Hyper-dendritic PdZn nanocrystals as highly stable and efficient bifunctional electrocatalysts towards oxygen reduction and ethanol oxidation

Although attentions have been devoted to developing Pd-based bimetallic nanocrystals towards the electrocatalytic oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR), the engineering of efficient bifunctional electrocatalysts with high atomic utilization still faces big challenges. Herein, we reported a facile one-pot template-free route to fabricate three-dimension hyper-dendritic PdZn nanocrystals (HD-PdZn NCs) that regulated by gas mixtures of carbon monoxide and hydrogen. The developed catalysts acted as robust bifunctional electrocatalysts for cathodic ORR and anodic EOR. Specifically, the engineered HD-PdZn NCs not only displayed superior mass activity (MA, 0.461 A mg Pd -1 ) and specific activity (SA, 0.393 mA cm −2 ) at 0.9 V, which were 5.2 and 5.0 times of commercial Pt/C, respectively, but also showed enhanced stability with only 3% loss of MA after 10,000 cycles for ORR. Density functional theory (DFT) calculations revealed the Zn implantation could facilitate the reduction of OOH* to OH* on the surface of Pd during the ORR process. Moreover, HD-PdZn NCs exhibited the highest EOR mass activity with a value of 3.45 A mg Pd −1 among benchmarked catalysts in alkaline solution. The advantageous structural features and electron effects are proposed to be responsible for the remarkable bifunctional activities. This work illustrates a facile method to fabricate highly efficient bifunctional electrocatalyst for energy conversation application.