Photochemical Construction Of Nitrogen-Containing Nanocarbons For Carbon Dioxide Photoreduction

The solar-driven reduction of carbon dioxide (CO2) using nonmetal catalysts is an appealing solution to address the current energy and environmental challenges. Herein, we synthesized nitrogen-containing nanocarbons (NCNs) with a nitrogen content of 27.6 atom % by a photochemical approach. We found that this NCNs structure can act as a catalyst to drive the reduction of CO2 into carbon monoxide (CO). The CO evolution activity over the NCNs reached 34.5 mu mol/30 min (1 mg NCN) with a selectivity of 80.4%. The quantum efficiency over the NCNs was 2.3% at 450 nm irradiation, which is comparable to those of the metal-based catalysts for CO2 reduction under visible light irradiation. The reaction processes of CO2 reduction were investigated by CO2 adsorption, CO2 temperature-programmed desorption, and in situ diffuse reflectance infrared Fourier transform spectroscopy. Results suggested that the pyridinic nitrogen sites within NCNs were the main active species for CO2 reduction catalysis. Besides, we observed that nanocarbons with oxygen modification can also drive the CO2 reduction reaction. However, the promotion effect of the nitrogen modification on CO2 reduction was better than that of the oxygen modification on CO2 reduction. Additionally, using this photochemical approach, we synthesized different nanocarbons by changing carbon precursors, highlighting the versatility of this approach. This work expands the application of nanocarbon for photosynthetic CO2 conversion.