Pt2+-exchanged ZIF-8 nanocube as a solid-state precursor for L10-PtZn intermetallic nanoparticles embedded in a hollow carbon nanocage
Nanoparticles with an atomically ordered alloy phase have received enormous attention for application as catalysts in fuel cells because of their unique electronic properties arising from unusually strong d-orbital interactions between two metal components. However, the synthesis of intermetallic nanoparticles requires a high reaction temperature, thus necessitating the protection of nanoparticles with inorganic layers to prohibit aggregation of nanoparticles during synthesis. The protective layer later needs to be removed for application as a catalyst, which is a cumbersome process. Herein, novel synthetic strategy is reported for the preparation of L10-PtZn intermetallic nanoparticles by utilizing Pt2+-exchanged ZIF-8 nanocubes as a solid-state precursor. The Pt2+-exchanged ZIF-8 phase plays a dual role as the metal ion source for L10-PtZn nanoparticles and as a carbonaceous matrix that restrains the aggregation of nanoparticles during thermal treatment. The L10-PtZn nanoparticles embedded in a hollow carbon nanocage from one-step annealing of Pt2+-exchanged ZIF-8 showed better electrocatalytic activity and durability toward methanol oxidation under acidic electrolyte conditions than those of commercial Pt/C catalysts.