关键词: Ni掺杂Bi₄O₅Br₂, 超薄材料, 偶极矩, 极化电场, 光催化CO₂还原

Abstract:

The low efficiency of photogenerated carrier separation, and the poor adsorption and activation ability of CO₂ on the surface of photocatalyst were the key problems to limit the efficiency of photocatalytic CO₂ reduction. Hence, maximally accelerating the immigration of photogenerated charges d increasing the number of active sites are critical points to boost the overall performance of photocatalytic CO₂ reduction. However, it is still huge challenge. In this work, the Ni-doped ultrathin Bi₄O₅Br₂ nanosheets, which was successfully prepared by hydrothermal and ultrasonic chemical stripping methods, exhibited efficient photocatalytic conversion of CO₂ to CO. The results of experiments and theoretical calculations indicated that the doped Ni²⁺ significantly increased the crystal dipole moment of Bi₄O₅Br₂ in y direction (from 0 to 0.096 eÅ), which enhanced the polarized electric field strength inside Bi₄O₅Br₂, and further promoted the immigration of photogenerated carriers. Meanwhile, the ultrathin structure and doped Ni²⁺ synergistically increased the number of active sites, thereby promoting the adsorption and activation of CO₂ molecules, as evidenced by experimental and theoretical results collectively. As result, The CO yield was as high as 26.57 μmol g^-1 h^-1 for the prepared Ni-doped ultrathin Bi₄O₅Br₂ nanosheets under full spectrum light irradiation, which was 9.48 times that of Bi₄O₅Br₂. Therefore, it is of great scientific significance in this study to explore strategies to promote the separation of photogenerated carriers and enhance the adsorption and activation ability of CO₂ on the surface.

Key words: Ni-doped Bi₄O₅Br₂, Ultra-thin nanomaterial, Dipole moment, Polarized electric field, Photocatalytic CO₂ reduction