PdPt alloy nanoparticles (NPs) are promising catalysts for various chemical reactions because of the presence of powerful catalytic components of Pt and Pd on the surface of one nanostructure. In this paper, we report a facile synthesis of polyhedral PdPt alloy NPs via coreduction of Pd(acac) 2 (acac = acetylacetonate) and Pt(acac) 2 with morpholine borane in oleylamine at 90 and 180 °C. In the synthesis, the molar ratio of the two metal precursors added in the reaction mixture was carried over to the final PdPt NP product, and compositions of the PdPt NPs were readily tuned from Pd 88 Pt 12 to Pd 34 Pt 66 . These PdPt NPs show the composition-dependent catalytic activity for methanol oxidation, with NPs in 40À60 atomic % Pt exhibiting the superior activity and durability.

Electronic devices process information and transduce energy with electrons, while biology performs such operations with ions and chemicals. To establish bio‐device connectivity, we fabricate a redox‐capacitor film from a polysaccharide (i.e., chitosan) and a redox‐active catechol. We report that these films are rapidly and repeatedly charged and discharged electrochemically via a redox‐cycling mechanism in which mediators shuttle electrons between the electrode and film (capacitance ≈ 40 F/g or 2.9 mF/cm2). Further, charging and discharging can be executed under bio‐relevant conditions. Enzymatic‐charging is achieved by electron‐transfer from glucose to the film via an NADPH‐mediated redox‐cycling mechanism. Discharging occurs by electron‐donation to O2 to generate H2O2 that serves as substrate for peroxidase‐mediated biochemical reactions. Thus, these films offer the capability of inter‐converting electrochemical and biochemical inputs/outputs. Among potential applications, we anticipate that catechol–chitosan redox‐capacitor films could serve as circuit elements for molecular logic operations or for transducing bio‐based chemical energy into electricity.

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