Integration of vanadium-mixed addenda Dawson heteropolytungstate within poly(3,4-ethylenedioxythiophene) and poly(2,2′-bithiophene) films by electrodeposition from the nonionic micellar aqueous medium

Defected MoS2 Modified by Vanadium-Substituted Keggin-Type Polyoxometalates as Electrocatalysts for Triiodide Reduction in Dye-Sensitized Solar Cells

The rational design of efficient triiodide reduction reaction catalysts that are dependent on cheap and ample elements on Earth has become a challenge. As an extremely encouraging non-noble metallic catalyst, MoS₂ requires effective strategies to improve the site accessibility, inherent conductivity, and structural stability. Here, vanadium-substituted Keggin-type polyoxometalates (POMs) can be used as electron aggregates to modify manganese (Mn)-doped MoS₂ through the electrochemical deposition strategy, thereby improving the charge transfer ability of MoS₂ to I^-/I₃^- redox pairs and accelerating the reduction of I₃^-. Additionally, with the increase in the number of vanadium atoms substituted in POMs, the conduction band of POMs and MoS₂ can also match better, which effectively reduces the energy loss and is more conducive to charge transfer. Meanwhile, the deposition of POMs can improve the stability of metastable MoS₂. When POMs/MoS₂ materials are used as the counter electrodes of dye-sensitized solar cells, the power conversion efficiency (PCE) obtained is 7.27%, which is higher than that of platinum (Pt) (6.07%). The PCE can still maintain the initial 96% after 9 days. This work provides a valuable way for the improvement of platinum-free catalysts with minimal expense, basic process, high efficiency, and good stability.

Transition Metal-Substituted Krebs-Type Polyoxometalate-Doped PEDOT Films

The transition metal-substituted Krebs-type polyoxometalates (POMs) [Sb₂W₂₀M₂O₇₀(H₂O)₆]^n-, M = Fe(III), Co(II), or Cu(II), were surface immobilized within the conducting polymer 3,4-ethylenedioxythiophene (PEDOT) on glassy carbon electrode surfaces. The immobilized films of different thicknesses were characterized by electrochemical and surface-based techniques. The inherent redox activity for the Krebs-type POMs, [Sb₂W₂₀M₂O₇₀(H₂O)₆]^n-, M = Fe(III), Co(II), or Cu(II), that were observed in the solution phase were maintained in the polymeric PEDOT matrix. The resulting films were found to be extremely stable toward redox switching between the various POM-based redox states. The films exhibited pH-dependent redox activity and thin layer behavior up to 100 mV s^-1. The films were found to be highly conductive through the employment of electrochemical impedance spectroscopy. Surface characterization of the films was carried out by X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy graph.

15-Copper(ii)-containing 36-tungsto-4-silicates(iv) [Cu15O2(OH)10X(A-α-SiW9O34)4]25−(X = Cl, Br): synthesis, structure, magnetic properties, and electrocatalytic CO2reduction

Two novel Cu₁₅-containing polyoxometalates are active and selective catalysts for electrochemical CO₂reduction.