Bimetallic Center Metal–Organic Framework Catalysts for the Two-Electron Oxygen Reduction Reaction

Addressing the critical scientific challenge of enhancing the catalytic efficiency of transition metal-based metal–organic framework (MOF) materials in the two-electron oxygen reduction reaction (2e– ORR) for the electrochemical synthesis of H2O2 is of paramount importance in a related field. In this context, we had developed an interface synthetic strategy for constructing a series of bimetallic Ni–M (M = Co, Fe, Cu) center MOFs. This approach capitalized on the strong synergy among metallic ions, effectively regulating the electronic structure and thereby improving the catalytic activity of Ni active sites. Notably, the proposed Ni–Co MOF catalyst demonstrated exceptional 2e– ORR activity, achieving a remarkable H2O2 selectivity of up to 96%. This performance significantly surpassed that of Ni–Fe (54%) and Ni–Cu (67%) MOFs, as well as many other reported transition metal catalysts. Detailed studies on the structure–function relationship at the atomic level unveiled that Ni species in a high oxidation state, effectively regulated and stabilized by adjacent Co2+ ions, played a pivotal role in ensuring the superior 2e– ORR activity of the Ni–Co MOF. These physical-chemical insights into the reaction mechanism and structure–function relationships offer valuable guidance for the rational design of highly efficient MOF-based catalysts and reaction systems for on-site electrochemical synthesis of H2O2 via a 2e– ORR process.