A Robust Triboelectric Impact Sensor with Carbon Dioxide Precursor-Based Calcium Carbonate Layer for Slap Match Application.

As an urgent international challenge, the sudden change in climate due to global warming needs to be addressed in the near future. This can be achieved through a reduction in fossil fuel utilization and through carbon sequestration, which reduces the concentration of CO2 in the atmosphere. In this study, a self-sustainable impact sensor is proposed through implementing a triboelectric nanogenerator with a CaCO3 contact layer fabricated via a CO2 absorption method. The triboelectric polarity of CaCO3 with the location between the polyimide and the paper and the effects of varying the crystal structure are investigated first. The impact sensing characteristics are then confirmed at various input frequencies and under applied forces. Further, the high mechanical strength and strong adherence of CaCO3 on the surface of the device are demonstrated through enhanced durability compared to the unmodified device. For the intended application, the as-fabricated sensor is used to detect the turning state of the paper Ddakji in a slap match game using a supervised learning algorithm based on a support vector machine presenting a high classification accuracy of 95.8%. The robust CaCO3-based triboelectric device can provide an eco-friendly advantage due to its self-powered characteristics for impact sensing and carbon sequestration.

FeV LDH Coated on Sandpaper as an Electrode Material for High-Performance Flexible Energy Storage Devices.

Recently, considerable research efforts to achieve advanced design of promising electroactive materials as well as unique structures in supercapacitor electrodes have been explored for high-performance energy storage systems. We suggest the development of novel electroactive materials with an enlarged surface area for sandpaper materials. Based on the inherent micro-structured morphologies of the sandpaper substrate, nano-structured Fe-V electroactive material can be coated on it by facile electrochemical deposition technique. A hierarchically designed electroactive surface is covered with FeV-layered double hydroxide (LDH) nano-flakes on Ni-sputtered sandpaper as a unique structural and compositional material. The successful growth of FeV-LDH is clearly revealed by surface analysis techniques. Further, electrochemical studies of the suggested electrodes are carried out to optimize the Fe-V composition as well as the grit number of the sandpaper substrate. Herein, optimized Fe0.75V0.25 LDHs coated on #15000 grit Ni-sputtered sandpaper are developed as advanced battery-type electrodes. Finally, along with the negative electrode of activated carbon and the FeV-LDH electrode, it is utilized for hybrid supercapacitor (HSC) assembly. The fabricated flexible HSC device indicates high energy and power density by showing excellent rate capability. This study is a remarkable approach to improving the electrochemical performance of energy storage devices using facile synthesis.

Development of MOF Based Recyclable Photocatalyst for the Removal of Different Organic Dye Pollutants.

The preparation of metal organic frameworks (MOFs) has come to the forefront in recent years because of their outstanding physical and chemical properties. Many MOFs such as Zn, Co, Ni, Fe, and Ag, etc., have been successfully synthesized. In this work, we followed the solvothermal assisted route to synthesize Ag-MOF (abbreviated as AMOF) nanosheets and then applied them as a photocatalyst to remove different organic pollutants, namely methyl orange (MO), crystal violet (CV), and methylene blue (MB). Chemical composition, optical properties, morphology, and microstructural analysis were analyzed using XPS, UV-visible spectrophotometer, FESEM, TEM, and EDS, respectively. The structural properties of AMOF nanosheets were studied by X-ray diffraction (XRD). Nitrogen adsorption and desorption isotherm analysis were utilized to evaluate the specific surface area and pore size of the AMOF nanosheets. Further, AMOF nanosheets showed notable photocatalytic performance for various dye pollutants degradation. The results confirmed 74.5, 85.5, and 90.7% of MO, CV, and MB dye pollutants removal after 120 min of irradiation with the rate constants (k) of 0.0123, 0.0153, and 0.0158 min-1, respectively. The effect of superoxide radicals (O2-) and photogenerated holes (h+) on the organic dye pollutants removal was investigated using radical scavenger trapping studies. Moreover, the stability study also confirmed the recyclability of the photocatalyst. Therefore, the findings of this research present a realizable method to grow AMOF photocatalyst for successful degradation of various dye pollutants.

Microwave-Assisted Hierarchically Grown Flake-like NiCo Layered Double Hydroxide Nanosheets on Transitioned Polystyrene towards Triboelectricity-Driven Self-Charging Hybrid Supercapacitors.

Recently, there is a need to explore the utilization of various heterostructures using the designed nanocomposites and tuning the surfaces of electrodes for improving the electrochemical performance of supercapacitors (SC). In this work, a novel approach is successfully employed through a facile two-step synthetic route with the assistance of a microwave for only 1 min. Depending on the glass transition of a polystyrene (PS) substrate and electrochemical deposition (ECD) of electroactive Ni-Co layered double hydroxides (LDHs), a hierarchically designed flake-like morphology can be readily prepared to enhance the surface-active sites, which allows a rhombohedral Ni-Co LDHs electrode to obtain superior electrochemical properties. Further, the interactions between electrode and electrolyte during the diffusion of ions are highly simplified using multiple enhanced electroactive sites and shorter pathways for electron transfer. The unique surface architecture of the PS substrate and the synergistic effect of the bimetallic components in Ni-Co LDHs enable this substrate to obtain desired electrochemical activity in charge storage systems. The optimized MWC Co0.5Ni0.5 electrode exhibited an areal capacity of 100 µAh/cm2 at a current density of 1 mA/cm2 and a remarkable capacity retention of 91.2% over 5000 continuous charging and discharging cycles due to its remarkable synergistic effect of abundant faradaic redox reaction kinetics. The HSC device is assembled with the combination of optimized MWC Co0.5Ni0.5 and activated carbon as a positive and negative electrode, respectively. Further, the electrochemical test results demonstrated that MWC Co0.5Ni0.5 //AC HSC device showed a high areal capacitance of 531.25 mF/cm2 at a current density of 5 mA/cm2. In addition, the fabricated an aqueous HSC device showed a power density of 16 mW/cm2 at an energy density of 0.058 mWh/cm2, along with the remarkable capacity retention of 82.8% even after 10,000 continuous charging and discharging cycles. Moreover, the assembled hybrid supercapacitor (HSC) device is integrated with a triboelectric nanogenerator (TENG) for the development of energy conversion and storage systems. Not only an extensive survey of materials but also an innovative solution for recent progress can confirm the wide range of potential SC applications. Remarkably, this study is a new way of constructing self-powered energy storage systems in the field of sustainable wearable electronics and future smart sensing systems.

Photocatalytic activity of MnTiO3 perovskite nanodiscs for the removal of organic pollutants.

MTO nanodiscs synthesized using the hydrothermal approach were explored for the photocatalytic removal of methylene blue (MB), rhodamine B (RhB), congo red (CR), and methyl orange (MO). The disc-like structures of ~16 nm thick and ~291 nm average diameter of stoichiometric MTO were rhombohedral in nature. The MTO nanodiscs delivered stable and recyclable photocatalytic activity under Xe lamp irradiation. The kinetic studies showed the 89.7, 80.4, 79.4, and 79.4 % degradation of MB, RhB, MO, and CR at the rate constants of 0.011(±0.001), 0.006(±0.001), 0.007(±0.0007), and 0.009 (±0.0001) min-1, respectively, after the 180 min of irradiation. The substantial function of photogenerated holes and hydroxide radicals pertaining to the dye removal phenomena is confirmed by radical scavenger trapping studies. Overall, the present studies provide a way to develop pristine and heterostructure perovskite for photocatalysts degradation of various organic wastes.

Structural correlation of a nanoparticle-embedded mesoporous CoTiO3 perovskite for an efficient electrochemical supercapacitor.

We synthesized mesoporous cobalt titanate (CTO) microrods via the sol-gel method as an outstanding working electrode for the supercapacitor. The mesoporous CTO microrods were amassed in hexagonal shapes of an average width of ∼670 nm, and were composed of nanoparticles of average diameter ∼41 nm. The well crystalline CTO microrods of the hexagonal phase to the R3̄ space group possessed an average pore size distribution of 3.92 nm throughout the microrod. The mesoporous CTO microrods with increased textural boundaries played a vital role in the diffusion of ions, and they provided a specific capacitance of 608.4 F g-1 and a specific power of 4835.7 W kg-1 and a specific energy of 9.77 W h kg-1 in an aqueous 2 M KOH electrolyte, which was remarkably better than those of Ti, La, Cr, Fe, Ni, and Sr-based perovskites or their mixed heterostructures supplemented by metal oxides as an impurity. Furthermore, the diffusion-controlled access to the OH- ions (0.27 µs) deep inside the microrod conveyed high stability, a long life cycle for up to 1950 continuous charging-discharging cycles, and excellent capacitance retention of 82.3%. Overall, the mesoporous CTO shows its potential as an electrode for a long-cycle supercapacitor, and provides opportunities for additional enhancement after developing the core-shell hetero-architecture with other metal oxide materials such as MnO2, and TiO2.