A comparison of graphitic carbon nitrides synthesized from different precursors through pyrolysis

Two precursors, melamine and urea, were used to prepare graphitic carbon nitride through a thermal decomposition (pyrolysis) method. The pyrolysis was carried out at different temperatures in open air condition in a crucible with cover. The as-prepared samples were characterized by SEM, TEM, BET, XRD, XPS, FTIR and DRS. The characterization results revealed that the samples synthesized from different precursors had different physical and chemical properties. Specifically, it was found that the pyrolysis of urea yielded product with smaller crystalline domains but larger surface areas compared to that of melamine. To further qualify the as-prepared samples, the adsorption and photocatalytic activities were measured by using Rhodamine B (RhB) as target pollutant. It was found out that the precursors as well as pyrolysis temperatures had big influences on the adsorption and photocatalytic activities. Higher photocatalytic activities were achieved by samples synthesized from urea at higher temperatures. The mechanism of the degradation process was explored on the basis of the band structure and the roles of photo-generated radicals. (C) 2016 Elsevier B.V. All rights reserved.