Higher Yield Urea-Derived Polymeric Graphitic Carbon Nitride with Mesoporous Structure and Superior Visible-Light-Responsive Activity

A series of mesoporous graphitic carbon nitride (mg-C₃N₄) materials have been prepared with urea and tetraethylorthosilicate (TEOS) as the precursors, which were thermally polycondensed to obtain the g-C₃N₄/silica composites, after silica was removed, mg-C₃N₄ with large surface area (170 m² g^-1) was successfully prepared. Excitingly, TEOS did not only act as a mesoporous-directing agent but also as the promoter for the urea polycondensation to g-C₃N₄, which made the urea polycondensation proceed at relatively low temperature. Thus, volatilization or/and decomposition of urea in the process of thermal treatment were reduced, resulting in the product yield of g-C₃N₄ from 0.3 to 0.4 g/10 g urea remarkably increasing to 1.2 g/10 g urea. Moreover, superior photocatalytic activities were observed for degrading methyl orange (MO) and H₂ generation from water splitting over the mg-C₃N₄ photocatalyst. The facilely developed method for high-yield mesoporous g-C₃N₄ from cost-effective urea was more attractive for its wide applications in environmental treatment and energy development fields.