Tailoring ultra-small ZnO nanoparticles through cobalt doping to enhance photocatalytic CO2 reduction†

Photocatalytic CO₂ reduction offers a promising pathway for achieving sustainable development. However, the effectiveness of this method faces challenges related to imbalanced charge transfer/utilization. To address these issues, this paper reports on cobalt-doped zinc oxide nanoparticles (Co-ZnO NPs). The cobalt doping not only increases light absorption but also improves charge transfer/separation kinetics and modulates the reduction reaction dynamics. Notably, photocatalytic tests show that cobalt-doped zinc oxide (Co-ZnO) achieves a CO yield of 143.90 μmol g⁻¹ h⁻¹, which is 15.73 times higher than that of undoped ZnO, and exhibits excellent stability. This study emphasizes the importance of polarization states induced by doping for achieving efficient charge separation, providing a new approach to enhance the efficiency of photoredox catalysis.