B2-phase intermetallic palladium copper nanowires enable enhanced electrocatalysis

Abstract

Developing non-platinum materials with enhance performance for electrocatalytic reactions has been gaining attention in recently years. Palladium and Palladium-based materials are the most suitable candidates to substitute platinum catalysts in anodic and cathodic reactions due to their similar catalytic properties and higher abundancy than Pt materials. Herein, we report the synthesis of ultrathin palladium copper alloy nanowires (PdCu NWs) with an av. diam. of 5nm, followed by their transition process from alloy to intermetallic compd. in an electrochem. dealloying (leaching) method which allowed the rearrangement of Pd and Cu atoms to form intermetallic swelled tips and junctions denoted as *PdCu NWs that lead to a higher catalytic activity for hydrogen evolution reaction (HER) at low overpotentials. The synthesized alloy PdCu NWs presents a superior electrochem. surface area, and comparable catalytic activity for HER, overpotential and Tafel slope with that of com. Pt/C. On the other hand, the ordered counterpart *PdCu NWs intermetallic compd. exhibits a superior performance for HER in acidic and alk. media at lower overpotential, lower Tafel slope and higher ECSA if compared with their alloy counterpart, Pd NWs and com. Pt/C. Moreover, *PdCu nanowires presented higher mass activities during formic acid oxidn. reaction (FAOR) among all the materials studied and almost five times higher than com. Pd/C. In addn., *PdCu and PdCu alloy nanowires display superior stability for both reactions: HER in acid and basic conditions, and FAOR as well as good resistance against CO poisoning. To the best of our knowledge, the catalytic properties of our intermetallic *PdCu NWs for HER and FAOR are higher than their PdCu alloy counterpart, com. Pt/C, Pd/C, and those previously reported for 0D and 1D bimetallic nanostructures. Thus, the strategy presented in this work is helpful for future expansion to fabricate alloy and intermetallic nanowires based on noble metals combined with non-noble metals, and to continue exploring the synergetic properties when they are combined in a one-dimensional nanostructure. Moreover, this approach is an example of new routes for the development of multifunctional catalysts which encourage future investigations towards better options of catalysts at lower cost but still with high catalytic activity for diverse of electrochem. reactions.

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