Reverse the Impact of Le Chatelier's Principle in Two-Electron Air Electroreduction.

Using high-purity oxygen (O) for electrofixation would increase the production cost of hydrogen peroxide (HO) because of requiring complex pre-treatment procedures. Atmospheric air is an abundant source, but the direct air electrofixation has proved to be very challenging, that in common conception against nitrogen (N) in the system. According to the Le Chatelier's principle, O concentration is diluted by N (78%) in atmospheric air, which reduces overall reaction rates/equilibrium. Here we report a catalyst system where the presence of N does not impose an adverse effect; rather, it is beneficial for activity. We combine both theoretical and experimental analyses to elucidate the underlying mechanisms, unlocking the critical function of electronic spin, arising from the strong synergy between iron oxide (FeO) and nickel-metal organic frameworks (Ni-MOF) that optimizes the activation of O in air. Consequently, the catalyst for direct air electrofixation has demonstrated an exceptional HO yield rate (262.6 mg h cm) and Faradaic efficiency (95.61%), outperforming its high-purity O counterpart (184.32 mg h cm and 67.06%). We expect the present findings providing an additional dimension to leverage systems beyond the constraint of traditional rules.