Molecular-level insights on NIR-driven photocatalytic H2 generation with ultrathin porous S-doped g-C3N4 nanosheets

Unraveling how mid-gap state energy level of graphitic carbon nitride (g-C3N4) promote near-infrared (NIR) driven photochemical energy conversion at the molecular level remains a grand challenge. Here, we report a series of S double-site-doped ultrathin g-C3N4 nanosheets (SUCN) with adjustable intermediate band gap benefits from light response over NIR region. The SUCN produced after optimizing S double-site doping can effectively generate hydrogen (H2) under NIR-light irradiation. The highest H2 generation rate achieved was respectively 9.35 and 17.46 μmol g−1 h−1 under λ = 765 and λ > 800 nm, which is firstly expended photocatalytic activity of S-doped g-C3N4 to NIR region beyond λ > 765 nm. We proposed a molecular-level method, i.e., the localized oxidation state of proton acceptor triethanolamine (TEOA) in the mid-gap state to ensure the NIR-driven H2 generating behavior.