Multifunctional Core–Shell Particle Electrodes for Application in Fluidized Bed Reactors

Abstract

Fluidized particle electrodes are well-suited for a wide range of electrochemical reactions due to their large specific surface area and their tolerance toward suspended solid contaminants and gas bubbles. For effective electrode performance, particles require (i) high conductivity, (ii) efficient interparticle contact, and (iii) chemical inertness toward a broad range of reagents and solvents. In particular, sufficient interparticle contact remains a critical challenge. Magnetic stabilization of the fluidized bed provides a potential solution but requires the use of magnetic electrode materials. However, the synthesis of electrode particles with high magnetic susceptibility remains an ongoing challenge. Herein, electrojetting of magnetite/poly(methyl methacrylate) suspensions into a graphite powder bed is demonstrated to be a facile and effective route toward magnetically stabilizable electrode particles. Energy-dispersive X-ray spectroscopy and Raman spectroscopy confirmed the composition and core−shell structure of the particles. Characterization of their magnetic and electric properties showed an exceptionally high saturation magnetization of 11.1 A•m 2 /kg and a conductivity of 28 S/m. Further, scanning electron microscopy revealed an average diameter of approximately 200 μm, large surface areas, and spherical shapes, three prerequisites for homogeneous fluidization. Compared to previously reported fluidized bed electrodes, electrodes comprised of these novel core/shell particles showed 2-fold increases in current densities and conversion rates. These results underline the potential of the electrohydrodynamic jetting process for the design and synthesis of novel, tailor-made core−shell particles as key components of fluidized bed electrodes for electrochemical reactions.