Nonstoichiometric CeO(2) and Ce(0.25)Zr(0.75)O(2) nanoparticles with varying surface concentrations of Ce(3+) were synthesized. Their concentration was measured by XPS, their oxygen vacancy grain size estimated using Raman spectroscopy. The found to correlate well concentration. When incorporated into a Nafion polymer electrolyte membrane (PEM), the added nonstoichiometric ceria effectively scavenged PEM-degradation-inducing free radical reactive species (ROS) formed during fuel cell...

The efficacy of nanoparticles in mitigating free-radical-induced polymer electrolyte membrane (PEM) degradation is investigated. Commercially obtained and synthesized in-house were incorporated within a recast Nafion membrane. Membrane electrode assemblies prepared using composite membranes (0.5, 1, ). exhibited very similar proton conductivities hydrogen crossover as Nafion. However, the fluoride emission rate (from accelerated tests) was lowered by more than 1 order magnitude upon addition...

Polysulfone (PSF) backbones were functionalized with reactive chloromethyl groups for preparing thin film anion exchange membranes (AEMs) fixed benzyl quaternary cations. Three different cation chemistries of varying basicity evaluated: 1,4-dimethylpiperazinium (DMP+), trimethylammonium (TMA+), and trimethylphosphonium (TMP+). The water uptake, ionic conductivity, stability in alkaline media these AEMs assessed both chloride hydroxide counteranions. results obtained revealed that the value...

Solid-state alkaline water electrolysis using a pure feed offers several distinct advantages over liquid electrolyte and proton exchange membrane electrolysis. These include larger array of electrocatalyst available for oxygen evolution, no management, the ability to apply differential pressure. To date, there have been only handful reports on solid-state electrolyzers anion membranes (AEMs), that investigate loss in system performance time. In this work, electrolyzer was successfully...

We report a unique and highly stable electrocatalyst-platinum (Pt) supported on titanium-ruthenium oxide (TRO)-for hydrogen fuel cell vehicles. The Pt/TRO electrocatalyst was exposed to stringent accelerated test protocols designed induce degradation failure mechanisms identical those seen during extended normal operation of automobile-namely, support corrosion vehicle startup shutdown, platinum dissolution acceleration deceleration. These experiments were performed both ex situ (on supports...

Lead ruthenate pyrochlore showed exceptional OER activity and stability when tested in a solid-state alkaline water electrolyzer.

A polysulfone-based anion exchange membrane functionalized with quaternary benzyl trimethylammonium groups (PSF-TMA+) demonstrated a 40-fold reduction in vanadium(IV) permeability when compared to Nafion® membrane. Comprehensive 2D NMR (COSY and heteronuclear quantum correlation spectroscopy) studies verified that PSF-TMA+ remained chemically stable even after exposure 1.5 M vanadium(V) solution for 90 days. Excellent energy efficiencies (85%) were attained sustained over several...

Alkaline fuel cells containing anion exchange membrane electrolytes (i.e., solid-state alkaline - SAFCs) promise to provide high power densities without platinum group metal catalysts. In the past decade, SAFC performance has improved substantially due improvements in electrode binders that facilitate good membrane-electrode contact and ionic conductivity layer. However, (in)stability of AEMs is a long-standing challenge currently precludes commercialization this technology. To date, there...

The stability of cardo-poly(etherketone) based anion exchange membranes was investigated by performing 1-D and 2-D HMQC NMR spectroscopy.

Micro-tomography (CT) can be successfully employed to characterize ex situ the structural changes occurring in graphite felt electrodes during vanadium redox flow battery (VRFB) operation. Coupled high resolution X-ray and electron microscopy conjunction with XPS are used elucidate microstructural chemical voltage RFB carbon electrode. The results reveal onset of corrosion structure relatively early VRFB life-cycle, extended operation is expected result extensive evolution effects.

The degradation of quaternary ammonium-cation-sites in PPO-based AEMs alkali was considerably faster the presence oxygen.

This study investigates the effect of thermal activation all-vanadium redox flow battery (RFB) carbon-felt electrodes on their electrode kinetics. Using X-ray photoelectron spectroscopy, is shown to increase content C–OH group, decrease C═O and not affect O–C═O with all these surface moieties already being present in nonactivated carbon felt. Rotating disk studies were performed using custom fabricated felt investigate kinetics V2+/V3+ VO2+/VO2+ couples H2SO4 deconvolute impact We...

CeO(2), Pt/CeO(2) and MnO(2) additives were found to lower the rate of free radical induced polymer electrolyte membrane degradation in an operating fuel cell by over one order magnitude.

Abstract The objectives of this study were: 1) to confirm superoxide anion radical (O 2 .− ) formation, and 2) monitor in real time the rate O generation an operating exchange membrane (AEM) fuel cell using situ fluorescence spectroscopy. 1,3‐Diphenlisobenzofuran (DPBF) was used as fluorescent molecular probe owing its selectivity sensitivity toward alkaline media. activation energy for during AEM operation estimated be 18.3 kJ mol −1 . correlated well with experimentally measured loss...

PtCo/C and Pt/C catalyst powders were incorporated into electrospun nanofiber conventional sprayed cathode membrane-electrode-assemblies (MEAs) at a fixed electrode loading of 0.1 mgPt/cm2. The binder for cathodes anodes was mixture Nafion poly(acrylic acid) (PAA), whereas the MEAs utilized neat binder. structure fibers analyzed by scanning transmission electron microscopy (STEM) energy-dispersive X-ray spectroscopy (EDS), which showed that ∼30% porous with uniform distribution in axial...

Anion exchange membranes (AEMs) with hexyl pendant chains were synthesized by Friedel–Crafts acylation of 6-bromo-1-hexanoyl chloride on poly(phenylene oxide) (PPO), followed the reduction ketone triethylamine, and quaternization a tertiary amine (trimethylamine, quinuclidine, or 1-methylimidazole). 1H-NMR, 13C-NMR, COSY HMQC NMR spectroscopies used to prove formation brominated polymers assess alkaline stability AEMs. The trimethylamine (TMA) based AEMs was evaluated using two separate,...

The kinetics of hydrogen evolution and oxidation reactions (HER/HOR) in alkaline electrolyte on Pt/C a Pt/C/Ni(OH)2 bi-functional electrocatalyst were studied. objective was to investigate the enhancement activity Pt environments presence transition metal hydroxides, determine optimum concentration Ni(OH)2 be added maximize catalytic activity. catalysts prepared by mixing colloidal dispersions nanosized with commercially-sourced catalyst dispersed water. Rotating disk electrode (RDE)...

In this work, we investigate the performance and degradation of polyphenylene oxide (PPO) based AEMs in a solid-alkaline water electrolyzer at 50°C using electrochemical testing 1-D 2-D NMR spectroscopy. The PPO were derivatized with trimethylamine (TMA) quinuclidine (ABCO) to yield TMA+ ABCO+ cations. underwent chemical during electrolysis. cell voltage 0.2 A/cm2 for BrPPO-ABCO+ BrPPO-TMA+ increased by 0.4 V respectively after 5 hours operation 0.1 A/cm2. Postmortem analysis membrane AEM...

The oxygen permeability of perfluorinated and hydrocarbon polymer electrolyte membranes (PEMs; Nafion®, SPEEK SPSU), which are used as electrolytes electrode ionomers in fuel cells (PEFCs), was estimated using chronoamperometry a modified cell set-up. A thin, cylindrical microelectrode embedded into the PEM working electrode. sandwiched between 2 gas diffusion electrodes, one catalyzed served counter pseudo-reference Independently, from experiments, transport resistance arising due to...

The lifetime of commercial proton exchange membrane fuel cells (PEMFCs) is circumscribed by the insufficient durability catalysts. use metal oxide supports in place carbon significantly increases electrocatalyst durability. Herein, following density functional theory predictions improved platinum (Pt) stability on antimony-doped tin (ATO) supports, we synthesized ATO whose morphology and crystal structure were engineered using a Pt-anchoring technique. X-ray photoelectron spectroscopy...

The electrochemical supercapacitor performance of MnO2 is significantly influenced by the phase structure due to various structural features different polymorphs that include tunnels or layered structures can facilitate ion transport and intercalation. However, effect crystal within MnO2/carbon composites has not been fully explored understood. Herein, we have synthesized (α- β-MnO2) MnO2/reduced graphene oxide (rGO) a hydrothermal process using amounts (NH4)2SO4, followed systematic...