Facile synthesis of hemin-based Fe-N-C catalyst by MgAl-LDH confinement effect for oxygen reduction reaction

Because oxygen reduction reaction (ORR) is vital in high-capacity energy conversion and storage systems such as metal-air batteries and fuel cells, developing high-performance, low-cost ORR catalysts is crucial. Hemin containing Fe-N-4 macrocycle is an inexpensive and readily available natural material widely present in animal blood. Herein, an efficient and environment-friendly method for preparing hemin-based carbon material is proposed based on the characteristic of the flexible interlayer space of layered double hydroxides (LDH). Hemin (Hm) was initially intercalated into the interlayer region of LDH. Subsequently, high-temperature carbonization was used to prepare Hm-LDH-700, a material with a graphene-like 2D lamellar structure with high ORR catalytic activity. Characterization results showed that the material has a two-dimensional porous network structure and a large specific surface area (1065.79 m(2) g(-1)), which provides numerous active sites in the ORR reaction. Electrochemical tests revealed that Hm-LDH-700 exhibits greater ORR catalysis than Pt/C, with a higher half-wave potential (0.86 V vs. reversible hydrogen electrode (RHE)), a higher limiting current density (6.21 mA cm(-2)), and a lower Tafel slope (74 mV dec(-1)). This study presents a simple and effective strategy for preparing high-performance ORR hemin-based catalysts, which is crucial in the practical applications of sustainable clean energy.