Synthesis of graphitic carbon nitride by heating mixture of urea and thiourea for enhanced photocatalytic H2 production from water under visible light

Abstract

In this study, the g-C3N4 was prepared by recrystallization and calcining the mixture of urea and thiourea. The obtained samples show high photocatalytic performance for H2 evolution under visible light (λ > 420 nm) irradiation in the presence of triethanolamine as sacrificial reagent. The g-C3N4 was characterized by X-ray diffraction (XRD), nitrogen physisorption, XPS, UV–visible spectroscopy, element analysis (EA), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopic (SEM) and photoluminescence (PL) spectroscopy analysis. The experimental results indicated that the samples derived from the mixture of urea and thiourea contributed to enlarge the specific surface area of g-C3N4 and decrease the recombination of photo-induced electron-hole pairs, consequently enhancing photocatalytic activity. The influence of different mass fraction of thiourea on the H2 evolution rate was explored in the presence of triethanolamine as sacrificial reagent under visible light (λ > 420 nm) irradiation. The photocatalytic results indicated that the sample with optimal photocatalytic activity is derived from the mixture with a thiourea's mass fraction of 2.44%. The optimal H2 evolution rate is 2.60 times and 6.17 times higher than that over g-C3N4 from urea and g-C3N4 from thiourea, respectively.