A Ni or Co single atom anchored conjugated microporous polymer for high-performance photocatalytic hydrogen evolution

The fabrication of single atom photocatalysts via a simple pathway is a crucial challenge to enable efficient production of hydrogen. Herein, we demonstrate a gaseous diffusion strategy to construct single atom photocatalysts by using the intrinsic nanopore of a pyridyl-functionalized conjugated microporous polymer (PCMP) to host nickel (Ni) or cobalt (Co) atoms. Comprehensive microscopy and spectroscopy characterization studies were carried out to understand the morphology and structure variations of the Ni or Co single atom anchored PCMP as photocatalysts. The experimental results show that Ni or Co is present as single atom anchored with pyridyl nitrogen, which prominently alters the electronic structures of the PCMP and delocalizes the charge density of the metal atom to promote proton adsorption. The outcome of the single atom anchoring substantially reduces the energy barrier of photocatalytic water splitting. As a result, Ni or Co single atom photocatalysts exhibit efficient hydrogen evolution performance with a rate of 1.72 mmol g(-1) h(-1) (AQE = 2.05% at 420 nm) under visible-light irradiation compared to pure PCMP. Moreover, the photocatalysts show excellent stability with negligible decreases in the rate of hydrogen evolution upon long-term cycling (25 h). Our findings offer a rational way for the engineering of single atom photocatalysts for energy and environment-related applications.