Two-dimensional/two-dimensional heterojunction-induced accelerated charge transfer for photocatalytic hydrogen evolution over BiOBr/TiC: Electronic directional transport.

Regulating electron density at the active site by electronic directional transport from special channels is an effective strategy to accelerate the reaction rate in photocatalytic water splitting. Here, a novel two dimensional/two dimensional (2D/2D) BiOBr/TiC heterojunction with special interfacial charge transfer channel was fabricated successfully via in-situ growth of BiOBr on the surface of ultrathin TiC by using a convenient hydrolysis method. The electrostatic attraction between Bi cations and electronegative TiC ensures the construction of 2D/2D heterojunction and a strong intimate interface contact between TiC and BiOBr, which establishes an electronic transport channel, and shortens the charge transport distance, assuring excellent bulk-to-surface and interfacial charge transfer abilities. Meanwhile, X-ray photoemission spectroscopy (XPS) and density functional theory (DFT) calculation revealed that the local electron density at the TiC active sites is remarkably increased because of the transfer of interfacial electrons from BiOBr to TiC, which is a key factor for enhancing the photocatalytic performance. Thus, the resultant BiOBr/TiC exhibits significant improvement on the performance of photocatalytic hydrogen evolution under visible light irradiation. The hydrogen evolution reaction rate obtained on the optimized BiOBr/TiC composite is 1.97 times higher than that of pristine BiOBr. This work provides a new protocol for the construction of 2D/2D heterojunction photocatalytic systems and regulating electron density by electronic directional transporting.