Embedding Group VIII Elements into a 2D Rigid pc-C₃N₂ Monolayer to Achieve Single-Atom Catalysts with Excellent OER...

Under DFT calculations, a systematic investigation is carried out to explore the structures and oxygen evolution reaction (OER) catalytic activities of a series of 2D single-atom catalyst (SAC) systems, which are constructed by doping the transition metal (TM) atoms in group VIII into the cavities of rigid phthalocyanine carbide (pc-C₃N₂). We can find that when Co, Rh, Ir and Ru atoms are doped in the small or large cavities of a pc-C₃N₂ monolayer, they can be used as high-activity centers of OER. All these four new TM@C₃N₂ nanostructures can exhibit very low overpotential values in the range of 0.33~0.48 V, even smaller than the state-of-the-art IrO₂ (0.56 V), which indicates considerably high OER catalytic activity. In particular, the Rh@C₃N₂ system can show the best OER performance, given that doped Rh atoms can uniformly serve as high-OER-active centers, regardless of the size of cavity. In addition, a detailed mechanism analysis was carried out. It is found that in these doped pc-C₃N₂ systems, the number of outer electrons, the periodic number of doped TM atoms and the size of the embedded cavity can be considered the key factors affecting the OER catalytic activity, and excellent OER catalytic performance can be achieved through their effective cooperation. These fascinating findings can be advantageous for realizing low-cost and high-performance SAC catalysts for OER in the near future.