MnFe2O4 Nanocrystals Wrapped in a Porous Organic Polymer: A Designed Architecture for Water-Splitting Photocatalysis

A novel MnFe2O4–porous organic polymer (POP) nanocomposite was synthesized by a facile hydrothermal method and using the highly cross‐linked N‐rich benzene–benzylamine POP. The nanocomposite presented highly efficient photocatalytic performance in the hydrogen evolution reaction (HER) from pure water without addition of any sacrificial agent under one AM 1.5 G sunlight illumination. A photocatalytic activity of 6.12 mmol h−1 g−1 was achieved in the absence of any noble metal cocatalyst, which is the highest H2 production rate reported for nonprecious metal catalysts. The photocatalytic performance of MnFe2O4‐POP could be attributed to the intrinsic synergistic effects of manganese ferrite (MnFe2O4) nanoclusters interacting with the nitrogen dopant POP with a unique mesoporous nanoarchitecture and spatially confined growth of MnFe2O4 in the interconnected POP network, leading to high visible‐light absorption with fast electron transport. No noble metal cocatalyst required: A water‐splitting photocatalyst has been developed based on noble‐metal‐free MnFe2O4 nanocrystals and a porous organic polymer. The catalyst promotes the hydrogen evolution reaction (HER) from pure water without addition of any sacrificial agent.