Br-doped Bi2O2CO3 nanosheets with improved electronic structure and accelerated charge migration for outstanding photocatalytic behavior

The work presents a combinative merit of non-metal ion doping and active facet effect of Bi2O2CO3 photocatalyst. Br-doped Bi2O2CO3 nanosheets with exposed {0 0 1} facets were facilely prepared via a one-step hydrothermal reaction with the assistance of cetyltrimethylammonium bromide (CTAB) at a mild temperature of 60 °C for 4 h. The presence of CTAB not only influences the growth of Bi2O2CO3 crystalline but also leads to a Br-doping. Based on the crystal structure and DFT calculation, bromine from CTAB as dopant interstitially incorporates into Bi2O2CO3 lattice, which alters the band gap positions of Bi2O2CO3 and generates delocalized impurity states at the Fermi level. The improved electronic structure endows Br-doped Bi2O2CO3 with a broadened light-harvesting and accelarated charge migration. In addition, the thin nanosheet means more exposure of {0 0 1} active facets and larger internal electric field, which would also benefit for the charge separation. The sample with a trace Br content of 1.17 wt% shows the best degradation efficiency for RhB with a rate constant k enhanced by 3.6 folds compared with that of pure Bi2O2CO3 under simulated solar irradiation. Combining the effective catalytic sites and the detected active species, a possible migration mechanism of photogenerated e−/h+ pairs on the surface of Br-doped Bi2O2CO3 nanosheet is proposed. The work provides some new insights into the rational design and synthesis of non-metal doped semiconductor photocatalyst with facet dependency.