Multicomponent platinum-free nanoporous Pd-based alloy as an active and methanol-tolerant electrocatalyst for the oxygen reduction reaction

Development of high-performance oxygen reduction reaction (ORR) catalysts is crucial to improve proton exchange membrane fuel cells. Herein, a multicomponent nanoporous PdCuTiAl (np-PdCuTiAl) electrocatalyst has been synthesized by a facile one-step dealloying strategy. The np-PdCuTiAl catalyst exhibits a three-dimensional bicontinuous interpenetrating ligament/channel structure with an ultrafine length scale of ~3.7 nm. The half-wave potential of np PdCuTiAl is 0.873 V vs. RHE, more positive than those of PdC (0.756 V vs. RHE) and PtC (0.864 V vs. RHE) catalysts. The np-PdCuTiAl alloy shows a 4-electron reaction pathway with similar Tafel slopes to PtC. Remarkably, the half-wave potential shows a negative shift of only 12 mV for np-PdCuTiAl in the presence of methanol, and this negative shift is much lower than those of the PdC (50 mV) and PtC (165 mV) catalysts. The enhanced ORR activity of np-PdCuTiAl has been further rationalized through density functional theory calculations.