Hierarchical Honeycomb Br-, N-Codoped TiO with Enhanced Visible-Light Photocatalytic H Production.

The halogen elements modification strategy of TiO encounters a bottleneck in visible-light H production. Herein, we have for the first time reported a hierarchical honeycomb Br-, N-codoped anatase TiO catalyst (HM-Br,N/TiO) with enhanced visible-light photocatalytic H production. During the synthesizing process, large amounts of meso-macroporous channels and TiO nanosheets were fabricated in massive TiO automatically, constructing the hierarchical honeycomb structure with large specific surface area (464 m g). cetyl trimethylammonium bromide and melamine played a key role in constructing the meso-macroporous channels. Additionally, HM-Br,N/TiO showed a high visible-light H production rate of 2247 μmol h g, which is far more higher than single Br- or N-doped TiO (0 or 63 μmol h g, respectively), thereby demonstrating the excellent synergistic effects of Br and N elements in H evolution. In HM-Br,N/TiO catalytic system, the codoped Br-N atoms could reduce the band gap of TiO to 2.88 eV and the holes on acceptor levels (N acceptor) can passivate the electrons on donor levels (Br donor), thereby preventing charge carriers recombination significantly. Furthermore, the proposed HM-Br,N/TiO fabrication strategy had a wide range of choices for N source (e.g., melamine, urea, and dicyandiamide) and it can be applied to other TiO materials (e.g., P25) as well, thereby implying its great potential application in visible-light H production. Finally, on the basis of experimental results, a possible photocatalytic H production mechanism for HM-Br,N/TiO was proposed.