Amino-Functionalized Iron-Based Metal–Organic Frameworks Anchored on Aminated Carbon Nanotubes for Selective Two-Electron Oxygen Reduction Reaction toward Efficient H2O2 Electrosynthesis

The electrosynthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e– ORR) is a promising method with the advantages of safety, efficiency, and sustainability. However, the process is constrained by the low selectivity and catalytic activity of the catalysts. In this study, the amino-functionalized iron-based metal–organic frameworks anchored on aminated carbon nanotubes (Fe-BDC@CNT-NH2) are prepared as 2e– ORR catalysts to enhance H2O2 production. In this catalyst system: (1) carbon nanotubes (CNTs) were designed to improve the overall electron conductivity of the catalyst; (2) −NH2 groups in benzene-1,4-dicarboxylic acid (BDC) could modulate the intrinsic electron conductivity of metal–organic frameworks (MOFs); and (3) −NH2 groups on the CNT surface facilitated the anchoring and confinement of MOF growth by forming axial coordination structures (Fe–NO4). Smaller particles expose more active sites, while axial coordination structure enhances the adsorption capacity of Fe centers, effectively passivating Fe centers and optimizing the 2e– ORR performance at adjacent C sites. Thus, Fe-BDC@CNT-NH2 possesses high 2e– ORR selectivity and activity, under both alkaline and neutral conditions. For example, Fe-BDC@CNT-NH2 demonstrates a H2O2 average yield of 24 mol gcat–1 h–1 and maintains a Faraday efficiency (FE) > 80% over 12 h in alkaline. Against neutral conditions, it also exhibits approximately 84% selectivity and stability lasting up to 12 h. Especially, a large current of 1.0 A can be achieved under a 5 × 5 cm2 flow cell, thus endowing the electro-synthesized H2O2 with excellent dye degradation performance and broad application prospects.