Transforming Waste Biomass into N-Rich Carbon Dots with Built-In Active Sites for Efficient CO₂ Photoreduction from Flue Gas

The direct conversion of CO2 from simulated flue gas to chemical feedstock gases using solar energy remains a significant challenge. A fundamental difficulty is the design of catalyst surfaces with high CO2 affinity and the improvement of photocatalytic accumulation efficiency. Herein, we developed a facile synthesis strategy to prepare model anatase photocatalyst (Ti-EBCD) surface-functionalized with waste-biomass-derived carbon dot (EBCD) for CO2 conversion. Importantly, the abundant functional groups and intrinsically active pyridinic-N sites in Ti-EBCD construct a CO2-affinitive surface, thereby enhancing the CO2 adsorption and activation. The optimized Ti-EBCD catalyst not only achieves a tunable syngas conversion with pure CO2 but also exhibits high CO selectivity during simulated flue gas conversion. A series of characterizations, in situ experiments, and theoretical calculations were employed to establish structure–activity relationships and reveal the reaction mechanisms behind the enhanced selective conversion of simulated flue gas. We anticipate that this work will provide insights into the development of advanced surface-engineered photocatalysts for solar-driven simulated flue gas conversion.