Exploring new zeolitic imidazolate frameworks (ZIFs) with specific topologies and pore structures is important for extending applications and improving performances. In this work, a new farfalle-shaped ZIF with an ordered hierarchical structure (named ZIF-F) was easily built with zinc acetate and 2-methylimidazole (MeIm) in an aqueous system at room temperature. The synthesis mechanism of ZIF-F is a dual-induction interaction of a solvent and zinc source based on the synthesis protocol of ZIF-8. The prepared ZIF-F is a 3–5 μm dispersible particle constructed from numerous nanoplates with the same building units as ZIF-8. ZIF-F has a rich 4 nm inter-particle spacing with a 0.1074 cm3 g−1 total pore volume and exhibits high thermo- and solvent stability. It is worth noting that crystal transformation could occur from ZIF-F to ZIF-8 in methanol via the dissolution-recrystallization route. Regarding the adsorption of Congo red (CR), ZIF-F exhibits better adsorption capacity (182.82 mg g−1) than ZIF-8 (149.25 mg g−1) with 6 times higher adsorption rate than that of ZIF-8 because of the positive effect of its larger pore size and hierarchical structure.
The high-cost synthesis of highly dispersed non-noble metal–nitrogen–carbon (MNC) electrocatalysts hinders their practical applications. Here, we have developed a cost/time-efficient synthesis method for MNC electrocatalysts with highly dispersed metal sites, using the commercially available cheap ZnO as the Zn source, reducing the cost of Zn usage by over 80%. Our specially chosen solvent formamide can react with ZnO and allow the formation of nano-sized ZnFeCo–Nx complexes uniformly distributed in the formamide-derived high-N-doped carbon substrate. Further annealing the ZnFeCo–N–C precursor will produce a highly dispersed FeCo–NC target product. Electrochemical measurements show that the prepared FeCo–NC is an excellent electrocatalyst for alkaline oxygen reduction reaction (ORR), rendering superior onset and half-wave potentials of 1.05 and 0.92 V, respectively. The Al–air battery assembled using this also shows a high specific power (204.9 mW cm−2) and a large specific capacity (552 mA h g−1 at 10 mA cm−2), exceeding those of the 20 wt% Pt/C catalyst. Our method may inspire the scalable and low-cost production of highly dispersed MNC electrocatalysts and their wide range of practical applications.
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