Molybdenum‐doped ordered L10‐PdZn nanosheets for enhanced oxygen reduction electrocatalysis

Abstract

Abstract Ultrathin Pd‐based two‐dimensional (2D) nanosheets (NSs) with tunable physicochemical properties have emerged as promising candidate for oxygen reduction reaction (ORR). Unfortunately, structurally ordered Pd‐based NSs can be hardly prepared as high temperature annealing (>600°C) is necessary for disorder to order phase transition, making it a considerable challenge for morphology control. Herein, a new class of ultrathin structurally ordered Mo‐doped L10‐PdZn NSs with curved geometry and abundant defects/lattice distortions is reported as an efficient oxygen reduction electrocatalyst in alkaline solution. It is found that Mo(CO)6 serves as reducing agent and Mo source to generate the unique ordered 2D morphology, which leads to the significantly modified electronic structure. The developed L10‐Mo‐PdZn NSs exhibit excellent ORR mass activity of 2.6 A mgPd−1 at 0.9 V versus reversible hydrogen electrode, 31.5 and 17.6 times higher than those of Pd/C and Pt/C, respectively, outperforming most of the reported Pd‐based ORR electrocatalsyts. Impressively, L10‐Mo‐PdZn NSs is extremely stable for ORR, with only 2.3% activity loss after 10 000 potential cycles. Density functional theory study suggests that ordered L10 structure and Mo doping can raise the vacancy formation energy of Pd atom and thus promote the ORR stability.

Keywords

• electrocatalysis
• fuel cell
• nanosheeets
• oxygen reduction
• Pd‐based intermetallics