A Sucker-Reactor Polyoxometalate Assembled Superstructures for Efficient Photocatalytic Nitrogen Fixation

Designing a reaction system that integrates reactant capture and transformation in an artificial photosynthesis system to achieve high reaction efficiency remains challenging. Here, an ionic liquid (IL) -polyoxometalate (POM) superstructure photocatalyst (P2HPMo) is reported, where the anisotropy of the superstructure is allowed by adjusting the alkyl chain lengths of ILs. Experimental data and theoretical simulation show that ILs and POM serve as the “sucker” and “reactor” of the reaction system to capture and transform the reactants, respectively. In particular, the addition of quaternary phosphorous IL cations is not only conducive to the adsorption of N₂ but also effectively promotes the activation of N₂ by manipulating the energy band and electronic structure. Consequently, the synthesized P2HPMo exhibits an ammonia synthesis rate of 98 µmol·g_cat⁻¹·h⁻¹, which is one of the highest values available in a sacrificial agent-free system.