Characterization of hierarchicalα-MoO₃plates toward resistive heating synthesis: electrochemical activity ofα-MoO₃/Pt modified electrode toward methanol oxidation at neutral pH

Abstract

The growth of MoO hierarchical plates was obtained by direct resistive heating of molybdenum foils at ambient pressure in the absence of any catalysts and templates. Plates synthesized after 60 min resistive heating typically grow in an single-crystalline orthorhombic structure that develop preferentially in the [001] direction, and are characterized by high resolution transmission electron microscopy, selected area diffraction pattern and Raman-scattering measurements. They are about 100-200 nm in thickness and a few tens of micrometers in length. As heating time proceeds to 80 min, plates of α-MoO form a branched structure. A more attentive look shows that primary plates formed at until 60 min could serve as substrates for the subsequent growth of secondary belts. Moreover, a full electrochemical characterization of α-MoO plates on platinum electrodes was done by cyclic voltammetric experiments, at pH 7 in phosphate buffer, to probe the activity of the proposed composite material as anode to methanol electro-oxidation. Reported results indicate that Pt MoO modified electrodes are appropriate to develop new an amperometric non-enzymatic sensor for methanol as well as to make anodes suitable to be used in direct methanol fuel cells working at neutral pH.

Synthesis and Characterization of Te Nanotubes Decorated with Pt Nanoparticles for a Fuel Cell Anode/Cathode Working at a Neutral pH

“…This observed behavior, together with the overall current density increment, and the potential range raising in the forward scan, with respect to the bare Pt, confirmed a synergic interaction between the Te and the Pt electroactive sites, which act to enhance the methanol electro-oxidation processes. methanol oxidation in the potential range between 0.00 mV and +600 mV, and a maximum of current density at around +370 mV vs. Ag/AgCl, according to the reported values at platinum electrodes in neutral pH vs. small molecular weight alcohol [35][36][37]. However, a rapid poisoning of the electrode at these high concentrations of methanol is observed.…”

“…Conventional GC electrode, as expected, was totally inactive with respect to methanol oxidation with current density levels ranging between −30 and 10 µAcm −2 , with no peak current observation after methanol addition. Otherwise, bare Pt electrodes present peaks in oxidation and reduction, related to the electrochemical activity involving the different oxidation states of platinum, showing a typical electrocatalytic activity toward methanol oxidation in the potential range between 0.00 mV and +600 mV, and a maximum of current density at around +370 mV vs. Ag/AgCl, according to the reported values at platinum electrodes in neutral pH vs. small molecular weight alcohol [35][36][37]. However, a rapid poisoning of the electrode at these high concentrations of methanol is observed.…”

α-MoO3 as a Conductive 2D Oxide: Tunable n-Type Electrical Transport via Oxygen Vacancy and Fluorine Doping

“…Peaks ranging from 0 to 200 cm –1 are associated with lattice modes, from 200 to 400 cm –1 are associated with deformation modes, and from 600 to 1000 cm –1 are associated with stretching modes . Presence of the terminal oxygen (Mo = O 1 ) is evidenced by peaks at 284 and 996 cm –1 , the doubly coordinated oxygen (Mo 2 –O) by peaks at 217, 245, and 819 cm –1 , and the triply coordinated oxygen (Mo 3 –O) by peaks at 332 and 667 cm –1 . All these Raman lines were observed in the spectra from our samples, except at 245 cm –1 .…”

“…From Figure , the expected peaks are observed at 115, 154, 198, 217, 284, 332, 667, 819, and 996 cm –1 for a typical α-MoO 3 sample. ,− These correspond to different oxygen bonds within the lattice. Peaks ranging from 0 to 200 cm –1 are associated with lattice modes, from 200 to 400 cm –1 are associated with deformation modes, and from 600 to 1000 cm –1 are associated with stretching modes . Presence of the terminal oxygen (Mo = O 1 ) is evidenced by peaks at 284 and 996 cm –1 , the doubly coordinated oxygen (Mo 2 –O) by peaks at 217, 245, and 819 cm –1 , and the triply coordinated oxygen (Mo 3 –O) by peaks at 332 and 667 cm –1 .…”

Synthesis and Characterization of Te Nanotubes Decorated with Pt Nanoparticles for Fuel Cell Anode/Cathode Working at Neutral pH

“…Otherwise bare Pt electrodes present peaks in oxidation and reduction related to the electrochemical activity involving the different oxidation states of platinum showing a typical electrocatalytic activity toward methanol oxidation in the potential range between 0.00 mV and +600 mV and a maximum of current density at around +370 mV vs Ag/AgCl, according to the reported values at platinum electrodes in neutral pH vs small molecular weight alcohols. [35][36][37] However, a rapid poisoning of the electrode at these high concentrations of methanol is observed. As a matter of fact, CV curves obtained at 500 mM (figure 6 B, trace Blue) and 1000 mM (figure 6 C, trace Blue) are almost coincident, with a tendency to decrease with the increase of methanol concentration.…”