Graphitic Carbon Nitrides as Platforms for Single-Atom Photocatalysis
Herein we demonstrate that adding single-atoms of selected transition metals to graphitic carbon nitrides allow the tailoring of their electronic and chemical properties of these 2D nanomaterials, directly impacting their usage in photocatalysis. These single-atoms photocatalysts were successfully prepared with Ni2+, Pt2+ or Ru3+ by cation exchange, using poly(heptazine imides) (PHI) as the 2D layered platform. Differences in photocatalytic performance for these metals were assessed using rhodamine-B (RhB) and methyl orange (MO) as model compounds for degradation. We have demonstrated that single-atoms may either improve or impair the degradation of RhB and MO depending on the proper matching of the net charge of these molecules and the surface potential of the catalyst, which in turn is responsive to the metal incorporated into the PHI nanostructures. Computer simulations demonstrated that even one transition metal cation causes dramatic changes in the electronic structure of PHI, especially regarding light absorption, which was extended all along the visible up to the near IR region. Besides introducing new quantum states, the metal atoms strongly polarized the molecular orbitals across the PHI and electrostatic fields arising from the electronic transitions have become at least tenfold stronger. This simple proof of concept demonstrates that these new materials hold promise as tools for many important photocatalytic reactions, which are strongly dependent on our ability to control surface charge and it polarization under illumination, such as H2 evolution, CO2 reduction and photooxidations in general.
- This article is part of the themed collection: Chemistry of 2-dimensional materials: beyond graphene