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 Engineering electrochemical device integration
and understanding electrochemical processes

  • Fabrication of colloidal nanoparticle-based electrode for Proton Exchange Membrane Water Electrolyzer (PEMWE)

The inherent properties of nanoparticles (NPs) can be engineered into macroscopic structures by capturing the collective characteristics of the nanomaterials via a fabrication process to realize macroscopic functionality. We report a powerful manufacturing technique for fabricating an electrocatalytic electrode composed of highly porous iron phosphide (FeP) NP catalyst layers conformally deposited on macroporous carbon paper (CP) that shows excellent hydrogen evolution reaction activity.

The surface morphology and porosity of the FeP NP catalyst layers on the FeP/CP electrode were tuned by altering the deposition kinetics of the colloidal FeP NPs by controlling the solvent system in the electrophoretic deposition process. The FeP/CP electrode achieved a low overpotential of 38 mV at 10 mA cm−2 in 0.5 M H2SO4 due to the highly exposed catalytic surface with a large catalyst loading amount and fast charge transfer. When the FeP/CP electrode was applied as a cathode gas diffusion electrode (GDE) in a proton exchange membrane water electrolyzer (PEMWE), the single-cell exhibited excellent operating performance (1.48 A cm−2 @ 2.0 Vcell, 90°C). Our fabrication process to produce electrocatalytic electrodes with a controlled solvent system provides the opportunity for various non-precious colloidal NP catalysts to be realized as highly efficient GDEs in low-cost PEMWEs.

Park, Yoonsu, et al. Chemical Engineering Journal (2021)

  • Transition metal nanoparticle synthesis for hydrogen evolution reaction catalysis

FeP NPs are synthesized with various phosphorus sources (TOP, trioctylphosphine; TPP, triphenylphosphite; TEAP, tris(diethylamino)phosphine; and TBP, tri-n-butylphosphine) via phosphorization reaction. We clearly demonstrate that the HER activity of the catalyst based on the FeP phase is dependent on the choice of phosphorus source used in the colloidal NP synthesis. Among the samples, FeP NPs synthesized with TPP achieved the highest HER activity with an overpotential of 76 mV at 10 mA cm-2 in 0.5 M H2SO4.

We report the spherical iron phosphide nanoparticles (FeP NPs) doped with various transition metals (Mn, Co, and Ni) via a phosphorization process from Fe-based bimetallic NPs and characterize the changes in their HER activity as a result of doping with different elements. X-ray absorption spectroscopy analysis revealed substitutional doping of Fe atoms by Co atoms in the FeP crystalline structure.

Park, Yoonsu, et al. International Jounrnal of Hydrogen Energy 45.57 (2020)

Cho, Geonhee, et al. Applied Surface Science 510 (2020)

  • Colloidal synthetic methods of amorphous molybdenum phosphide nanoparticles for hydrogen evolution reaction catalysts

We systematically compared two different colloidal synthetic methods (one-pot and two-step) for amorphous MoP and the related morphological changes during their reaction time.

The amorphous MoP nanoparticles synthesized by the two-step method within 4 h showed the high HER catalytic activity with an overpotential of 177 mV in 0.50 M H2SO4 for a current density of –10 mA cm–2; this result might be due to their more abundant Mo–P bondings revealed by X-ray photoelectron spectroscopy analysis.

Thus, this work demonstrates that the synthetic method and the reaction time can significantly influence the HER performance of MoP catalysts.

Kang, Hyeri, et al. Korean Journal of Chemical Engineering 37.8 (2020)

캡처.PNG

D.-H. Ha et al. Nano Lett. 12, 5122 (2012)
D.-H. Ha et al. ACS Appl. Mater. Interfaces 7, 25053 (2015)

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