Electrocoagulation (EC) method has emerged as a state-of-the-art water purifying technology. Here, a self-powered EC system is proposed using a waterwheel hybrid generator (W-HG) based on disk-type triboelectric nanogenerator (D-TENG) and electromagnetic generator (EMG). D-TENG consists of a rotator and stator based on printed circuit board (PCB) technology. With electrospinning and sintering process for polytetrafluoroethylene (PTFE) as a dielectric layer of the D-TENG, the fabricated membrane exhibits superhydrophobic property with a water contact angle of 160.5°, which allows the device to show self-cleaning property and to operate at high relative humidity. Additionally, a fractal-design based switched-capacitor-converter (FSCC) is utilized with the high-frequency and high-output based D-TENG to operate commercial electronic devices. The hybridized W-HG exhibits 1.75 mW of the average power at the matching load resistance of 400 Ω. An energy conversion efficiency of the device between rotational input energy and electrical output energy marks at 8.75%. The D-TENG and EMG are combined with a rotating waterwheel to demonstrate their ability to power an EC purification system. A power management integrated circuit (PMIC) is utilized with the D-TENG for high current input to the EC module. Finally, the W-HG successfully purifies wastewater with a high removal ratio above 95% for 18 h.

Mixed metal hydroxide (MMH) based supercapacitor electrodes, with their outstanding performance from the synergistic effect originating from mixed metallic elements, can effectively address the drawbacks of single metal hydroxide (SMH) based electrodes. Owing to their superior electrochemical properties stemming from their unique structural and chemical compositional design, MMH electroactive materials have attracted considerable attention for energy storage devices. Among those devices, a layered double hydroxide (LDH) structure has been emerged as an alternative electrode due to its large interlayer arrangement, high redox activity, and multiple oxidation states. Herein, we have successfully designed cobalt-iron LDH nanosheets (CoFe LDH NSs) on nickel fabric by a facile electrochemical deposition (ECD) method with a chronoamperometry voltage of − 1.0 V for 100 s. Further, the unique as-fabricated structure that arises from the tunable chemical composition and wide variety of material properties was successfully manipulated to boost the electrochemical energy storage performance. Finally, the optimized electrode made of Co0.5Fe0.5 exhibited superior electrochemical performance due to its porous, surface-stimulated large electroactive area and high conductivity with great stability. By integrating a battery-type electrode of CoFe LDH and a capacitive-type electrode of activated carbon (AC), a hybrid supercapacitor (HSC) device was assembled. Besides, the high areal capacitance of 70 µF/cm2, it delivers high energy density (1.6 mWh/cm2) and power density (0.09 mW/cm2) values along with the excellent cycling stability (91% capacity retention). Moreover, the fabricated flexible device offers the significance as a power source in flexible electronic devices with its high degree of flexibility originated from flexible substrate. This work not only provides a promising electrode for supercapacitors, but also a unique structural and compositional design of electroactive materials for energy storage systems.

With growing energy crisis in this era, developing and utilizing sustainable energy sources are required because the conventional energy sources cannot be restored. Among the various sustainable energy sources, the ocean wave energy is considered as one of the best sustainable energy sources. However, the conventional technologies to harvest the ocean energy show some limitations such as corrosion. Hence, guaranteeing the high resistance to corrosion of the harvesting devices has become a critical challenge for ocean-energy harvesting. Herein, a mat-shaped solid-liquid triboelectric nanogenerator is fabricated to harvest the blue energy while overcoming the shortcomings of the conventional technologies. The fabricated device is composed of the polydimethylsiloxane embedded in a conductive carbon black utilized as the electrode of the proposed device and it can directly harvest the blue energy. Moreover, through acquired energy from the simulated waves, the fabricated device can operate an anemometer and can split the seawater to produce the hydrogen. Also, the human motions can be distinguished through the k-mean clustering method with the high classification of 96.67%. Considering these results, the fabricated device is expected to be utilized as the promising blue energy harvester as well as the self-powered human motion sensor in near future.

Recently, flux-materials have attracted considerable attention for improving the photoluminescence (PL) properties of luminescent materials. Herein, the phase structure, morphology, PL property, thermal stability, and cathodoluminescence (CL) property of Ba2La0.9Eu0.1SbO6 phosphors with and without the flux-materials of NH4F, C6H8O7, and H3BO3 were investigated and compared. At first, these mentioned flux-materials would barely affect the crystal structure through analyzing the X-ray diffraction patterns and Rietveld refinements. However, the morphology, PL intensity, thermal stability, lifetime, and CL performance were implicated by adding the flux-materials. Especially, the C6H8O7 flux-material could obviously improve the emission intensity and CL property of Ba2La0.9Eu0.1SbO6 phosphors with respect to the other samples. In addition, these flux-materials could enhance thermal stability and lifetime. In terms of quantum yield, the H3BO3 flux-material has the best optimization capabilities. Briefly, this work would provide a deep insight into a kind of suitable flux-materials to optimize luminescent materials in the synthesized processes.

Combining the piezoelectric and triboelectric effects into a single device called hybrid nanogenerator (HNG) is a key discovery to overcome the drawback of low electrical output piezo/triboelectric nanogenerators. This work elaborates detailed electrical performance investigation on dopamine treated tin oxide (DA@SnO2) nanoparticles (NPs) impregnated polyvinylidene fluoride (PVDF)-based HNG. The mixing of SnO2 NPs inside the PVDF matrix enhances the β phase of the composite film and the electrical performance of the respective HNG. The coating of DA on SnO2 NPs works as a binder between SnO2 NPs and PVDF polymer by removing the defects in the SnO2/PVDF composite film. Also, the presence of carbon in DA increases electron generation inside the composite film, which further enhances the electrical output of HNG. With this effect, the fabricated DA@SnO2/PVDF-based HNG produced maximum electrical outputs of 62 V, 1.55 μA, and 17.9 μC/m2 which were considerably higher than those of the SnO2/PVDF-based HNG. Finally, the DA@SnO2/PVDF-based HNG was tested for different operational parameters and used to charge commercially available capacitors and power up small-scale electronics. The proposed HNG provides an excellent energy harvesting capability and can be employed to harvest energy from abundantly available mechanical movements.