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

Abstract

AbstractCrystalline carbon nitride (C-C3N4) doped with cerium oxide (CeO2) was synthesized using ionothermal method to increase the photocatalytic activity for H2production. Graphitic carbon nitride (g-C3N4) obtained from direct pyrolysis of urea at 550°C was subsequently annealed with a mixture of KCl and LiCl to obtain C-C3N4. CeO2was doped onto C-C3N4and g-C3N4via calcination at 550°C. XRD analysis showed the formation of high intensity C3N4and CeO2peaks in C-C3N4/CeO2, meanwhile g-C3N4/CeO2only showed CeO2peaks. FTIR analysis confirmed all the samples contained C3N4polymeric structure. The specific surface area of g-C3N4was measured at 61 m2/g. The surface area increased to 92 m2/g when g-C3N4transformed into C-C3N4, and further increased to 106 m2/g on C-C3N4/CeO2. The photocatalytic activity for H2gas production showed significant increase of H2rate on C-C3N4/CeO2compared to g-C3N4/CeO2and g-C3N4. The high crystallinity and high surface area were suggested to enhance photocatalytic activity of C-C3N4/CeO2in visible light presumably due to the increase of electron and hole lifetimes.