Steering sp-Carbon Content in Graphdiynes for Enhanced Two-Electron Oxygen Reduction to Hydrogen Peroxide

Compared to sp²-hybridized graphene, graphdiynes (GDYs) composed of sp and sp² carbon are highly promising as efficient catalysts for electrocatalytic oxygen reduction into oxygen peroxide because of the high catalytic reactivity of the electron-rich sp-carbon atoms. The desired catalytic capacity of GDY, such as catalytic selectivity and efficiency, can theoretically be achieved by strategically steering the sp-carbon contents or the topological arrangement of the acetylenic linkages and aromatic bonds. Herein, we successfully tuned the electrocatalytic activity of GDYs by regulating the sp-to-sp² carbon ratios with different organic monomer precursors. As the active sp-carbon atoms possess electron-sufficient π orbitals, they can donate electrons to the lowest unoccupied molecular orbital (LUMO) orbitals of O₂ molecules and initiate subsequent O₂ reduction, GDY with the high sp-carbon content of 50 at % exhibits excellent capability of catalyzing O₂ reduction into H₂O₂. It demonstrates exceptional H₂O₂ selectivity of over 95.0 % and impressive performance in practical H₂O₂ production, Faraday efficiency (FE) exceeding 99.0 %, and a yield of 83.3 nmol s^-1 cm^-2. Our work holds significant importance in effectively steering the inherent properties of GDYs by purposefully adjusting the sp-to-sp² carbon ratio and highlights their immense potential for research and applications in catalysis and other fields.