Edge-segregated ternary Pd–Pt–Ni spiral nanosheets as high-performance bifunctional oxygen redox electrocatalysts for rechargeable zinc–air batteries

Abstract

Rational design of high-performance bifunctional electrocatalysts to simultaneously accelerate the sluggish reversible oxygen reduction and evolution reactions (ORR and OER) is an enormous challenge that restricts the working efficiency and rechargeable cyclability of metal–air batteries. Here we report a facile one-pot synthesis of edge-segregated trimetallic Pd–Pt–Ni spiral nanosheets (SpNSs) to serve as active dual-electrocatalysts toward ORR and OER electrocatalysis under alkaline conditions, showcasing a workable cathode electrocatalyst for high-performance and rechargeable zinc–air batteries (ZABs). These trimetallic SpNSs are generated from a template-directed, spiral dislocation growth process with the later deposited Pt–Ni active ingredient mainly segregated at the low-coordinated edges. Partial in situ oxidation of incorporated Ni generates highly dispersed NiO_x species which play a crucial role in modulating the electronic structure of Pd and Pt and providing strong hydroxyl adsorption sites. Owing to these merits, the Pd₄₅Pt₄₄Ni₁₁ SpNSs exhibit excellent ORR mass activity (4.90 A mg_Pd+Pt⁻¹) in 0.1 M KOH, which is 28.8 times that of commercial Pt/C. Meanwhile, they require a substantially lower overpotential than Pt/C and Ni-free counterparts to attain a current density of 10 mA cm⁻² for the reverse OER. When employed as the cathode in a practical ZAB, the Pd₄₅Pt₄₄Ni₁₁ SpNSs present greatly improved power density and rechargeability compared to the Pt/C benchmark. This work realizes atomic-level manipulation for the distribution of active ingredients on ultrathin 2D multimetallic nanostructures, offering a novel platform for the exploration of high-performance energy conversion heterocatalysts.