High surface area, spongy graphitic carbon nitride derived by selective etching by Pt and Ru nanoparticles in hydrogen

It was observed for the first time that the specific surface area of graphitic carbon nitride (g-C 3 N 4 ) increased from 32 m 2 g −1 to 142 and 171 m 2 g −1 for Pt and Ru, respectively, due to the etching of g-C 3 N 4 by Pt and Ru nanoparticles. Metal nanoparticles catalyze hydrogenation of C – N bonds and “move” through the structure of g-C 3 N 4 etching tunnels in it and creating “spongy graphitic carbon nitride” (sgCN). The reactions take place on the surface of metal NPs, which are covered with oxidized forms of Pt and Ru capable of strong interactions with nitrogen, which was confirmed by XPS studies. The activation energy of hydrogenation of g-C 3 N 4 is 112 and 151 kJmol −1 for Ru and Pt nanoparticles, respectively. The process of etching of g-C 3 N 4 was observed by mass spectrometry and temperature programmed reduction coupled with on-line infrared spectroscopy. On the basis of thermodynamic considerations and quantum mechanical calculations of bonds strengths, a probable mechanism of g-C 3 N 4 hydrogenation was proposed. Graphical abstract