Hollow Bi 4 O 5 Br 2 spheres enable high-density bismuth exposure for enhanced photocatalytic CO 2 -to-CO conversion

Hollow Bi₄O₅Br₂ spheres, featuring high-density bismuth exposure, are developed to enhance light absorption, charge separation and CO₂ activation, thus resulting in efficient photocatalytic CO₂-to-CO conversion performance, including a CO production rate of 13.31 µmol g^-1 h^-1, a selectivity of 85.9%, and sustained stability over 25 hours.