Unraveling the Microstructure-Property Relationship of Fe Single-Atoms via Introducing Asymmetric P-Coordination for Photocatalytic Hydrogen Evolution

Abstract

The local atomic environments of single-atom photocatalysts play a decisive role in determining the solar-to-hydrogen energy conversion efficiency. However, controllably modulating the microstructure of single-atom sites to enhance catalytic activity and deeply understanding the structure-property relationship remain great challenges. Herein, electron-rich P atoms are introduced to accurately regulate the local coordination environment and electronic configuration of Fe single atoms and construct a unique asymmetrical FeN3P2 motif into carbon nitride (FeN3P2-CN) for significantly improving the photocatalytic H2 evolution activity and stability. Specifically, in the absence of noble metal cocatalyst and photosensitizer, the FeN3P2-CN achieves a remarkable H2 evolution rate of 2668.5 µmol g−1 h−1 under visible light irradiation (λ > 420 nm), more than 105 times higher than that of unregulated FeN4 sample. Systematic characterizations and theoretical calculations unveil that the FeN3P2 single-atom sites not only significantly broaden the photoabsorption region and facilitate the charge separation and interfacial transfer, but also efficiently promote adsorption and activation of H2O. This work paves a promising pathway to design novel single-atom photocatalysts at the atomic level for achieving highly efficient water-splitting performance.