Activation of strong n-π* transition by grafting abundant hydroxy group on pyridine doping ultrathin carbon nitride for NIR H2 production

The light harvesting property of organic photocatalysts relays on the conjugated framework and its circumjacent chemical circumstances. Herein, a step-by-step modified method is practiced to graft abundant hydroxy group on pyridine doping carbon nitride (PyCNS-x), which synchronously regulates the π-π* and n-π* transitions for wide-spectrum responsive. Beforehand, the pyridine is doped into the conjugated framework for the modification of conjugated structure. More operable carbon sites are formed, which are favorable in thermodynamics for the graft of hydroxy group. The high-temperature redox process not only induces the graft of abundant hydroxy group on pyridine doping carbon nitride. But also, an ultrathin nanosheet is formed for the acquisition of large specific surface area. Related measurements manifest that the sheet thickness of PyCNS-80 is 4 nm. Spectral tests confirm that the light response range of PyCNS-80 is up to near-infrared region. Moreover, there is a strong n-π* transition occurrence in PyCNS-80 that further enhances the light absorption from 500 nm to 750 nm. Finally, the hydrogen evolution activity of PyCNS-80 is up to 1887.7 μmol g −1 h −1 and exhibits a detectable number of 9.0 μmol g −1 h −1 under infrared light. Briefly, this work demonstrates a reference to deeply optimize the electron transition behaviors of organic photocatalyst by designing their chemical structure.