Co single atom loaded carbon nitride porous nanotube catalysts for efficient photothermal catalysis for H2O2 production

Abstract

To develop the efficient catalytic active sites for the reduction of O₂ to H₂O₂ while ensuring their inertness to H₂O₂ decomposition is crucial for the photothermal catalytic synthesis of H₂O₂ process, but still faces challenges. Herein, Co single-atom-loaded carbon nitride porous nanotubes (Co_SA/CN-PNTs) were prepared by self-assembled polymerization and calcined annealing. The Co single atom is not only Co single atom can not only form CoN bond with N in CN as an electron transport bridge, but also act as an active center in the photothermal catalytic O₂ reduction for H₂O₂ synthesis. The porous tubular structure not only contributes to the enhancement of light absorption and utilization, but also facilitates the adsorption of O₂ as well as the formation of the key intermediate *OOH on the Co sites. Notably, the thermal effect generated by Co_SA/CN-PNT during photocatalysis contributes to the rapidity of the reaction and ensures that the rapidly adsorbed O₂ on its surface inhibits the decomposition of H₂O₂. The results showed that the H₂O₂ generation rates of Co_SA/CN-PNT reached 148.6 μmol L⁻¹ h⁻¹ and 169.6 μmol L⁻¹ h⁻¹ under visible light and solar radiation irradiation, respectively, which were 15 times and 16 times higher than those of the pristine CN material by a factor of 15.1 and 13.9, respectively. Therefore, this work improves the construction and understanding of the structure-efficacy relationship of catalysts at the atomic level by exploring the role of single atoms in the coordination shell layer and developing catalytic centers with unique single atoms.