Polydopamine and Barbituric Acid Co-Modified Carbon Nitride Nanospheres for Highly Active and Selective Photocatalytic CO2 Reduction

Carbon nitride nanospheres modified with polydopamine and barbituric acid (BA-CNS-PDA) were successfully prepared by following a template-copolymerization and post-modification strategy. The photocatalytic CO2 reduction was carried out using BA-CNS-PDA as photocatalyst, Co(bpy)(3)(2+) as the cocatalyst and TEOA as the sacrificial electron donor. The productivity and selectivity for photocatalytic reduction of CO2 to CO on BA(20)-CNS-PDA(15) under visible-light for 4 h were measured to be 158 mu mol and 86.0 %, respectively, and are nearly 5 and 1.5 times, respectively, that of unmodified CNS. Optical characterization indicates that the outstanding photocatalytic CO2 reduction performance is a result of improved charge separation and transfer due to copolymerization with barbituric acid and enhanced visible light absorption due to polydopamine. The adsorption isotherm of CO2 demonstrates that polydopamine increase CO2 adsorption capacity and promote CO2 activation due to the presence of the amino groups.