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  1. Abstract

    Ionic liquids (ILs) are promising electrolytes for high‐performance Li‐ion batteries (LIBs), which can significantly improve the safety and energy storage capacity. Although extensive experimental and computational studies have reported, further exploration is needed to understand the properties of IL systems, their microscopic structures and dynamics, and the behavior of Li ions in ILs. We report here results of molecular dynamics simulations as a function of electric field for Li diffusion in two IL systems, [EMIM][TFSI] and [BMIM][TFSI] doped with various concentrations of LiTFSI. We find that the migration of each individual Li ion depends largely on its micro‐environment, leading to differences by factors of up to 100 in the diffusivity. The structural and dynamical properties indicate that Li diffusion is affected significantly by the coordination and interaction with the oxygen species in the TFSI anions. Moreover, the IL cations also contribute to the Li diffusion mechanism by attenuating the Li–TFSI interaction.

     
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  2. Abstract

    Motivated by in silico predictions that Co, Rh, and Ir dopants would lead to low overpotentials to improve OER activity of Ni‐based hydroxides, we report here an experimental confirmation on the altered OER activities for a series of metals (Mo, W, Fe, Ru, Co, Rh, Ir) doped into γ‐NiOOH. The in situ electrical conductivity for metal doped γ‐NiOOH correlates well with the trend in enhanced OER activities. Density functional theory (DFT) calculations were used to rationalize the in situ conductivity of the key intermediate states of metal doped γ‐NiOOH during OER. The simultaneous increase of OER activity with intermediate conductivity was later rationalized by their intrinsic connections to the double exchange (DE) interaction between adjacent metal ions with variousdorbital occupancies, serving as an indicator for the key metal‐oxo radical character, and an effective descriptor for the mechanistic evaluation and theoretical guidance in design and screening of efficient OER catalysts.

     
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  3. Abstract

    Harnessing renewable electricity to drive the electrochemical reduction of CO2is being intensely studied for sustainable fuel production and as a means for energy storage. Copper is the only monometallic electrocatalyst capable of converting CO2to value-added products, e.g., hydrocarbons and oxygenates, but suffers from poor selectivity and mediocre activity. Multiple oxidative treatments have shown improvements in the performance of copper catalysts. However, the fundamental underpinning for such enhancement remains controversial. Here, we combine reactivity, in-situ surface-enhanced Raman spectroscopy, and computational investigations to demonstrate that the presence of surface hydroxyl species by co-electrolysis of CO2with low concentrations of O2can dramatically enhance the activity of copper catalyzed CO2electroreduction. Our results indicate that co-electrolysis of CO2with an oxidant is a promising strategy to introduce catalytically active species in electrocatalysis.

     
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  4. Free, publicly-accessible full text available April 1, 2024
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