The unique properties of aqueous polyoxometalate (POM) mixtures and their role in the design of molecular coatings for electrochemical energy storage

Genovese, Matthew; Foong, Yee Wei; Lian, Keryn

doi:10.1016/j.electacta.2016.01.145

Cited by 36 publications

(12 citation statements)

References 42 publications

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“…Rather, a substantial increase in the first reduction peak potential of ∼600 mV was observed for the Mo 1 W 11 anion compared to W 12 POM, in which a W 6+ was substituted by Mo 6+ . The substantial change induced in the first redox potential is associated with the fact that the electron added to the mixed-addenda POM anion in the reduction step is localized on the Mo center because Mo 6+ in a fully oxidized POM has a greater electron affinity than W 6+ . − Indeed, in both Mo 12 POM and W 12 POM, all of the metal centers have an equal probability to accept additional electrons during reduction. However, when a W 6+ is replaced by a Mo 6+ as in MoW 11 POM, the additional electron has a higher probability of going to the Mo-centered orbital.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Based on this previous work, it is plausible that specific mixed-addenda molybdenum–tungsten POM anions ( i.e. , PMo x W 12– x O 40 ) may offer the combined advantages of both higher redox activity and stability. − We hypothesized that investigation of atom-by-atom substitution of molybdenum with tungsten in the PMo 12 O 40 3– anion may identify a more-stable and more-reactive mixed-addenda POM, which will be beneficial for the development of high-performance and stable energy-storage devices.…”

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confidence: 99%

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Controlling the Activity and Stability of Electrochemical Interfaces Using Atom-by-Atom Metal Substitution of Redox Species

et al. 2018

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Understanding the molecular-level properties of electrochemically active ions at operating electrode–electrolyte interfaces (EEI) is key to the rational development of high-performance nanostructured surfaces for applications in energy technology. Herein, an electrochemical cell coupled with ion soft landing is employed to examine the effect of “atom-by-atom” metal substitution on the activity and stability of well-defined redox-active anions, PMo x W12–x O40 3– (x = 0, 1, 2, 3, 6, 9, or 12) at nanostructured ionic liquid EEI. A striking observation made by in situ electrochemical measurements and further supported by theoretical calculations is that the substitution of only one to three tungsten atoms by molybdenum atoms in the PW12O40 3– anions results in a substantial spike in their first reduction potential. Specifically, PMo3W9O40 3– showed the highest redox activity in both in situ electrochemical measurements and as part of a functional redox supercapacitor device, making it a “super-active redox anion” compared with all other PMo x W12–x O40 3– species. Electronic structure calculations showed that metal substitution in PMo x W12–x O40 3– causes the lowest unoccupied molecular orbital (LUMO) to protrude locally, making it the “active site” for reduction of the anion. Several critical factors contribute to the observed trend in redox activity including (i) multiple isomeric structures populated at room temperature, which affect the experimentally determined reduction potential; (ii) substantial decrease of the LUMO energy upon replacement of W atoms with more-electronegative Mo atoms; and (iii) structural relaxation of the reduced species produced after the first reduction step. Our results illustrate a path to achieving superior performance of technologically relevant EEIs in functional nanoscale devices through understanding of the molecular-level electronic properties of specific electroactive species with “atom-by-atom” precision.

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Section: Results and Discussionmentioning

confidence: 99%

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confidence: 99%

Controlling the Activity and Stability of Electrochemical Interfaces Using Atom-by-Atom Metal Substitution of Redox Species

et al. 2018

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“…[42,43] At the same time, W ion from the hydrolysis of part of POMs doped into the lattice of LDH. [44] Then, the formed LDH nanosheets aggregated together and assembled to 3D micro-flower-like structure.…”

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In Situ Growth of 3D NiFe LDH‐POM Micro‐Flowers on Nickel Foam for Overall Water Splitting

Zhang

2020

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Considering the intermittency of typical renewable and environment-friendly energy resources, such as wind, tide, and solar energy, it is encouraging to explore all-weather utilization ones. [1] Electrochemical water splitting for hydrogen and oxygen production may overcome the challenge as an ideal sustainable system for the future. [2] Unfortunately, the high activation barriers and sluggish kinetics of hydrogen and oxygen evolution reactions (HER and OER) hindered their further applications. [3] Since HER and OER must be operated in the same electrolyte for overall water splitting, efficient bifunctional electrocatalysts, which can prevent cross-contamination, materials incompatibilities, and possible catalyst poisoning, are attracting everincreasing attentions. [4] Earth-abundant transition metal layered double hydroxides (LDHs) have been recognized as promising electrocatalysts

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“…296,297 For example, PMo 12 O 40 3− on nanocarbon provides pseudocapacitive current. 298 Polyaniline/ PMo 12 and PEDOT/PMo 12 composites are fabricated to form supercapacitor electrode, 299 whereas polyoxomolybdate hybrids strongly interact with reduced graphene oxide and the resulting hybrids present good hydrogen peroxide reduction and large capacitance. 300 301 Copyright ACS (2016) 301 [Colour figure can be viewed at wileyonlinelibrary.com] present better polyoxometalate loading, which is promising for capacitor application (Figure 9).…”

Section: Polyoxotungstatementioning

confidence: 99%

“…Polyoxomolybdates have been applied to supercapacitors . For example, PMo 12 O 40 3− on nanocarbon provides pseudocapacitive current . Polyaniline/PMo 12 and PEDOT/PMo 12 composites are fabricated to form supercapacitor electrode, whereas polyoxomolybdate hybrids strongly interact with reduced graphene oxide and the resulting hybrids present good hydrogen peroxide reduction and large capacitance .…”

Section: Polyoxomolybdatementioning

confidence: 99%

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

Zhang

Chen

2020

Int J Energy Res

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Summary Polyoxometalates could be viewed as the molecular counterpart of the metal oxides, which are essential ingredients for various energy conversion and storage applications. In this manuscript, we review the progress of engineering functional polyoxometalates toward energy applications, focusing on, but not limited to, polyoxotitanate, polyoxotungstate, and polyoxomolybdate. These polyoxometalates are considered to be promising candidates for dye‐sensitized solar cell, perovskite solar cell, lithium‐ion battery, lithium‐sulfur battery, supercapacitor, and water‐splitting system. We believe advanced energy devices with better performance could be derived from further engineering the polyoxometalates owing to their molecular design flexibility.

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The unique properties of aqueous polyoxometalate (POM) mixtures and their role in the design of molecular coatings for electrochemical energy storage

Cited by 36 publications

References 42 publications

Controlling the Activity and Stability of Electrochemical Interfaces Using Atom-by-Atom Metal Substitution of Redox Species

Controlling the Activity and Stability of Electrochemical Interfaces Using Atom-by-Atom Metal Substitution of Redox Species

In Situ Growth of 3D NiFe LDH‐POM Micro‐Flowers on Nickel Foam for Overall Water Splitting

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

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