Strong intramolecular charge-transfer effect strengthening naphthoquinone-based chemosensor: Experimental and theoretical evaluation.

An aminophenol-linked naphthoquinone-based fluorometric and colorimetric chemosensor 2-chloro-3-((3-hydroxyphenyl) amino) naphthalene-1,4-dione (2CAN-Dione) was synthesized for selective detection of Sn2+ ion in aqueous solution. The amine and conversion of carbonyl into carboxyl groups play a vital role in the sensing mechanism when Sn2+ is added to 2CAN-Dione. Comprehensive characterization of the sensor was carried out using standard spectral and analytical approaches. Because of the intramolecular charge transfer (ICT) effect and the turn-on sensing mode, the strong fluorometric emission towards Sn2+ was observed at about 435 nm. The chemosensor exhibited good selectivity for Sn2+ in the presence of coexisting metal ions. An improved linear connection was established with a low limit of detection (0.167 µM). FT-IR, 1H NMR, 13C NMR, and quantum chemistry methods were performed to verify the binding coordination mechanism. The chemosensing probe 2CAN-Dione was successfully employed in bioimaging investigations, demonstrating that it is a reliable fluorescent marker for Sn2+ in human cancer cells.

Trimetallic Oxide Electrocatalyst for Enhanced Redox Activity in Zinc-Air Batteries Evaluated by In Situ Analysis.

Researchers are investigating innovative composite materials for renewable energy and energy storage systems. The major goals of this studies are i) to develop a low-cost and stable trimetallic oxide catalyst and ii) to change the electrical environment of the active sites through site-selective Mo substitution. The effect of Mo on NiCoMoO4 is elucidated using both in situ X-ray absorption spectroscopy and X-ray diffraction analysis. Also, density functional theory strategies show that NiCoMoO4 has extraordinary catalytic redox activity because of the high adsorption energy of the Mo atom on the active crystal plane. Further, it is demonstrated that hierarchical nanoflower structures of NiCoMoO4 on reduced graphene oxide can be employed as a powerful bifunctional electrocatalyst for oxygen reduction/evolution reactions in alkaline solutions, providing a small overpotential difference of 0.75 V. Also, Zn-air batteries based on the developed bifunctional electrocatalyst exhibit outstanding cycling stability and a high-power density of 125.1 mW cm-2 . This work encourages the use of Zn-air batteries in practical applications and provides an interesting concept for designing a bifunctional electrocatalyst.

Developing Outstanding Bifunctional Electrocatalysts for Rechargeable Zn-Air Batteries Using High-Purity Spinel-Type ZnCo2 Se4 Nanoparticles.

Zinc-air batteries are gaining popularity as viable energy sources for green energy storage technologies. The cost and performance of Zn-air batteries are mostly determined by the air electrodes in combination with an oxygen electrocatalyst. This research aims at the particular innovations and challenges relating to air electrodes and related materials. Here, a nanocomposite of ZnCo2 Se4 @rGO that exhibits excellent electrocatalytic activity for the oxygen reduction reaction, ORR (E1/2  = 0.802 V), and oxygen evolution reaction, OER (η10  = 298 mV@10 mA cm-2 ) is synthesized. In addition, a rechargeable zinc-air battery with ZnCo2 Se4 @rGO as the cathode showed a high open circuit voltage (OCV) of 1.38 V, a peak power density of 210.4 mW cm-2 , and outstanding long-term cycling stability. The electronic structure and oxygen reduction/evolution reaction mechanism of the catalysts ZnCo2 Se4 and Co3 Se4 are further investigated using density functional theory calculations. Finally, a perspective for designing, preparing, and assembling air electrodes is suggested for the future developments of high-performance Zn-air batteries.

Quasihexagonal Platinum Nanodendrites Decorated over CoS2 -N-Doped Reduced Graphene Oxide for Electro-Oxidation of C1-, C2-, and C3-Type Alcohols.

The development of efficient and highly durable materials for renewable energy conversion devices is crucial to the future of clean energy demand. Herein, cage-like quasihexagonal structured platinum nanodendrites decorated over the transition metal chalcogenide core (CoS2 )-N-doped graphene oxide (PtNDs@CoS2 -NrGO) through optimized shape engineering and structural control technology are fabricated. The prepared electrocatalyst of PtNDs@CoS2 -NrGO is effectively used as anodic catalyst for alcohol oxidation in direct liquid alcohol fuel cells. Notably, the prepared PtNDs@CoS2 -NrGO exhibits superior electrocatalytic performance toward alcohol oxidation with higher oxidation peak current densities of 491.31, 440.25, and 438.12 mA mgpt -1 for (methanol) C1, (ethylene glycol) C2, and (glycerol) C3 fuel electrolytes, respectively, as compared to state-of-the-art Pt-C in acidic medium. The electro-oxidation durability of PtNDs@CoS2 -NrGO is investigated through cyclic voltammetry and chronoamperometry tests, which demonstrate excellent stability of the electrocatalyst toward various alcohols. Furthermore, the surface and adsorption energies of PtNDs and CoS2 are calculated using density functional theory along with the detailed bonding analysis. Overall, the obtained results emphasize the advances in effective precious material utilization and fabricating techniques of active electrocatalysts for direct alcohol oxidation fuel cell applications.