects for interphase chemistry for Na metal anodes are provided to open a way to safe, high-energy, next-generation SMBs.

Present work successfully demonstrates the synthesis of ion diffused ant colony-like porous carbon structure (PSWC) with high surface roughness from seaweed using a facile pre-carbonization NaCl treatment, followed by carbonization at 800°C. X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy studies confirm the retention of natural redox groups such as pyrrolic N, pyridinic N, oxidized sulfur, carboxyl, Fe3+, and Zn2+ and the diffusion of Na+ and Cl− ions in the PSWC. The electrochemical analysis of PSWC reveals that NaCl treatment further enhances the performance, and the redox groups and transition metal ions facilitate the faradic battery-type energy storage with an excellent specific capacitance of 904.44 F g−1 at 1 A g−1 of current density in a classic three-electrode system. The fabricated polyvinyl alcohol-potassium hydroxide gel electrolyte-based quasi-solid-state asymmetric supercapacitor device exhibits good energy density and power density of 52.15 Wh kg−1 and 362.14 W Kg−1, respectively with a superior cyclic life (98.94% capacitance retention after 10 000 cycles). The overall eco-friendliness, low cost, availability, facile synthesis process, sustainability, facile upscale synthesis, and excellent electrochemical properties provide a potential application of PSWC in advanced energy storage systems.

The sphere of activity between the wildlife and human has been more overlapped with the enlarged infrastructure. With using the energy harvesting-storage technology, the warning signal can be easily generated and transmitted to the wildlife by a light stimulation. Here, the hybrid energy harvester with a triboelectric nanogenerator and a plate-typed thermoelectric generator is integrated with a gold nanoflower-based supercapacitor for directly storing energy. 23.7 V of the VOC and 0.86 μA of the ISC are generated through the triboelectric nanogenerator. For the thermoelectric generator, 40 mV and 10 mA of each electrical output are generated with the temperature difference of 6°C. The hybrid generator is optimized by changing the connection and adding components for the highest charging speed. The electrochemical characteristics of the supercapacitor are demonstrated with the cyclic voltammetry and discharging time in the galvanostatic charge-discharge test. After storing the generated energy into the fabricated supercapacitor, an external photo-sensing system is stimulated by an LED light operated by the stored electrical energy. By harvesting energy from the wildlife, the ability for providing an optical warning signal to the animals can be successfully demonstrated and open up a new field of ecologically friendly technology.