Construction of a micro–nano reactor assembled by TiO2/N–C ultrathin sheets for photocatalytic H2 evolution

In this paper, a series of micro-nano reactors assembled by N doped carbon coated TiO2 heterojunction nanosheets with different thickness, named TiO2/N-C hollow framework (HF), TiO2/N-C hollow hexahedron assembled by nanosheets (HHS), and TiO2/N-C hollow hexahedron assembled by ultrathin nanosheets (HHUS), have been prepared by adjusting the alcoholysis rate of NH2-MIL-125 and then pyrolysis. Experimental and theoretical studies revealed that with the decrease of the thickness of the heterojunction nanosheet subunit, more low-coordination Ti atoms would be exposed as effective sites for photocatalytic H2 evolution, and the interaction between the carbon layer and TiO2 would also be enhanced, which provided a smooth migration path for the effective separation of photogenerated carriers. Thus, TiO2/N-C HHUS with the thinnest nanosheet subunit exhibited the best photoelectric performance and the highest photocatalytic hydrogen production activity.