Highly wrinkled palladium nanosheets as advanced electrocatalysts for the oxygen reduction reaction in acidic medium

[Display omitted] •Highly wrinkled Pd nanosheets with compressive strain are successfully prepared.•Wrinkles on HW-PdNs reduce reaction barrier of the rate determining step of ORR.•HW-PdNs exhibit 26 mV more positive half-wave potential toward ORR than Pt/C.•HW-PdNs show much higher catalytic activity and stability toward ORR than Pt/C. Although great efforts have been devoted to developing Pd-based catalysts to take the place of Pt toward Oxygen reduction reaction (ORR) in acidic medium, the progress is notably slower than expected. In this work, highly wrinkled ultrathin Pd nanosheets are synthesized and further demonstrated as an advanced catalyst for ORR, holding higher catalytic activity, 26 mV more positive half-wave potential and better stability than the commercial Pt/C. Theoretical studies reveal that the compressive strain created from the wrinkles can crucially downshift d-band center of Pd to reduce the reaction barrier of the rate determining steps of ORR for fast kinetics. The modulated electronic structure of Pd by the introduction of wrinkles display a major role in improving the stability. This work offers a non-Pt, highly active, and stable catalyst for ORR by tailoring the geometric structure of Pd, while shedding a scientific light on the enhancement mechanism of a nanostructure on electrocatalytic activity and stability.