Ultrahigh Performance H O Generation by Single-Atom Fe Catalysts with N/O Bidentate Ligand via Oxalic Acid and Oxygen Molecules Activation.

Single-atom catalysts (SACs) for photocatalytic hydrogen peroxide (H O ) generation are researched but it is still challenging to obtain high H O yields. Herein, graphite carbon nitride (Fe /CN) confined single Fe atoms with N/O coordination is prepared, and Fe /CN shows high H O production via oxalic acid and O activation. Under visible light illumination, the concentration of H O generated by Fe /CN can achieve 40.19 mM g h , which is 10.44 times higher than that of g-C N . The enhanced H O generation can be attributed to the formation of metal-organic complexes and rapid electron transfer. Moreover, the O activation of photocatalysts is revealed by 3,3',5,5'-tetramethylbenzidine oxidation. The results display that the O activation capacity of Fe /CN is higher than that of g-C N , which facilitates the formation of H O . Finally, density functional theory calculation demonstrates that O is chemically adsorbed on Fe atomic sites. The adsorption energy of O is enhanced from -0.555 to -1.497 eV, and the bond length of OO is extended from 1.235 to 1.292 Å. These results exhibit that the confinement of single Fe atoms can promote O adsorption and activation. Finally, the photocatalytic mechanism is elaborated, which provides a deep understanding for SACs-catalyzed H O generation.