Enhancing the Catalytic Activity of Pd Nanocatalysts for Anion Exchange Membrane Direct Ethanol Fuel Cells by Functionalizing Vulcan XC-72 with Cu Organometallic Compounds

The most widely used support in low-temperature fuel cell applications is the commercially available Vulcan XC-72. Herein, we report its functionalization with the home-obtained mesityl copper (Cu-mes) and Cu coordinate (Cu(dmpz)L2) organometallic compounds. Pd nanoparticles are anchored on the supports obtaining Pd/C_Cu-mes, Pd/C_Cu(dmpz)L2, and Pd/C (on nonfunctionalized support). The polarization curves of the ethanol oxidation reaction (EOR) show that Pd/C_Cu-mes and Pd/C_Cu(dmpz)L2 promote the reaction at a more negative onset potential, i.e., E _onset = 0.38 V/reversible hydrogen electrode (RHE), compared to 0.41 V/RHE of Pd/C. The mass current density (j _m) delivered by Pd/C_Cu-mes is considerably higher (1231.3 mA mg_Pd ^-1), followed by Pd/C_Cu(dmpz)L2 (1001.8 mA mg_Pd ^-1), and Pd/C (808.3 mA mg_Pd ^-1). The enhanced performance of Pd/C_Cu-mes and Pd/C_Cu(dmpz)L2 for the EOR (and tolerance to CO poisoning) is attributed to a shift of their d-band center toward more negative values, compared to Pd/C, because of the formation of PdCu alloyed phases arising from the functionalization. In addition, laboratory-scale tests of the anion exchange membrane-direct ethanol fuel cell assembled with Pd/C_Cu-mes show the highest open circuit voltage (OCV = 0.60 V) and cell power density (P _cell = 0.14 mW cm^-2). As a result of its high catalytic activity, Pd/C_Cu-mes can find application as an anode nanocatalyst in AEM-DEFCs.