ABSTRACT
In the present era of intelligent electronics and Internet of Things (IoT), the demand for flexible and wearable devices is very high. Here, we have developed a high-output flexible piezoelectric nanogenerator (PENG) based on electrospun poly(vinylidene fluoride) (PVDF)-barium titanate (BaTiO3) (ES PVDF-BT) composite nanofibers with an enhanced electroactive phase. On addition of 10 wt % BaTiO3 nanoparticles, the electroactive ß-phase of the PVDF is found to be escalated to â¼91% as a result of the synergistic interfacial interaction between the tetragonal BaTiO3 nanoparticles and the ferroelectric host polymer matrix on electrospinning. The fabricated PENG device delivered an open-circuit voltage of â¼50 V and short-circuit current density of â¼0.312 mA m-2. Also, the PVDF-BT nanofiber-based PENG device showed an output power density of â¼4.07 mW m-2, which is 10 times higher than that of a pristine PVDF nanofiber-based PENG device. Furthermore, the developed PENG has been newly demonstrated for self-powered real-time vibration sensing applications such as for mapping of mechanical vibrations from faulty CPU fans, hard disk drives, and electric sewing machines.
ABSTRACT
The CO2 adsorption properties of an organic macrocycle, cucurbit[6]uril (CB[6]), have been evaluated through experimental and theoretical studies. Quantum mechanical calculations show that CB[6] is capable of adsorbing the CO2 molecule selectively within its cavity relative to nitrogen. Adsorption experiments at 298 K and at 1 bar pressure gave a CO2 adsorption value of 1.23 mmol g-1 for the unmodified material. Significant enhancements in the CO2 adsorption capacity of the material were experimentally demonstrated through surface modification using physical and chemical methods. Ethanolamine (EA) modified CB[6] provided an excellent sorption selectivity value of 121.4 for CO2/N2 at 323 K and is unique with respect to its discrimination potential between CO2 and N2. The chemical nature of the interaction between CO2 and amine is shown to be the primary mechanism for the enhanced CO2 absorption performance.
ABSTRACT
Nitrogen containing mesoporous carbon obtained by the pyrolysis of graphene oxide (GO) wrapped ZIF-8 (Zeolitic Imidazolate Frameworks-8) micro crystals is demonstrated to be an efficient catalyst for the oxygen reduction reaction (ORR). ZIF-8 synthesis in the presence of GO sheets helped to realize layers of graphene oxide over ZIF-8 microcrystals and the sphere-like structures thus obtained, on heat treatment, transformed to highly porous carbon with a nitrogen content of about 6.12% and surface area of 502 m2/g. These catalysts with a typical micromeso porous architecture exhibited an onset potential of 0.88Vvs RHE in a four electron pathway and also demonstrated superior durability in alkaline medium compared to that of the commercial Pt/C catalyst. The N-doped porous carbon derived from GO sheathed ZIF-8 core-shell structures could therefore be employed as an efficient electrocatalyst for fuel cell applications.
