High surface area provides abundant active sites for catalytic reaction High Surface area Open crystal structure can exposes more interior atoms to provide more active sites Open crystal structure Organic linker acts as source of nitrogen source to improve the conductivity of overall matrix Organic linker Metal nanoparticles and metal complexes can be encapsulated inside MOFs to form guest@MOFs Tunable pore structure Figure 2.Advantages of the ZIF-67 for electrocatalytic application. The schematics of ZIF-67 was reproduced under the terms of the CC BY license. [468]

To fulfill the high power and high energy density demands for Li-ion batteries (LIBs) new anode materials need to be explored to replace conventional graphite. Herein, we report the urea assisted facile co-precipitation synthesis of spinel NiCo2O4 and its application as an anode material for LIBs. The synthesized NiCo2O4 exhibited an urchin-like microstructure and polycrystalline and mesoporous nature. In addition, the mesoporous NiCo2O4 electrode exhibited an initial discharge capacity of 1095 mA h g(-1) and maintained a reversible capacity of 1000 mA h g(-1) for 400 cycles at 0.5 C-rate. The reversible capacity of NiCo2O4 could still be maintained at 718 mA h g(-1), even at 10 C. The mesoporous NiCo2O4 exhibits great potential as an anode material for LIBs with the advantages of unique performance and facile preparation.

The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of monitoring the environment to prevent hazard to humans has sparked research on binary metal oxides. Here we report on a novel ozone gas sensor made with ca. 0.5 m yolk-shelled ZnCo 2 O 4 microstructures synthesized via an eco-friendly, co-precipitation method and subsequent annealing. With these ZnCo 2 O 4 microspheres, ozone concentrations down to 80 parts per billion (ppb) could be detected with a.c. and d.c. electrical measurements. The sensor worked within a wide range of ozone concentrations, from 80 to 890 ppb, being also selective to ozone compared to CO, NH 3 and NO 2. The high performance could be attributed to the large surface area to volume ratio inherent in yolk-shell structures. Indeed, ozone molecules adsorbed on the ZnCo 2 O 4 surface create a layer of holes that affect the conductivity, as in a p-type semiconductor. Since this mechanism of detection is generic, ZnCo 2 O 4 microspheres can be further used in other environment monitoring devices.

Copper oxide (CuO) thin films are successfully synthesized using a surfactant assisted chemical bath deposition method for application in supercapacitors. The effect of organic surfactants such as Triton X-100 and polyvinyl alcohol (PVA) on structural, morphological, surface areas and electrochemical properties of CuO thin films is investigated. The films deposited using organic surfactants exhibit different surface morphologies. It is observed that the organic surfactants play important roles in modifying the morphology, surface area and pore size distribution. Electrochemical analysis confirms that the nanostructures of the electrode material play a vital role in supercapacitors. The cyclic voltammetry studies show a considerably improved high rate pseudocapacitance of CuO samples synthesized using organic surfactants. The maximum specific capacitance of 411 F g(-1) at 5 mV s(-1) is obtained for the CuO sample prepared using an organic surfactant (Triton X-100). Furthermore, all the CuO nanostructures exhibit high power performance, excellent rate as well as long term cycling stability. The Ragone plot ascertains better power and energy densities of CuO nanostructured samples. This is an easy and simple way to tune the morphology using surfactants which can be applied for other energy storage materials.

A room-temperature synthesized NiFeCe2 electrocatalyst delivered a current density of 10 mA cm−2 at a cell voltage of 1.59 V when used as the electrolyzer.

Ternary spinel CuCo2O4 nanostructure clenches great potential as high-performance electrode material for next-generation energy storage systems because of its higher electrical conductivity and electrochemical activity. Carbon free and binder free 3D flower-like CuCo2O4 structure are grown on nickel foam (NF) via a facile hydrothermal synthesis method followed by annealing. The obtained CuCo2O4/NF is directly used as electrode for lithium ion batteries (LIBs) and supercapacitors (SCs) application. The electrochemical study of 3D flower-like CuCo2O4 as an electrode for LIB and SC shows highly mesoporous unique architecture plays important role in achieving high capacity/capacitance with superior cycle life. The high surface area and mesoporous nature not only offer sufficient reaction sites, but also can accelerate the liquid electrolyte to penetrate electrode and the ions to reach the reacting sites. In outcome, it exhibits highest capacity of 1160 mA h g−1 after 200 cycles when used as an anode for LIB and specific capacitance of 1002 F g−1 after 3000 cycles. The superior electrochemical of synthesized material is attributed to direct contact of electrode active material with good intrinsic electrical conductivity to the underneath conductive NF substrate builds up an express path for fast ion and electron transfer.

In this study, the deep eutectic solvent (DES)-aided synthesis of γ-CoV 2 O 6 under modest reaction conditions using 1:1 choline chloride−malonic acid was reported. In the presence of DES, the reaction occurred at a lower temperature (500 °C) compared with that of the respective conventional solid-state synthesis of metal oxides and also with the calcination process involving the metal salts, thereby decreasing the overall formation energy. Differential scanning calorimetry revealed a 2-fold decrease in the endo effect of the thermodestruction of DES, which was observed at a low temperature. The structural pathway taken during the phase and morphology formation was investigated by in situ and ex situ X-ray diffraction (XRD) analysis, Raman spectroscopy, and scanning electron microscopy. The in situ XRD results confirmed the presence of high-temperature α-CoV 2 O 6 , which was finally converted to γ-CoV 2 O 6 . On account of the metal speciation in DES similar to the biotemplate, well-defined octahedral CoV 2 O 6 nanocrystals were obtained, which exhibited a remarkable OER catalytic activity at current density of 10 mA/cm 2 with an overpotential of a mere 324 mV, with excellent durability for greater than 24 h. Thus, a designer DES solvent with characteristics of biodegradability, cost-effectiveness, and renewability demonstrates potential for the synthesis of noble-metal-free oxygen evolution reaction (OER) catalysts, which allows the present synthesis route to fit well within the merits of green chemistry.

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