Potassium/oxygen co-doped polymeric carbon nitride for enhanced photocatalytic CO2 reduction

Polymeric carbon nitride (CN) is a cheap and visible-light photocatalyst for potentially real application of CO2 photoreduction into solar fuels. However, CN prepared by conventional one-step method always shows serious charge recombination and low charge mobility. Herein, we use urea as the starting material with K2S2O8 to synthesize defect-modified ultrathin CN nanosheets. The as-prepared samples exhibit much higher photocatalytic CO2-reduction efficiency than the pristine CN with the production of CO and CH4 fuels. The enhanced photocatalytic activity of modified samples is ascribed to the co-doping of K and O atoms into the CN frameworks, which promotes electron transfer from the bulk to the interface and narrows the band gap to provide a broad range of visible-light response. This work provides a simple but effective strategy to prepare defect-modified polymeric carbon nitride for various photocatalytic applications.