Density gradient films, lanthanide electrochemistry, and magnetic field effects on hydrogen evolution, oxygen reduction, and lanthanide electrochemistry

Abstract

and Matt Lovander for their friendship and support. I thank the University of Iowa Department of Chemistry and the National Science Foundation for …nancial support. I am thankful to my family, my parents, Randy and Becky Knoche, my sister Jennifer Knoche, and my brother Travis Knoche, for their love and inspiration through the years. I thank my college roommate Aidan Leddy for her awesome friendship and my love Shuvra Gupta for his inspiration and amazing con…dence in me.

Magnetoelectrocatalysis: Evidence from the Hydrogen Evolution Reaction

“…To differentiate impacts of magnetic fields and magnetic gradients, the electrochemical cell is centered in a hollow cylinder rare earth permanent magnet (Figure SI.2) to establish a strong uniform field perpendicular to the electrode surface. 4 For the unmodified Pt disk, the uniform field of the external ring magnet enhances current near 1.05 V vs SCE by 65% (Figure 3 top). The uniform magnetic field interacts with ions mobile in the electrolyte to generate a Lorentz force that induces bulk fluid flow and enhances current through mass transport.…”

“…Diamagnetic GC is a poor HER electrocatalyst. LSVs for modified GC electrodes are shown in Figure 2 for (a) magnetized and (c) demagnetized γ-Fe 2 O 3 C1, C3, and C8 composites 4 and for (b) Fe 3 O 4 composites. 5 Details are listed in SI.…”

“…LSV in N 2 degassed 0.10 M HNO 3 at Pt disks modified with Nafion films and magnetized 15% v/v γ-Fe 2 O 3 C1, C3, and C8 composites superimpose in the kinetically controlled range below 1 mA cm −2 (SI.5.1.1, SI.6, and Figure 2d). 4 At higher current densities and longer times, magnetic field dependent transport in the electrolytes spreads LSV currents once the diffusion length exceeds film thickness. In Table 1 for replicate measurements, ΔE = E mag − E Naf is +(0.007 ± 0.005) V. With >90% confidence, E mag and E Naf are not statistically different.…”

“…Rates invariably increased where magnetized composites modify diamagnetic electrodes of GC, Au, and Hg pool and photocathodes of n-GaAs and p-Si. 4,5 Here, details for GC are reported. Magnetized Composites on Diamagnetic GC Electrodes-Enhanced Rates.…”

“…In all cases, magnetized composites on diamagnetic electrodes amplify electrocatalytic rates, typically in the range of 10−1000 times. 4,5 Notably, composites formed with demagnetized microparticles evolve H 2 at rates comparable to or slightly lower than Nafion films. Chemical composition of magnetized and demagnetized composites is the same, but the physical distinction of magnetic gradients drives substantially higher HER rates on diamagnetic electrodes.…”