Boron-doped ultrathin BiOBr nanosheet promotion for photocatalytic reduction of CO2 into CO

Photocatalytic CO2 conversion into high value-added chemical products has attracted extensive attention from researchers. Nevertheless, photocatalysts still face numerous challenges, such as low efficiency and poor stability under visible light irradiation. In this paper, boron (B)-doped bismuth bromide (BiOBr) nanosheets are synthesized through one-step hydrothermal method by controlling the mole ratio of boric acid and Bi(NO3)3·5 H2O. X-ray photoelectron spectroscopy patterns indicate that B is successfully introduced into the crystal lattice of BiOBr. The transmission electron microscopy results show that the doping of B does not affect the crystal structure and morphology of BiOBr but reduces the thickness and diameter of BiOBr, widens the light absorption region, promotes the generation of oxygen vacancies and increases the separation efficiency of photoinduced electron hole pairs. Among B-doped BiOBr, 0.5B/BiOBr displays excellent selectivity for the photoreduction of CO2 into CO. After 1 h of reaction, the yield rates of CO and CH4 reach 21.72 µmol g−1 h−1 and 2.24 µmol g−1 h−1, which are approximately 2.12 and 1.17 times that of BiOBr, respectively. After multiple cycles, the productivity of CO remains stable. The photocatalytic mechanism of CO2 conversion for B-BiOBr was discussed. This study provides a strategy for constructing highly efficient photocatalysts for CO2 reduction.