Dual MOF-derived porous carbon composites: Preparation of efficient bifunctional catalysts by pyrolytic protection strategy

Following the "MOF-protected pyrolysis" strategy, a dense carbon shell derived from ZIF tightly encapsulated MIL-53(Fe) during pyrolysis. This approach effectively prevented the high-temperature collapse of MIL-53 pore walls, thereby constructing a robust "MIL-53-carbon skeleton" composite. Furthermore, cetyltrimethylammonium bromide (CTAB) was introduced to regulate ZIF crystal growth and tailor the microporous structure. Ultimately, this process yielded nanoscale dual-MOF hybrid materials, which thus exhibit outstanding activity for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). In alkaline media, its ORR half-wave potential (E 1/2  = 0.926 V) significantly surpasses that of commercial Pt/C (E 1/2  = 0.826 V). For OER, the overpotential required to reach 10 mA cm −2 (η = 349 mV) is lower than that of RuO 2 (η = 368 mV). The ORR/OER potential gap (ΔE = E j10 - E 1/2 ) is only 0.653 V, which is narrower than that of the Pt/C + RuO 2 mixture (m:m = 1:1, ΔE = 0.772 V) under the same conditions. The optimally prepared composite also demonstrated excellent performance in assembled zinc-air batteries, offering a promising strategy for designing efficient bifunctional electrocatalysts.