Molybdenum-doped ordered L1 0 -PdZn nanosheets for enhanced oxygen reduction electrocatalysis

[摘要] 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 L1 0 -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 L1 0 -Mo-PdZn NSs exhibit excellent ORR mass activity of 2.6 A mg Pd −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, L1 0 -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 L1 0 structure and Mo doping can raise the vacancy formation energy of Pd atom and thus promote the ORR stability.

[学科分类] 电力

[关键词] electrocatalysis;fuel cell;nanosheeets;oxygen reduction;Pd-based intermetallics