Application of photocatalytic degradation of formaldehyde by g-C 3 N 4 -Ag/SiO 2 heterostructure composites

Composite photocatalytic materials were synthesized by liquid-phase ultrasonic exfoliation-photochemical deposition method-impregnation method of monolithic silver (Ag), thin layer of graphitic phase carbon nitride (g-C3N4) and silica-alumina colloidal spheres (SiO2). A formaldehyde degradation hermetic chamber was designed to investigate the photocatalytic properties of g-C3N4, Ag/g-C3N4 and g-C3N4-Ag/SiO2 (SAG) materials and their degradation effects on formaldehyde. The results show that the efficiency of degradation of formaldehyde can reach up to 65.6% for SAG materials under visible light source conditions. 40% relative humidity can effectively enhance the degradation efficiency.The formaldehyde degradation efficiency decreases by only 9.71% when the silica-alumina spheres load with 30 mg 4% Ag/g-C3N4 are recycled for 16 times. The results of material characterization, show that the visible light absorption intensity and absorption range of the material are enhanced by ultrasonic stripping and the introduction of Ag, and the separation of photogenerated electrons and holes are effectively promoted, which effectively enhance the degradation efficiency of formaldehyde molecules. The results show that the SAG material has excellent stability and good photocatalytic performance, which provides a better scientific basis for the application of practical organic pollutant treatment.