Atomically Dispersed ZnN₄ Sites Anchored on P-Functionalized Carbon with Hierarchically Ordered Porous Structures for...

Tuning the coordination structures of metal sites is intensively studied to improve the performances of single-atom site catalysts (SASC). However, the pore structure of SASC, which is highly related to the accessibility of active sites, has received little attention. In this work, single-atom ZnN₄ sites embedded in P-functionalized carbon with hollow-wall and 3D ordered macroporous structure (denoted as H-3DOM-ZnN₄ /P-C) are constructed. The creation of hollow walls in ordered macroporous structures can largely increase the external surface area to expose more active sites. The introduction of adjacent P atoms can optimize the electronic structure of ZnN₄ sites through long-rang regulation to enhance the intrinsic activity and selectivity. In the electrochemical CO₂ reduction reaction, H-3DOM-ZnN₄ /P-C exhibits high CO Faradaic efficiency over 90% in a wide potential window (500 mV) and a large turnover frequency up to 7.8 × 10⁴  h^-1 at -1.0 V versus reversible hydrogen electrode, much higher than its counterparts without the hierarchically ordered structure or P-functionalization.