2 research outputs found
Layer-by-Layer Construction of a Nanoarchitecture by Polyoxometalates and Polymers: Enhanced Electrochemical Hydrogen Evolution Reaction
In this contribution, a nanoarchitectural approach was
employed
to produce a nanolayer of polyoxometalate (POM) on the surface of
a glassy carbon electrode (GCE) to achieve a higher surface area with
higher electrocatalytic activity toward the electrochemical hydrogen
evolution reaction (HER). To accomplish this, the well-known layer-by-layer
(LbL) technique was employed, which involved the alternate adsorption
of the POM, Na0.3[N(C4H9)4]7.7 [(Mo3O8)4(O3PC(O)(C3H6NH2CH2C4H3S)PO3)4], abbreviated
as [(TBA)Mo12(AleThio)4], and polyethyleneimine
(PEI) polymer. This nanolayered electrode exhibited catalytic properties
toward the HER in 0.5 M H2SO4 with the resulting
polarization curves indicating an increase in the HER activity with
the increasing number of POM layers, and the overpotential required
for this reaction was lowered by 0.83 V when compared with a bare
GCE. The eighth PEI/[(TBA)Mo12(AleThio)4] bilayer
exhibited a significantly lower HER overpotential of −0.077
V at a current density of 10 mA cm–2. Surface characterization
of the LbL-assembled nanolayers was carried out using X-ray photoelectron
spectroscopy, atomic force microscopy, and scanning electron microscopy.
We believe that the synergetic effect of the positively charged PEI
polymer and the catalytically active molybdate POM is the cause for
the successful response to the electrochemical HER
Organic−Inorganic Hybrid Films of the Sulfate Dawson Polyoxometalate, [S2W18O62] 4−, and Polypyrrole for Iodate Electrocatalysis
The Dawson-type sulfate polyoxometalate (POM) [S2W18O62]4− has successfully been entrapped in polypyrrole (PPy) films on glassy carbon electrode (GCE) surfaces through pyrrole electropolymerization. Films of varying POM loadings (i.e., thickness) were grown by chronocoulometry. Film-coated electrodes were then characterized using voltammetry, revealing POM surface coverages ranging from 1.9 to 11.7 × 10−9 mol·cm−2 , and were stable over 100 redox cycles. Typical film morphology and composition were revealed to be porous using atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, and the effects of this porosity on POM redox activity were probed using AC impedance. The hybrid organic− inorganic films exhibited a good electrocatalytic response toward the reduction of iodate with a sensitivity of 0.769 μA·cm−2 ·μM−1 . </p