Oxygen Reduction Reaction Performance Tuning on Pt Nanoparticle/MWCNT Catalysts by Gd Species

Abstract

Fine Pt nanoparticles functionalized with Gd 3+ hydroxide/oxide species were prepared on multiwalled carbon nanotubes (MWCNTs) containing polypyrrole matrix overlayers and found to exhibit remarkable electrocatalytic performance in the oxygen reduction reaction (ORR). Characterization via transmission electron microscopy, scanning transmission electron microscopy with electron energy loss spectroscopy, X-ray absorption fine structure, and X-ray photoelectron spectroscopy revealed that the Gd 3+ hydroxide/oxide species were located in close proximity to the Pt 0 nanoparticles on the MWCNTs. The prepared Pt nanoparticle−Gd hydroxide/oxide composites exhibited superior ORR activity to Gd-free Pt nanoparticles prepared in a similar manner, and the decoration with the Gd species suppressed Pt oxidation and accelerated Pt oxide reduction, as demonstrated by cyclic voltammetry and in situ Pt L III -edge X-ray absorption near-edge structure analysis under potential application. The effect of the Gd loading on the ORR performance was also examined, revealing the existence of an optimal Gd loading beyond which further Gd incorporation resulted in aggregation of the Gd 3+ domains and decreased crystallinity of the Pt nanoparticles.

Hydrogenated Boride-Assisted Gram-Scale Production of Platinum–Palladium Alloy Nanoparticles on Carbon Black for PEMFC Cathodes: A Study from a Practical Standpoint

“…The ORR free energy profiles for Pt(111) and PtPd(111) and slabs are similar to each other, and all of the free energy changes are negative, indicating that all of the elementary steps are exothermic and thermodynamically spontaneous. The adsorption energies of *OOH and *OH on the PtPd(111) slab is lower than those on the Pt(111) slab by 0.029 and 0.068 eV, respectively, revealing that the PtPd(111) surface can weaken the adsorption of *OOH and *OH and release more active sites for ORR, − consistent with the experimental conclusions.…”

A novel fuel cell design for operando energy-dispersive x-ray absorption measurements

“…Overall compression of the cell is provided via tie-rods in the endplates than in turn compress the bipolar plate material, which is rigid and therefore translates this compression of the MEA over the measurement window, ensuring good electrical contact in the area of spectroscopic measurement. This differentiates the cell presented in this work from those previously published, as previously published cells use Kapton windows [22][23][24] where the area of MEA measured will have reduced compression and therefore will not be in a representative environment of the whole cell. Additionally, the window position allows spatially resolved measurements to be conducted perpendicular to the MEA, at different points along the flow field or in channels or land area.…”

“…[20] It is therefore important to move towards the evaluation of catalysts in real working fuel cells (or as close as possible), by employing gas diffusion electrodes and truly operando environments. [21] Among the few examples of operando studies using X-ray spectroscopy of fuel cell catalysts there are several reports from the Tada group [22][23][24] using a bespoke cell with Kapton windows at SPring-8 synchrotron facility (Japan), and a cell that was developed by the Russell group for use at Daresbury Laboratory (UK) and the ESRF (France). [25,26] The cell used by the Tada group was optimised for computed tomography (CT) and incorporates a long thin slit across the whole width of the cell, allowing measurements that are taken at 10 degrees incidence to the plane of the electrode, across a channel in the flow field.…”

The Journal of Physical Chemistry C Virtual Special Issue on Advanced Characterization by Solid-State NMR and In Situ Technology and in Recognition of Michael Hunger’s 65th Birthday

“…Other in situ spectroscopic technologies are also reported in the VSI. The Tada group revealed the mechanism of Pt nanoparticle–Gd hydroxide/oxide composites exhibiting superior oxygen reduction reaction (ORR) activity by in situ XAS . Yao and coworkers used in situ XAS to detect the doping effect on the atomic and electronic structure of Se active sites during the hydrogen evolution reaction (HER) .…”

“…The Tada group revealed the mechanism of Pt nanoparticle−Gd hydroxide/oxide composites exhibiting superior oxygen reduction reaction (ORR) activity by in situ XAS. 36 Yao and coworkers used in situ XAS to detect the doping effect on the atomic and electronic structure of Se active sites during the hydrogen evolution reaction (HER). 37 New-generation synchrotrons combined with focusing beamlines provide high-flux-density X-rays for improved detection sensitivity as well as higher time and spatial resolution.…”