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Room temperature ionic liquids （ILs） composed of cations and anions, as well as deep eutectic solvents （DESs） composed of hydrogen bond donors （HBDs） and hydrogen bond acceptors （HBAs）, are regarded as green solvents due to their low volatility. They have been used widely for electrochemically driven reactions because they exhibit high conductivity and excellent elec- trochemical stability. However, no systematic investigations on the electrochemical potential windows （EPWs）, which could be used to characterize the electrochemical stability, have been reported. In this regard, the EPWs of 33 ILs and 23 DESs have been studied utilizing cyclic voltammetry （CV） method and the effects of structural factors （cations and anions of ILs, and HBDs and HBAs of DESs） and external factors （electrode, water content） on the EPWs have been comprehensively investi- gated. The electrochemical stability of selected 1Ls comprising five traditional cations, namely imidazolium, pyridinium, pyr- rolidinium, piperidinium and ammonium and 13 kinds of versatile anions was studied. The results show that for ILs, both cati- on and anion play an important role on the reductive and oxidative potential limit. For a same IL at different working electrode, for example, glassy carbon （GC）, gold （Au） and platinum （Pt） electrode, the largest potential window is almost observed on the GC working electrode. The investigations on the EPWs of choline chloride （ChCl）, choline bromide （ChBr）, choline iodide （ChI）, and methyl urea based DESs show that the DES composed of ChCl and methyl urea has the largest potential window. This work may aid the selection of ILs or DESs for use as a direct electrolyte or a solvent in electrochemical applications.

Using density functional theory （DFT） calculations, we rationally designed metallic nanocatalysts with ternary transition metals for oxygen reduction reactions （ORRs） in fuel cell applications. We surrounded binary core-shell nanoparticles with a Pt skin layer. To overcome surface segregation of the core 3-d transition metal, we identified the binary alloy Cu0.76Ni0.24 as having strongly attractive atomic interactions by computationally screening 158 different alloy configurations using energy convex hull theory. The PtskinCu0.76Ni0.24 nanoparticle showed better electrochemical stability than pure Pt nanoparticles -3 nm in size. We propose that the underlying mechanism originates from favorable compressive strain on Pt for ORR catalysis and atomic interactions among the nanoparticle shells for electrochemical stability. Our results will contribute to accurate identification and innovative design of promising nanomaterials for renewable energy systems.

On-chip microsupercapacitors （MSCs） compatible with on-chip geometries of integrated circuits can be used either as a separate power supply in microelectronic devices or as an energy storage or energy receptor accessory unit. In this work, we report the fabrication of flexible two-dimensional Ni（OH）2 nanoplates-based MSCs, which achieved a specific capacitance of 8.80 F/cm^3 at the scan rates of 100 mV/s, losing only 0.20% of its original value after 10,000 charge/discharge cycles. Besides, the MSCs reached an energy density of 0.59 mWh/cm^3 and a power density up to 1.80 W/cm^3, which is comparable to traditional carbon-based devices. The flexible MSCs exhibited good electrochemical stability when subjected to bending at various conditions, illustrating the promising application as electrodes for wearable energy storage.

Developing electrolyte with high electrochemical stability is the most effective way to improve the energy density of double layer capacitors （DLCs）, and ionic liquid is a promising choice. Herein, a novel ionic liquid based high potential electrolyte with a stabilizer, succinonitrile, was proposed to improve the high potential stability of the DLC. The electrolyte with 7.5 wt% succinonitrile added has a high ionic conductivity of 41.1 mS cm-1 under ambient temperature, and the DLC adopting this electrolyte could be charged to 3.0 V with stable cycle ability even under a discharge current density of 6 A g-1. Moreover, the energy density could be increased by 23.4% when the DLC was charged to 3.0 V compared to that charged to 2.7 V.

A room temperature ionic liquid crystal, 1-dodecyl-3-ethylimidazolium iodide （C12EImI）, and an ionic liquid, 1-decyl-3- ethylimidazolium iodide （Cl0EImI）, have been synthesized, characterized and employed as the electrolyte for dye-sensitized solar cells （DSSC）. The physicochemical properties show that a smectic A （SmA） phase with a lamellar structure is formed in CIzEImI. Both C~2EImI and Cl0EImI have good electrochemical and thermal stability facilitating their use in DSSC. The steady-state voltammograms reveal that the diffusion coefficient of I3- in C~2EImI is larger than that in CmEImI, which is at- tributed to the existence of the SmA phase in Ca2EImI. Because the iodide species are located between the layers of imidazo- lium cations in CjzEImI, exchange reaction-based diffusion is increased with a consequent increase in, the overall diffusion. The electrochemical impedance spectrum reveals that charge recombination at the dyed TiOJelectrolyte interface of a C12EImI-based DSSC is reduced due to the increase in I3- diffusion, resulting in higher open-circuit voltage. Moreover, both short-circuit current density and fill factor of the Cl2EImI based DSSC increase, as a result of the increasing transport of I3 in C~2EImI. Consequently, the photoelectric conversion efficiency of C~2EImI-based DSSC is higher than that of the Cl0EImI-based DSSC.

The enhanced electrochemical stability of the synthesized hybrid catalyst has been demonstrated by the introduction of the synergistic effect between carbon powder additive and the prepared catalyst.Single crystal IrO 2 nanorod （SC-IrO 2 NR） catalyst was prepared by a sol-gel method.The structure and performance of the catalyst sample were characterized by X-ray diffraction spectroscopy （XRD）,scanning electron microscope （SEM）,transmission electron microscope （TEM）,rotating disk electrode （RDE） and cyclic voltammetry （CV） measurements.XRD patterns and TEM images indicate that the catalyst sample has a rutile IrO 2 single crystal nanorod structure.The onset potential for oxygen reduction reaction （ORR） of the SC-IrO 2 NR-carbon hybrid catalyst specimen is 0.75 V （vs.RHE） in RDE measurement.CV and RDE test results show that the SC-IrO 2 NR-carbon hybrid catalyst has a better electrochemical stability in comparison with the commercial Pt/C catalyst,with attenuation ratios of 17.67% and 44.60% for the SC-IrO 2 NR-carbon hybrid catalyst and the commercial Pt/C catalyst after 1500 cycles,respectively.Therefore,in terms of stability,the SC-IrO 2 NR-carbon hybrid catalyst has a promising potential in the application of the proton exchange membrane fuel cell.