The semiconductor-mediated solar-driven the conversion of CO2 into the value-added fuels is considered as an ideal strategy for sustainable development. However, conventional semiconductors usually suffer from unsatisfactory photocatalytic performance due to the low efficiency of photo-induced carrier separation and sluggish interface adsorption/desorption equilibrium of reactants/products. Herein, novel carbonized polymer dots (CPDs)/PbBiO2Br heterojunction photocatalysts have been prepared via self-sacrificing ionic liquid, which not only act as the template and reactant to induce the formation of PbBiO2Br material, but also act as the glue to in situ anchor CPDs on the surface of PbBiO2Br material to form composites through hydrogen bond. Without sacrificial reagent, the obtained CPDs/PbBiO2Br materials synthesized with ionic liquid exhibit a high selectivity, stability and enhanced CO evolution rate in water. The introduction of CPDs not only effectively promote the light absorbance and separation efficiency of photogenerated electrons, but also adjust the adsorption/desorption equilibria of reactants/products on the CPDs/PbBiO2Br catalyst surface, such as boosting CO2 adsorption capacity, proton affinity and CO liberation. The reaction mechanism has been proposed with in situ FT-IR spectrometry. The strategy for the preparation of high-performance CO2 photoreduction catalysts can be extended to design and tune other advanced photocatalytic materials.