Enhanced Photocatalytic CO2 Reduction via CCH/g-C3N4 Heterojunction: Optimizing Charge Carrier Dynamics and Visible-Light Utilization

The photocatalytic CO2reduction (PCR) into value-added fuels offers a promising solution to energy shortages and the greenhouse effect, thanks to the mild conditions and environmental sustainability. However, the activation of CO2is challenging because of the thermodynamic stability and chemical inertness of CO2molecules, which significantly restricts the efficiency of PCR. Cobalt carbonate hexahydrate (CCH), known for its excellent CO2adsorption and activation properties, faces challenges like poor electron–hole separation and photoresponse. To address these issues, graphitic carbon nitride (CN) as a “pseudo-sensitizer” was introduced into the system by an in situ heterojunction synthesis strategy to produce CCH/CN photocatalyst, where Co–N bonds formed between CCH and CN enhance charge carrier migration and lower interfacial resistance. The CCH/CN catalyst achieved a CO production rate of 19.65 μmol g−1h−1, outperforming CCH, CN, and a mechanically mixed sample (Mix) by 7.74, 2.31, and 1.77 times, respectively. This work demonstrates an effective strategy for designing heterojunction catalysts to improve visible light utilization and charge transfer for efficient CO2reduction.