Enhancing the Catalytic\nActivity of Pd Nanocatalysts\nfor Anion Exchange Membrane Direct Ethanol Fuel Cells by Functionalizing\nVulcan XC-72 with Cu Organometallic Compounds

The most widely used\nsupport in low-temperature fuel\ncell applications\nis the commercially available Vulcan XC-72. Herein, we report its\nfunctionalization with the home-obtained mesityl copper (Cu-mes) and\nCu coordinate (Cu(dmpz)L2) organometallic compounds. Pd nanoparticles\nare anchored on the supports obtaining Pd/C<sub>Cu‑mes</sub>, Pd/C<sub>Cu(dmpz)L2</sub>, and Pd/C (on nonfunctionalized support).\nThe polarization curves of the ethanol oxidation reaction (EOR) show\nthat Pd/C<sub>Cu‑mes</sub> and Pd/C<sub>Cu(dmpz)L2</sub> promote\nthe reaction at a more negative onset potential, i.e., <i>E</i><sub>onset</sub> = 0.38 V/reversible hydrogen electrode (RHE), compared\nto 0.41 V/RHE of Pd/C. The mass current density (<i>j</i><sub>m</sub>) delivered by Pd/C<sub>Cu‑mes</sub> is considerably\nhigher (1231.3 mA mg<sub>Pd</sub><sup>–1</sup>), followed by\nPd/C<sub>Cu(dmpz)L2</sub> (1001.8 mA mg<sub>Pd</sub><sup>–1</sup>), and Pd/C (808.3 mA mg<sub>Pd</sub><sup>–1</sup>). The enhanced\nperformance of Pd/C<sub>Cu‑mes</sub> and Pd/C<sub>Cu(dmpz)L2</sub> for the EOR (and tolerance to CO poisoning) is attributed to a shift\nof their d-band center toward more negative values, compared to Pd/C,\nbecause of the formation of PdCu alloyed phases arising from the functionalization.\nIn addition, laboratory-scale tests of the anion exchange membrane-direct\nethanol fuel cell assembled with Pd/C<sub>Cu‑mes</sub> show\nthe highest open circuit voltage (OCV = 0.60 V) and cell power density\n(<i>P</i><sub>cell</sub> = 0.14 mW cm<sup>–2</sup>). As a result of its high catalytic activity, Pd/C<sub>Cu‑mes</sub> can find application as an anode nanocatalyst in AEM-DEFCs.