Recently, aqueous
Zn-ion rechargeable batteries have drawn increasing
research attention as an alternative energy storage system relative
to the current Li-ion batteries due to their intrinsic properties
of high safety, low cost, and high theoretical volumetric capacity.
Nevertheless, unwanted dendrite growth on the Zn anode and unstable
cathode materials restrict their practical application. In this study,
a unique 2D MoS2 coating on a Zn anode using an electrochemical
deposition method has been developed for preventing dendrite growth
and intricate side reactions. The coated MoS2 layer is
a vertically oriented structure that makes the flow of Zn ions easy
with a uniform electric field distribution on the anode, resulting
in a uniform stripping and plating of Zn2+. In addition,
the MoS2 coating enhances anodic diffusion of Zn ions and
reduces the series resistance as confirmed by EIS analysis and therefore
improves the overall battery performance. The full cell assembled
with the MoS2–Zn anode and MnO2 cathode
exhibits an excellent reversible specific capacity of 638 mAh/g at
0.1 A/g and stable cycle performance over 2000 cycles with no dendrite
formation at the Zn electrode. The presented MoS2 coating
on Zn is a facile, scalable, and promising technology for practical
Zn-ion batteries with a long life cycle and high safety.
Alkaline electrolysis is one of the most promising among gas-to-power technologies to produce hydrogen energy where the oxygen evolution reaction (OER) plays an important role. It has recently been demonstrated that the OER activity of layered double hydroxide (LDH) could be enhanced by accommodating more abundant active sites that offer optimal binding energies between intermediates. Here, we report a study of nickel iron layered double hydroxides by varying the Ni:Fe atomic ratio of the Ni 1−x Fe x -LDH to induce changes to their physiochemical properties through which the optimum OER performance is determined. Optimized NiFe-LDH-38 (Ni 0.62 Fe 0.38 LDH) shows an excellent OER performance in alkaline electrolyte, demonstrating a potential of 1.45 V (vs RHE) at 100 mA cm −2 , which outperforms the commercial RuO 2 catalyst. Also, computational simulations support the OER performance of the single NiFe-LDH phase . This work provides not only a fundamental understanding of the effect of the Ni:Fe atomic ratio of the Ni 1−x Fe x -LDHs on OER performance but also the design strategy of lowcost, earth abundant, and active electrocatalysts toward water oxidation.
In this work, we prepared spinel-type NiCo2O4 (NCO) nanopowders as a low-cost and sensitive electrochemical sensor for nonenzymatic glucose detection. A facile and simple chemical bath method to synthesize the NCO nanopowders is demonstrated. The effect of pH and annealing temperature on the formation mechanism of NCO nanoparticles was systematically investigated. Our studies show that different pHs of the precursor solution during synthesis result in different intermediate phases and relating chemical reactions for the formation of NCO nanoparticles. Different morphologies of the NCO depending on pHs are also discussed based on the mechanism of growth. Electrochemical performance of the prepared NCO was characterized towards glucose, which reveals that sensitivity and selectivity of the NCO are significantly related with the final microstructure combined with constituent species with multiple oxidation states in the spinel structure.
Exploring bifunctional electrocatalysts to lower the activation energy barriers for sluggish electrochemical reactions for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great importance in achieving lower energy consumption and higher conversion efficiency for future energy conversion and storage system. Despite the excellent performance of precious metal-based electrocatalysts for OER and ORR, their high cost and scarcity hamper their large-scale industrial application. As alternatives to precious metal-based electrocatalysts, the development of earth-abundant and efficient catalysts with excellent electrocatalytic performance in both the OER and the ORR is urgently required. Herein, we report a core–shell CoFeS2@CoS2 heterostructure entangled with carbon nanotubes as an efficient bifunctional electrocatalyst for both the OER and the ORR. The CoFeS2@CoS2 nanocubes entangled with carbon nanotubes show superior electrochemical performance for both the OER and the ORR: a potential of 1.5 V (vs. RHE) at a current density of 10 mA cm−2 for the OER in alkaline medium and an onset potential of 0.976 V for the ORR. This work suggests a processing methodology for the development of the core–shell heterostructures with enhanced bifunctional performance for both the OER and the ORR.
We investigated the effect of specific surface area on the electrochemical properties of NiCo2O4 (NCO) for glucose detection. NCO nanomaterials with controlled specific surface areas were prepared by additive-assisted hydrothermal synthesis, and self-assembled nanostructures with urchin-, pine-needle-, tremella-, and flower-like morphologies were obtained. The novelty of this method is the systematic control of chemical reaction routes assisted by the addition of different additives during synthesis, which results in the spontaneous formation of various morphologies without any difference in the crystal structure and chemical states of the constituent elements. Such morphological control of NCO nanomaterials leads to considerable changes in the electrochemical performance for glucose detection. Combined with materials characterization, the relationship between the specific surface area and the electrochemical performance is discussed for glucose detection. This work can provide scientific insights for tailoring the surface area of nanostructures, which determines their functionality for potential applications in glucose biosensors.
We investigated the effect of specific surface area on the electrochemical properties of NiCo2O4 (NCO) for glucose detection. NCO nanomaterials with controlled specific surface areas were prepared by additive-assisted hydrothermal synthesis, and self-assembled nanostructures with urchin-, pine-needle-, tremella-, and flower-like morphologies were obtained. The novelty of this method is the systematic control of chemical reaction routes assisted by the addition of different additives during synthesis, which results in the spontaneous formation of various morphologies without any difference in the crystal structure and chemical states of the constituent elements. Such morphological control of NCO nanomaterials leads to considerable changes in the electrochemical performance for glucose detection. Combined with materials characterization, the relationship between the specific surface area and the electrochemical performance is discussed for glucose detection. This work can provide scientific insights for tailoring the surface area of nanostructures, which determines their functionality for potential applications in glucose biosensors.
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