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Published May 5, 2021 | Supplemental Material
Journal Article Open

3D Printed Nickel–Molybdenum-Based Electrocatalysts for Hydrogen Evolution at Low Overpotentials in a Flow-Through Configuration

Abstract

Three-dimensional (3D) printed, hierarchically porous nickel molybdenum (NiMo) electrocatalysts were synthesized and evaluated in a flow-through configuration for the hydrogen evolution reaction (HER) in 1.0 M KOH(aq) in a simple electrochemical H-cell. 3D NiMo electrodes possess hierarchically porous structures because of the resol-based aerogel precursor, which generates superporous carbon aerogel as a catalyst support. Relative to a traditional planar electrode configuration, the flow-through configuration allowed efficient removal of the hydrogen bubbles from the catalyst surface, especially at high operating current densities, and significantly decreased the overpotentials required for HER. An analytical model that accounted for the electrokinetics of HER as well as the mass transport with or without the flow-through configuration was developed to quantitatively evaluate voltage losses associated with kinetic overpotentials and ohmic resistance due to bubble formation in the porous electrodes. The chemical composition, electrochemical surface area (ECSA), and roughness factor (RF) were also systematically studied to assess the electrocatalytic performance of the 3D printed, hierarchically porous NiMo electrodes. An ECSA of 25163 cm² was obtained with the highly porous structures, and an average overpotential of 45 mV at 10 mA cm⁻² was achieved over 24 h by using the flow-through configuration. The flow-through configuration evaluated in the simple H-cell achieved high electrochemical accessible surface areas for electrochemical reactions and provided useful information for adaption of the porous electrodes in flow cells.

Additional Information

© 2021 American Chemical Society. Received: March 26, 2021; Accepted: April 12, 2021; Published: April 22, 2021. The materials synthesis work at LLNL was performed under the auspices of the US Department of Energy under Contract DE-AC52-07NA27344, and this work was supported by funding from LDRD Awards 19-SI-005 and 19-FS-047 and IM review # LLNL-JRNL-816169. The characterization and analytical calculation of the flow-through electrodes are based on work performed by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award DE-SC0021266. Author Contributions. I.S. performed the electrochemical measurements, materials characterization, SEM imaging, and electrode fabrication. S.L. performed synthesis of the resin and NiMo substrates. A.J.N. performed XPS measurements and analysis. All authors contributed to conceptualization of the research and assisted with preparing, writing, and editing the manuscript. The authors declare no competing financial interest.

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Created:
August 20, 2023
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October 23, 2023