Synthesis of salicylic acid-modified graphite carbon nitride for enhancing photocatalytic nitrogen fixation

Finding an efficient and environment-friendly photocatalyst is significant for photocatalysis. In this research, a simple calcination with urea and salicylic acid (SA) is created for constructing a SA-modified graphite carbon nitride (g-C3N4-SA) photocatalyst. Compared to pure g-C3N4, g-C3N4-SA presents broadened light absorption, due to n -> pi* transition at nitrogen atoms. Interestingly, SA modification can strongly affect chemical and physical properties of g-C3N4, including increasing Brunauer-Emmett-Teller (BET) specific area, forming porous structure, improving optical absorption and promoting carrier separation, thus achieving the improved photocatalytic activity of g-C3N4-SA. The optimum g-C3N4-SA with the mass of SA 0.05 g (g-C3N4-SA-0.05) presents a high ammonia evolution rate of 7.92 mmol L-1 h(-1) g(-1), 2.5 and 1.4 times than g-C3N4(3.2 mmol L-1 h(-1) g(-1)) and g-C3N4 loaded with Pt (5.47 mmol L-1 h(-1) g(-1)). Furthermore, the excellent photostability of g-C3N4-SA is also achieved. (C) 2020 Elsevier Inc. All rights reserved.