Interface-rich Au-doped PdBi alloy nanochains as multifunctional oxygen reduction catalysts boost the power density and durability of a direct methanol fuel cell device

The development of cathode oxygen reduction reaction (ORR) catalysts with high characteristics for practical, direct methanol fuel cells (DMFCs) has continuously increased the attention of researchers. In this work, interface-rich Au-doped PdBi (PdBiAu) branched one-dimensional (1D) alloyed nanochains assembled by sub-6.5 nm particles have been prepared, exhibiting an ORR mass activity (MA) of 6.40 A·mg_Pd⁻¹ and long-term durability of 5,000 cycles in an alkaline medium. The MA of PdBiAu nanochains is 46 times and 80 times higher than that of commercial Pt/C (0.14 A·mg_Pt⁻¹) and Pd/C (0.08 A·mg_Pd⁻¹). The MA of binary PdBi nanochains also reaches 5.71 A·mg_Pd⁻¹. Notably, the PdBiAu nanochains exhibit high in-situ carbon monoxide poisoning resistance and high methanol tolerance. In actual DMFC device tests, the PdBiAu nanochains enhance power density of 140.1 mW·cm⁻² (in O₂)/112.4 mW·cm⁻² (in air) and durability compared with PdBi nanochains and Pt/C. The analysis of the structure–function relationship indicates that the enhanced performance of PdBiAu nanochains is attributed to integrated functions of surficial defect-rich 1D chain structure, improved charge transfer capability, downshift of the d-band center of Pd, as well as the synergistic effect derived from “Pd-Bi” and/or “Pd-Au” dual active sites.