Constructing CeO2/nitrogen-doped carbon quantum dot/g-C3N4heterojunction photocatalysts for highly efficient visible light photocatalysis

Ternary CeO2/nitrogen-doped carbon quantum dot (NCQD)/graphitic carbon nitride (g-C3N4) heterojunction nanocomposites were prepared by a high-temperature calcination and hydrothermal method and tested for degrading tetracycline (TC) and generating H-2. Compared with CeO(2)and g-C3N4, theZ-scheme CeO2/NCQDs/g-C3N4(CSNx, wherexrepresents the amount of CeO(2)in wt%) nanoparticles showed a higher TC photodegradation capacity and H(2)evolution ability owing to enhanced efficient charge separation and photocatalytic stability. CSN5 showed the best photodegradation activity for TC degradation (100 mL, 20 mg L-1; 100% degradation in 60 min;lambda >= 420 nm) and the highest H(2)evolution rate of 1275.42 mu mol h(-1)g(-1)was approximately 3.73- and 32.25-times higher than those of pristine g-C3N4(341.85 mu mol h(-1)g(-1)) and pure CeO2(39.55 mu mol h(-1)g(-1)), respectively. Superoxide (O-2(-)) and hydroxyl (OH) radicals were also confirmed to be formed on the sample surface for TC photocatalytic degradation. As an electronic medium, NCQDs transferred electrons between the g-C(3)N(4)and CeO(2)interface to promote the electron-hole separation. This work affords a helpful perspective for synthesizing efficient charge separation and environmentally friendly photocatalysts by controlling the surface heterostructure.