Large-scale production of graphitic carbon nitride with outstanding nitrogen photofixation ability via a convenient microwave treatment

Highlights: • Microwave method for synthesizing g-C₃N₄ with N₂ photofixation ability is reported. • Nitrogen vacancies play the important role on the nitrogen photofixation ability. • The present process is a convenient method for large-scale production of g-C₃N₄. - Abstract: A convenient microwave treatment for synthesizing graphitic carbon nitride (g-C₃N₄) with outstanding nitrogen photofixation ability under visible light is reported. X-ray diffraction (XRD), N₂ adsorption, UV–vis spectroscopy, SEM, N₂-TPD, EPR, photoluminescence (PL) and photocurrent measurements were used to characterize the prepared catalysts. The results indicate that microwave treatment can form many irregular pores in as-prepared g-C₃N₄, which causes the increased surface area and separation rate of electrons and holes. More importantly, microwave treatment causes the formation of many nitrogen vacancies in as-prepared g-C₃N₄. These nitrogen vacancies not only serve as active sites to adsorb and activate N₂ molecules but also promote interfacial charge transfer from catalysts to N₂ molecules, thus significantly improving the nitrogen photofixation ability. Moreover, the present process is a convenient method for large-scale production of g-C₃N₄ which is significantly important for the practical application.