Single Pt Atom with Highly Vacant d-Orbital for Accelerating Photocatalytic H₂ Evolution

Modulating the electronic structure of cocatalysts is critical for designing active sites toward efficient photocatalytic H2 evolution. Here, we report an electronic modulation in atomically dispersed Pt as highly efficient H2-evolution sites on graphitic carbon nitride (g-C3N4) nanosheets. Synchrotron radiation X-ray spectroscopic results confirm the singly dispersed Pt atoms anchored on g-C3N4 via forming “Pt1–N4” moiety, where the strong interaction of Pt with supports leads to the redistribution of Pt valence electrons with the highly vacant 5d orbital. Mechanistic investigations reveal that the immobilization of Pt single atoms with electron-deficient 5d orbitals on g-C3N4 nanosheets not only facilitate the separation of electron–holes pair but also optimize the water reduction kinetics on the surface. As a result, the Pt single atoms photocatalyst achieves a high intrinsic activity with turnover frequency of 250 h–1, about 13 times higher than the 19.5 h–1 of its nanocrystal counterpart.