Understanding the injection process of hydrogen on Pt1-TiO2 surface for photocatalytic hydrogen evolution

Observing and understanding the surface changes of catalysts during reactive process can provide imperative insights into the mechanism study. Here, we investigated several different surface behaviors based on Pt/TiO2 catalysts during photocatalytic hydrogen evolution process. We found the single Pt atoms on TiO2 surface (Pt1-TiO2) could induce the hydrogen injection into the TiO2 subsurface to generate self-hydrogenated shell. This hydrogenated configurations in subsurface can serve as dominated locations for hydrogen formation and desorption process, which greatly boost the catalytic rate. Electron energy loss spectroscopy and in-situ experiments further confirm the as-formed amorphous shell contains reduced Ti ions and oxygen defects. Density functional theory calculations verify that high-concentrated hydrogenated shell on Pt1-TiO2 surface can significantly reduce the desorption energies of H2 formation. Our discovery thus provides important insight for the fundamental understanding of hydrogen evolution reactions and is also expected to open up a new way to design highly effective photocatalysts.