Stoichiometry-governed interfacial synergy in a multi-dimensional Ni-Mo_xC heterostructure for efficient H₂O₂...

The electrochemical synthesis of hydrogen peroxide via the two-electron oxygen reduction reaction (2e^- ORR) represents a sustainable alternative to the energy-intensive anthraquinone process. Its viability hinges on developing cost-effective catalysts with high activity and selectivity. Here, we report a rationally designed multi-dimensional heterostructure Ni-Mo_xC, composed of zero-dimensional Ni and Mo_xC nanoparticles and two-dimensional carbon sheets. By systematically tuning the Mo/Ni atomic ratio, we identify a volcano-type dependence of the 2e^- ORR performance on catalyst composition. The optimal Ni-Mo_xC-10 catalyst exhibits exceptional selectivity for H₂O₂ (>93%) and remarkable stability over 27 hours of operation. Mechanistic investigations reveal that the performance apex arises from a synergistic interfacial effect induced by the precise stoichiometry. The optimal Mo/Ni ratio maximizes the formation of an active Ni-Mo_xC heterointerface, which collectively optimizes the adsorption energy of the *OOH intermediate, suppresses H₂O₂ decomposition, and facilitates rapid proton/electron transfer. This work highlights the critical role of compositional tuning in maximizing interfacial synergy within complex heterostructures, providing a guiding principle for the design of advanced electrocatalysts for on-demand H₂O₂ production.