A Mild Rhodium Catalyzed Direct Synthesis of Quinolones from Pyridones: Application in the Detection of Nitroaromatics.

A rhodium catalyzed direct regioselective oxidative annulation by double C-H activation is described to synthesize highly substituted quinolones from pyridones. The reaction proceeds at mild conditions with broad scope and wide functional group tolerance. These novel quinolones were explored to recognize nitroaromatic compounds.

In situ-grown organo-lead bromide perovskite-induced electroactive γ-phase in aerogel PVDF films: an efficient photoactive material for piezoelectric energy harvesting and photodetector applications.

The unique combination of piezoelectric energy harvesters and light detectors progressively strengthens their application in the development of modern electronics. Here, for the first time, we fabricated a polyvinylidene fluoride (PVDF) and formamidinium lead bromide nanoparticle (FAPbBr3 NP)-based composite aerogel film (FAPbBr3/PVDF) for harvesting electrical energy and photodetector applications. The uniform distribution of FAPbBr3 NPs in FAPbBr3/PVDF was achieved via the in situ synthesis of FAPbBr3 NPs in the PVDF matrix, which led to the stabilization of the γ-phase. The freeze-drying process induced an interconnected porous architecture in the composite film, making it more sensitive to small mechanical stimuli. Owing to this unique fabrication technique, the constructed aerogel film-based nanogenerator (FPNG) exhibited an output voltage and current of ∼26.2 V and ∼2.1 µA, respectively, which were 5-fold higher than that of the nanogenerator with the pure PVDF film. Also, the sensitivity of FPNG upon the irradiation of light was demonstrated by the output voltage reduction of ∼38%, indicating its capability as a light sensing device. Furthermore, the prepared FAPbBr3/PVDF composite was found to be an efficient candidate for light detection applications. A simple planar photodetector was fabricated with the 8.0 wt% FAPbBr3 NP-loaded PVDF composite, which displayed very high responsivity (8 A/W) and response speed of 2.6 s. Thus, this exclusive combination of synthesis and fabrication for the preparation of electro-active films opens a new horizon in the piezoelectric community for effective energy harvesting and light detector applications.

Triboelectric Nanogenerator Driven Self-Charging and Self-Healing Flexible Asymmetric Supercapacitor Power Cell for Direct Power Generation.

The expeditious growth of portable electronics has endorsed the researchers to develop self-powered devices that synchronically harvest and store energy. However, it is quite challenging to integrate two distinct phenomena in a single portable device. Here, we emphasize the fabrication of a triboelectric driven self-charging and self-healing asymmetric supercapacitor (SCSHASC) power cell composed of magnetic cobalt ferrite grown on a stainless steel (SS) fabric (CoFe2O4@SS) as positive and iron oxides decorated reduced graphene oxide grown on a SS fabric (Fe-RGO@SS) as negative electrodes separated by a KOH-soaked self-healing polymer hydrogel electrolyte membrane. The membrane contains Fe3+ cross-linked polyacrylic acid, whereas self-healing carboxylated polyurethane was utilized for encapsulation. SS fabric and poly(vinylidene fluoride- co-hexafluoropropylene) (PVDF-HFP)/SS-impregnated micropatterned PDMS composite film-strip were employed as positive and negative triboelectric friction layers, respectively. During mechanical deformation, the SCSHASC harvests electrical energy and subsequently stores it as electrochemical energy for sustainable power supply. The sandwich-type SCSHASC power cell (a supercapacitor unit sandwiched between two parallelly connected high-performance triboelectric nanogenerators) was charged up to ∼1.6 V within ∼31 min under periodic compression/stress ( F ≈ 17.6 N, f ≈ 3.80 Hz). Furthermore, the SCSHASC# (with two supercapacitor units in series) can instantly power-up several portable electronic appliances on periodic compression and release. Thus, the SCSHASC with unique design will be extremely beneficial for self-powered electronics.

Morphological interference of two different cobalt oxides derived from a hydrothermal protocol and a single two-dimensional metal organic framework precursor to stabilize the ß-phase of PVDF for flexible piezoelectric nanogenerators.

Here, we have fabricated a piezoelectric nanogenerator (PENG) composed of a Co-oxide (Co3O4) doped electro active PVDF based nanocomposite for efficient piezoelectric energy harvesting application where the Co3O4 inclusion favours nucleation and polar ß-phase stabilization in the nanocomposite. The morphological effect on the nucleation and ß-phase stabilisation of PVDF has been explored experimentally. The flake-like morphology of Co3O4 nanoparticles, synthesized by using a MOF, has a more effective surface area to nucleate and stabilise the ß-phase of PVDF than that of rod-like (hydrothermal) and spherical (commercial) nanoparticles. The PENG with PVDF and the 1.5 wt% MOF based Co3O4 (MPNG) shows an excellent open circuit voltage (∼37 V) and short circuit current (∼0.711 µA) upon human finger tapping. The maximum power density generated from the MPNG is ∼8.55 µW cm-2, which is well sufficient for the driving of portable electronic devices like LEDs, calculator wrist watches, humidity sensors etc. Also, from various easily accessible mechanical and biomechanical energy sources like heel pressing, walking, and machine vibration, the MPNG is capable of harvesting energy.