Crystalline C3N4/CeO2composites as photocatalyst for hydrogen production in visible light

Abstract Crystalline carbon nitride (C-C 3 N 4 ) doped with cerium oxide (CeO 2 ) was synthesized using ionothermal method to increase the photocatalytic activity for H 2 production. Graphitic carbon nitride (g-C 3 N 4 ) obtained from direct pyrolysis of urea at 550°C was subsequently annealed with a mixture of KCl and LiCl to obtain C-C 3 N 4 . CeO 2 was doped onto C-C 3 N 4 and g-C 3 N 4 via calcination at 550°C. XRD analysis showed the formation of high intensity C 3 N 4 and CeO 2 peaks in C-C 3 N 4 /CeO 2 , meanwhile g-C 3 N 4 /CeO 2 only showed CeO 2 peaks. FTIR analysis confirmed all the samples contained C 3 N 4 polymeric structure. The specific surface area of g-C 3 N 4 was measured at 61 m 2 /g. The surface area increased to 92 m 2 /g when g-C 3 N 4 transformed into C-C 3 N 4 , and further increased to 106 m 2 /g on C-C 3 N 4 /CeO 2 . The photocatalytic activity for H 2 gas production showed significant increase of H 2 rate on C-C 3 N 4 /CeO 2 compared to g-C 3 N 4 /CeO 2 and g-C 3 N 4 . The high crystallinity and high surface area were suggested to enhance photocatalytic activity of C-C 3 N 4 /CeO 2 in visible light presumably due to the increase of electron and hole lifetimes.