Engineering electronic interaction between cobalt single atom and polymeric carbon nitride for hydrogen peroxide...

Polymeric carbon nitride (PCN) was extensively employed as a promising candidate in fields of hydrogen peroxide (H₂O₂) photosynthesis due to its eco-friendliness and chemical stability. Herein, a photocatalyst of cobalt single atom (Co SA) anchored PCN (Co-PCN) was synthesized via hydrothermal-calcination combined approach. Under light irradiation, the H₂O₂ production rate of optimal Co-PCN-20 reached 1632 μmol/g/h, surpassing 5.9-folds than that of pristine PCN (276 μmol/g/h). In-situ XPS spectra was tested to confirm Co SA will obtain electrons from the PCN support and then act as an electron reservoir to provide more active sites. Characterization results demonstrated that the incorporation of Co SA can broaden light absorption range, induce lower bandgap and further accelerate the separation and migration efficiency of photoinduced charges when compared with the pristine PCN. In addition, DFT calculation results revealed oxygen adsorption and activation ability on Co-PCN was greatly improved by adjusting the electronic interaction between Co SA and PCN components, thus enhancing the Gibbs free energy during the ORR process. Ultimately, the proposed reaction pathways in H₂O₂ production was adequately verified via in-situ DRIFTS investigation. This work strenuously introduces an efficient strategy for designing single atom reinforced PCN-based photocatalysts and crucially establishes a photocatalytic criterion for developing energy conservation and emission reduction systems for H₂O₂ artificial photosynthesis.