Iodine‐Manipulated Pt Single Atoms Bridged between Graphitic C₃N₄ Nanosheets for Boosted Photocatalytic Hydrogen Evolution

The platinum (Pt) single-atom site represents the limit of atomic utilization in Pt catalysis. In alkaline hydrogen evolution reaction (HER), slow water dissociation (Volmer step) and subsequent strong interactions between Pt and H atoms reduce the efficiency of H₂ desorption, resulting in an overall inefficient hydrogen evolution reaction. Addressing how to adjust the electronic structure of the Pt single-atom site to further enhance the catalytic efficiency remains a significant scientific challenge. Herein, a Pt single-atom photocatalysts with the Pt atoms confined within the interlayer of iodine (I)-doped graphitic carbon nitride (g-C₃N₄) has been fabricated by a ball-milling combined with a calcination strategy. Experiments and theoretical calculations demonstrate that interlayer single-atom Pt enables photoinduced electrons to shuttle through layers, resulting in fast interlayer charge transfer, the I-atom doping can enhance the light absorption capacity and electrical conductivity of the materials. Furthermore, the introduction of the I atoms increases the oxidation state of the Pt singe atoms between the g-C₃N₄ layers, promoting the dissociation of water, and the electronic state of the interaction between the I atom and the Pt atom is also conducive to H₂ desorption. Therefore, the proposed photocatalyst system provides exceptional photocatalytic alkaline HER performance. The hydrogen production rate at the stationary point is as high as 18.71 mmol g^-1 h^-1, and the apparent quantum yield at 420 nm is 36.93%. Notably, the hydrogen production rate in seawater remains high at 10.66 mmol g^-1 h^-1.