Dipole moment regulation by Ni doping ultrathin Bi4O5Br2 for enhancing internal electric field toward efficient photocatalytic conversion of CO2 to CO

The low efficiency of photogenerated carrier separation, and the poor adsorption and activation ability of CO 2 on the surface of photocatalyst were the key problems to limit the efficiency of photocatalytic CO 2 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 CO 2 reduction. However, it is still huge challenge. In this work, the Ni-doped ultrathin Bi 4 O 5 Br 2 nanosheets , which was successfully prepared by hydrothermal and ultrasonic chemical stripping methods, exhibited efficient photocatalytic conversion of CO 2 to CO. The results of experiments and theoretical calculations indicated that the doped Ni 2+ significantly increased the crystal dipole moment of Bi 4 O 5 Br 2 in y direction (from 0 to 0.096 eÅ), which enhanced the polarized electric field strength inside Bi 4 O 5 Br 2 , and further promoted the immigration of photogenerated carriers. Meanwhile, the ultrathin structure and doped Ni 2+ synergistically increased the number of active sites, thereby promoting the adsorption and activation of CO 2 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 Bi 4 O 5 Br 2 nanosheets under full spectrum light irradiation , which was 9.48 times that of Bi 4 O 5 Br 2 . 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 CO 2 on the surface. In this study, the dipole moment of Ni-doped Bi 4 O 5 Br 2 is adjusted to enhance the intensity of the interlayer polarization electric field, so that the photogenerated carrier is easier to separate and transfer.