A fundamental understanding of the hydrogen oxidation reaction (HOR) mechanism requires the synthesis of model catalysts with designed surfaces, and advanced characterization techniques of the active sites. Although HOR are fast under acidic conditions, HOR kinetics are sluggish under alkaline conditions, even on platinum group metals (PGMs). Herein, we propose the use of an effective high-surface-area carbon supported Pd/γ-NiOOH HOR electrocatalyst, made from organometallic precursors. The enhanced activity, provided by nickel oxy-hydroxide (γ-NiOOH) 2 nm nanocubes, was confirmed experimentally in an alkaline exchange membrane fuel cell. Contrary to previous reports, the phase and crystallographic orientation of the γ-NiOOH nanocubes (<2 nm in size) were fully ascribed through high-resolution transmission electron microscopy.OperandoX-ray absorption spectroscopy revealed a redox behavior of Pd and Ni during the electrocatalysis. Each phase has an attributed role in the mechanism,i.e., hydrogen binding to the Pd metal and hydroxide binding to the γ-NiOOH, confirming the theory and experiments observed with bimetallic structures.
Bibliographical noteFunding Information:
This work was partially supported by the TEPS Magnet program from the Innovation authority, and Israeli Ministry of Science, Technology & Space for its financial support. Dr. Qingying Jia acknowledges the use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Use of Beamline 2-2 at SSRL was supported by the National Synchrotron Light Source (NSLS) II, Brookhaven National Laboratory, under U.S. DOE Contract No. DE-SC0012704.
© The Royal Society of Chemistry 2020.