Ag3PO4/g-C3N4 nanocomposites for photocatalytic degradating gas phase formaldehyde at continuous flow under 420 nm LED irradiation

A series of Ag3PO4/g-C3N4 nanocomposites were synthesized by introducing various small amount of Ag3PO4 in g-C3N4 and subsequently employed for decomposing formaldehyde (HCHO) in continuous flow as photocatalysts. The results show that all the Ag3PO4/g-C3N4 nanocomposites could perform a very stable photoactivity for degrading continuously flowing gaseous formaldehyde for at least 600 h. Especially, the HCHO degradation rate reached 22.4% by using 1AP-CN, which was 2.63 times as fast as that of g-C3N4. Our results reveal that the photoinduced electrons in conduction band (CB) are trapped by O2 to yield ⋅O2−, while holes in valence band (VB) directly oxidize –OH and/or water to produce ·OH under visible light irradiation. As a consequence, HCHO is further oxidized to CO2 and H2O by as-generate active species.