Jamie M. Cameron

Asymmetric functionalisation of polyoxometalates with tailored functionality yields stimuli-responsive, redox-active molecules that can form soft assemblies or graft onto nano- and macroscale surfaces.

An organofunctionalised hybrid polyoxometalate bearing Ru antennae exhibits selective CO₂ electrochemical reduction to C1 feedstocks.

Herein, we report the synthesis and characterization of a new class of hybrid Wells–Dawson polyoxometalate (POM) containing a diphosphoryl group (P₂O₆X) of the general formula [P₂W₁₇O₅₇(P₂O₆X)]⁶⁻(X=O, NH, or CR¹R²). Modifying the bridging unit X was found to impact the redox potentials of the POM. The ease with which a range of α‐functionalized diphosphonic acids (X=CR¹R²) can be prepared provides possibilities to access diverse functionalized hybrid POMs. Compared to existing phosphonate hybrid Wells–Dawson POMs, diphosphoryl‐substituted POMs offer a wider tunable redox window and enhanced hydrolytic stability. This study provides a basis for the rational design and synthesis of next‐generation hybrid Wells–Dawson POMs.

Herein, we report the synthesis and characterization of a new class of hybrid Wells–Dawson polyoxometalate (POM) containing a diphosphoryl group (P₂O₆X) of the general formula [P₂W₁₇O₅₇(P₂O₆X)]⁶⁻(X=O, NH, or CR¹R²). Modifying the bridging unit X was found to impact the redox potentials of the POM. The ease with which a range of α‐functionalized diphosphonic acids (X=CR¹R²) can be prepared provides possibilities to access diverse functionalized hybrid POMs. Compared to existing phosphonate hybrid Wells–Dawson POMs, diphosphoryl‐substituted POMs offer a wider tunable redox window and enhanced hydrolytic stability. This study provides a basis for the rational design and synthesis of next‐generation hybrid Wells–Dawson POMs.

The mixing of [V₁₀O₂₈]⁶⁻ decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self‐assembly of surfactant‐templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge‐like V₂O₅ (gem‐V₂O₅). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V₂O₅ consisting of very small crystallites (TBA‐V₂O₅). Electrochemical analysis of the materials’ performance as lithium‐ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long‐range microstructure of the gem‐V₂O₅ cathode deliver higher initial capacity and superior capacity retention than TBA‐V₂O₅. The smaller crystallite size and higher surface area of TBA‐V₂O₅ allow faster lithium insertion and superior rate performance to gem‐V₂O₅.

The mixing of [V₁₀O₂₈]⁶⁻ decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self‐assembly of surfactant‐templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge‐like V₂O₅ (gem‐V₂O₅). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V₂O₅ consisting of very small crystallites (TBA‐V₂O₅). Electrochemical analysis of the materials’ performance as lithium‐ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long‐range microstructure of the gem‐V₂O₅ cathode deliver higher initial capacity and superior capacity retention than TBA‐V₂O₅. The smaller crystallite size and higher surface area of TBA‐V₂O₅ allow faster lithium insertion and superior rate performance to gem‐V₂O₅.

A mixed‐addenda W/Mo hybrid polyoxometalate cluster – K₆[P₂W₁₅Mo₂O₆₁(POC₆H₅)₂] (1) was synthesised from the condensation of K₁₀[P₂W₁₅Mo₂O₆₁] and PO₃C₆H₇ under acidic conditions. Single‐crystal X‐ray diffraction confirmed the structure of the hybrid cluster and the presence of two Mo centres in the cap of the lacunary cluster. The electronic effects of metal substitution were studied by cyclic voltammetry, spectroelectrochemistry and electron paramagnetic resonance spectroscopy and supported by density functional theory calculations. Comparing 1 to its tungsten‐only analogue K₆[P₂W₁₇O₆₁(POC₆H₅)₂] (2), a more positive potential for the first reduction process was induced by the substitution of W for Mo, consistent with a significant lowering of the cluster LUMO energy.

The spontaneous self-assembly of hierarchical polyoxometalate-based nanostructures on a range of carbon surfaces is demonstrated via the use of amphiphilic hybrid-polyoxometalate building blocks.

We describe the preparation of hybrid redox materials based on polyoxomolybdates encapsulated within single‐walled carbon nanotubes (SWNTs). Polyoxomolybdates readily oxidize SWNTs under ambient conditions in solution, and here we study their charge‐transfer interactions with SWNTs to provide detailed mechanistic insights into the redox‐driven encapsulation of these and similar nanoclusters. We are able to correlate the relative redox potentials of the encapsulated clusters with the level of SWNT oxidation in the resultant hybrid materials and use this to show that precise redox tuning is a necessary requirement for successful encapsulation. The host–guest redox materials described here exhibit exceptional electrochemical stability, retaining up to 86 % of their charge capacity over 1000 oxidation/reduction cycles, despite the typical lability and solution‐phase electrochemical instability of the polyoxomolybdates we have explored. Our findings illustrate the broad applicability of the redox‐driven encapsulation approach to the design and fabrication of tunable, highly conductive, ultra‐stable nanoconfined energy materials.

We describe the preparation of hybrid redox materials based on polyoxomolybdates encapsulated within single‐walled carbon nanotubes (SWNTs). Polyoxomolybdates readily oxidize SWNTs under ambient conditions in solution, and here we study their charge‐transfer interactions with SWNTs to provide detailed mechanistic insights into the redox‐driven encapsulation of these and similar nanoclusters. We are able to correlate the relative redox potentials of the encapsulated clusters with the level of SWNT oxidation in the resultant hybrid materials and use this to show that precise redox tuning is a necessary requirement for successful encapsulation. The host–guest redox materials described here exhibit exceptional electrochemical stability, retaining up to 86 % of their charge capacity over 1000 oxidation/reduction cycles, despite the typical lability and solution‐phase electrochemical instability of the polyoxomolybdates we have explored. Our findings illustrate the broad applicability of the redox‐driven encapsulation approach to the design and fabrication of tunable, highly conductive, ultra‐stable nanoconfined energy materials.