Photocatalytic oxygen reduction provides a sustainable method for on-site hydrogen peroxide (H₂O₂) synthesis. However, most photocatalysts suffer from moderate kinetics due to sluggish electron transfer and inefficient oxygen adsorption and activation. Herein, sodium (Na) and potassium (K) are co-incorporated into graphitic carbon nitride (g-C₃N₄) via a stepwise co-doping strategy combining sodium chloride-induced and molten salt-assisted polymerization. Experimental results and density functional theory calculations demonstrate that the synergistic interaction between intralayer Na⁺ ions and interlayer K⁺ ions facilitates charge carrier separation and migration both within and between g-C₃N₄ layers. Additionally, multiple heteroatom sites enhance surface charge polarization and introduce cyano groups, which synergistically promote oxygen molecule (O₂) adsorption and elevate local proton coverage. Simultaneously, the energy barrier for H₂O₂ desorption on the optimal photocatalyst (5Na/3.3K-CN) is lowered, thus improving H₂O₂ production efficiency. Eventually, 5Na/3.3K-CN exhibits an impressive H₂O₂ yield of 2541.6 μmol·g⁻¹·h⁻¹ in an artificial reactor, which is 10.6 times higher than that of pure g-C₃N₄ (240.2 μmol·g⁻¹·h⁻¹). Under natural sunlight outdoors, 5Na/3.3K-CN still maintains ultrahigh H₂O₂ photosynthesis efficiency, achieving an H₂O₂ photosynthesis rate of 2068.7 μmol·g⁻¹·h⁻¹. This work introduces a straightforward method to simultaneously optimize charge transfer and O₂ activation for boosting H₂O₂ photosynthesis, offering valuable insights toward the real-world deployment of g-C₃N₄-based photocatalysts in environmental protection and energy conversion.

This study simulated the adsorption and separation of CO₂ by the metal-organic frameworks material M-MOF-74, established the skeleton model of M-MOF-74 series adsorbent, and calculated the adsorption of CO₂ pure component gas and CO₂/N₂ mixed gas on M-MOF-74 series adsorbent by the grand canonical Monte Carlo method. Among the CO₂ adsorption performances of MOF-74 materials with metal centers of Mg, Co, Ni, and Zn, Mg-MOF-74 had the highest CO₂ adsorption capacity, adsorption selection coefficient and adsorption heat. When mixed gas was adsorbed, the law of CO₂ adsorption was consistent with that of pure CO₂ adsorption. The size law of adsorption heat on MOF-74 was similar to that of adsorption amount. Our findings demonstrated that the interaction between the metal-organic framework material and CO₂ is greater than that between the material and N₂. The interaction between the gas and the MOF-74 series adsorbent was the main factor affecting the adsorption amount, which reveals the strong influence of metal central atoms on the amount of gas adsorption. Our findings provide new ideas for the design of efficient adsorbent materials.