Use of X-ray Tomography for the Experimental Verification of a Mathematical Model for the Recovery of Cu and Cd in a Flow-By Porous Electrode Reactor.

Boardman

et al. 2017

Electrochimica Acta

Platinised titanium mesh is a common electrode material in industrial electrolytic cells and Cebased redox flow batteries. In this work, the electrodeposition of platinum on a stack of titanium micromeshes is carried out from a flowing alkaline solution in a rectangular channel, divided flow cell. The morphology and distribution of platinum deposits are studied by SEM, EDS mapping and X-ray computer tomography. The active surface area of the electrode was assessed from the charge transfer current for the reduction of Ce(IV) and compared to that of planar and expanded metal mesh electrodes. The surface area was estimated by hydrogen electrosorption relative to that at a planar Pt/Ti electrode. As expected from the potential drop within the electrode channel, the individual micromesh near the cell separator displayed a higher platinum content. Pt/Ti micromesh offers an extended surface area and enhanced mass transport compared to planar electrodes and conventional expanded metal mesh anodes. The applications for these and alternative electrode structures are discussed.

Section: Pt Distribution Within the Micromesh As Revealed By Ctmentioning

confidence: 86%

Characterisation of platinum electrodeposits on a titanium micromesh stack in a rectangular channel flow cell

Arenas

Boardman

et al. 2017

Electrochimica Acta

“…The study of RVC's volumetric surface area by µCT has not been reported, although the cell size of a tannin-based RVC specimen was recently measured by this technique [46]. (Studies of metal deposit distribution on RVC substrates using radiography [47] and low-resolution CT [48] are available.) However, scanning conditions must be first established for maximum accuracy.…”

Section: Volumetric Surface Area Of Rvcmentioning

confidence: 99%

X-ray computed micro-tomography of reticulated vitreous carbon

Arenas

Boardman

et al. 2018

Carbon

The 3D structure of various grades of reticulated vitreous carbon (RVC) is studied by X-ray computed micro-tomography (µCT). The settings required to estimate the bulk volumetric surface area accurately are investigated and the results are compared to those obtained from scanning electron microscopy and from pressure drop measurements via the Ergun equation. A resolution of 1.3 µm per voxel in µCT imaging is needed to determine the volumetric surface area, but its value is highly dependent on post-processing. A resolution of 9.6 µm per voxel underestimated the volumetric surface area, Ae, by a factor of up to 0.64 due to an incomplete resolution of the cell struts. This latter resolution is, however, sufficient to establish the volumetric porosity and the relative density. Theoretical estimations of electrical resistivity using these properties are consistent with those reported in the literature. Cell volume and cell surface area distributions are then obtained from computational analysis of the digitally rendered structure of 100 ppi RVC. Both cases can be approximated by a gamma function. Suitable instrumental µCT conditions for performing metrological studies on bare and modified RVC are proposed. Opportunities for the modelling of decorated and coated digitally rendered RVC are discussed.

“…32 The physical surface area of these materials and its comparison to active electrochemical surface area is particularly important in electrochemical studies. 33,34 Examples involving conventional porous electrodes by CT include the tortuosity of carbon (C) felt, 35 the surface area of reticulated vitreous carbon (RVC) 31 and the distribution of metal deposits such as Cu and cadmium (Cd) 36 or Pt. 37,38 Related examples of the analysis of inert porous materials by CT include the determination of pore diameter distribution in SiC-Al 2 O 3 foams 39 and the study of porosity and tortuosity in SiC foams.…”

Section: Introductionmentioning

confidence: 99%

Design, imaging and performance of 3D printed open‐cell architectures for porous electrodes: quantification of surface area and permeability

Kaishubayeva

J of Chemical Tech & Biotech

Walsh

et al. 2021

BACKGROUND:The development of new open-cell porous electrodes for electrochemical flow cells and reactors is demonstrated through the application of 3D printing. The properties of diverse architectures were investigated, including rectangular, circular, hexagonal and triangular cells with linear porosity grades of 10, 20 and 30 pores per inch (ppi). Specimens were digitally designed, then 3D printed in stainless steel via selective laser melting. After being examined using scanning electron microscopy, they were characterized in terms of volumetric surface area and porosity with the aid of X-ray computed tomography. Pressure drop measurements were performed over a range of mean linear velocity and Reynolds number, allowing the estimation of Darcy's friction factor and permeability.RESULTS: Volumetric surface area estimated from tomography scans was ≤36% higher than the nominal values owing to surface roughness and post-processing algorithms. By contrast, volumetric porosity obtained by tomography agreed fully with measured values. Triangular architectures afforded additional surface area both digitally and according to tomography. The largest pressure drop was found in circular materials, the triangular ones showing the lowest. The 20 ppi triangular architecture had a volumetric surface area of ≈44.5 cm −1 and a permeability of 2.31 × 10 −5 cm 2 . CONCLUSION: Triangular architectures were preferred as a consequence of their favourable combination of high surface area and high permeability with low mass and reduced digital complexity. This provides a strategy to initiate the optimization of 3D printed porous electrodes for electrochemical flow cells and reactors in novel and niche applications.