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Keywords:

  • alloys;
  • electrochemistry;
  • electron microscopy;
  • fuel cells;
  • nanostructures

Abstract

A nanoporous PdTi (NP-PdTi) alloy with uniform ligament size and controllable bimetallic ratio was easily fabricated by a one-step mild dealloying process of PdTiAl (precursor alloy). NP-PdTi consisted of an interconnected network of nanoscale ligaments with bicontinuous hollow channels extending in all three dimensions. Electrocatalytic measurements indicated that NP-PdTi had superior electrocatalytic activity in the oxygen reduction reaction (ORR) with enhanced specific and mass activities as well higher methanol tolerance relative to Pt/C. Interestingly, NP-PdTi showed higher catalytic durability than Pt/C with a lower decrease in the ORR activity and electrochemical surface area of the metal upon 5000 potential cycles in an acidic solution. DFT calculations demonstrated that alloying Pd with Ti could bring favorable electronic perturbation with the downshifted d-band center of Pd, leading to a weakened Pd[BOND]O bond and improved ORR performance. The excellent electrocatalytic performance in ORR renders NP-PdTi alloys attractive as efficient cathode electrocatalysts in fuel-cell-related technologies.