Structuring phase junction between tri-s-triazine and triazine crystalline C3N4 for efficient photocatalytic hydrogen evolution

Herein a novel carbon nitride composite with triazine-based crystalline carbon nitride (tri-C3N4) vertically aligned on tri-s-traizine-based crystalline carbon nitride (tri-s-tri-C3N4) is first proposed for efficient visible light driven (lambda > 420 nm) photocatalytic H-2 evolution. The well matched lattice fringes between (002) plane of tri-s-tri-C3N4 and (102) plane of tri-C3N4 characterized by TEM unambiguously demonstrate the successful construction of tight crystalline junction between tri-s-tri-C3N4 and tri-C3N4. As a result, the crystalline carbon nitride phase junction (tri-/tri-s-tri-C3N4) shows a high visible light photocatalytic H-2 evolution activity of 144 mu mol/h, which is 30 times higher than that of pristine g-C3N4. This outstanding photocatalytic H2 evolution performance could be attributed to the fact that the construction of crystalline tight junction can greatly enhance the transfer and separation efficiency of photoinduced carriers. This study may provide a new way for rational design of carbon nitride heterojunction for gaining high photocatalytic activity.