Graphitic carbon nitride based nanocomposites for the photocatalysis of organic contaminants under visible irradiation: Progress, limitations and future directions

Abstract

Graphitic carbon nitride (g-CN) has drawn great attention recently because of its visible light response, suitable energy band gap, good redox ability, and metal-free nature. g-CN can absorb visible light directly, therefore has better photocatalytic ability under solar irradiation and is more energy-efficient than TiO. However, pure g-CN still has the drawbacks of insufficient light absorption, small surface area and fast recombination of photogenerated electron and hole pairs. This review summarizes the recent progress in the development of g-CN nanocomposites to photodegrade organic contaminants in water. Element doping especially by potassium has been reported to be an efficient method to promote the degradation efficacy. In addition, compound doping improves photodegradation performance of g-CN, especially AgPO-g-CN which can completely degrade 10mgL of methyl orange under visible light irradiation in 5min, with the rate constant (k) as high as 0.236min. Moreover, co-doping enhances the photodegradation rate of multiple contaminants while immobilization significantly improves catalyst stability. Most of g-CN composites possess high reusability enabling their practical applications in wastewater treatment. Furthermore, environmental conditions such as solution pH, reaction temperature, dissolved oxygen, and dissolved organic matter all have important effects on the photocatalytic ability of g-CN photocatalyst. Future work should focus on the synthesis of innovative g-CN nanocomposites for the efficient removal of organic contaminants in water and wastewater.

Recent Development of Graphitic Carbon Nitride-Based Photocatalyst for Environmental Pollution Remediation

“…Since the potential of carbon nitride in the photocatalysis arena had been known, various synthesis method and technique had been instigated such as chemical vapor deposition, sonochemical, solvothermal, and thermal annealing of nitrogen-rich precursor [24,32,33]. Following the variation in synthesis technique, the various compound can be used as the precursor such as melamine, cyanamide, dicyanamide, urea, and thiourea.…”

“…However, the practical application of g-C 3 N 4 is still hindered by some of its individual properties such as low visible light utilization, the high recombination rate of photogenerated electron-hole pairs and slow electron transfer which lead to lower photocatalytic performance [22]. Hence, various strategies have been adopted such as energy band engineering, copolymerization with nitrogen precursor and development of heterostructure system in order to overcome the individual drawbacks of pristine g-C 3 N 4 [24][25][26].…”

Metal-Free Carbon Quantum Dots Implant Graphitic Carbon Nitride: Enhanced Photocatalytic Dye Wastewater Purification with Simultaneous Hydrogen Production

“…Therefore, in order to enhance the application potential of g-C 3 N 4 , many strategies were developed, such as coupling with other different materials and morphology control [16,17]. Recently, carbon quantum dots (CQDs) have been successfully deposited on the g-C 3 N 4 backbone to enhance its photocatalytic activity through increasing the electron transfer and reservoir properties [18][19][20][21]. Since then, several types of CQDs modified g-C 3 N 4 nanocomposites have been produced and have been proven to possess an impressive performance for photocatalytic dye wastewater purification or solar water splitting.…”

Co3(PO4)2/Ag3PO4 with enhanced simulated sunlight photocatalytic activity toward ofloxacin degradation and mechanism insight

“…However, some researchers considered Ag 3 PO 4 to suffer from poor photostability due to fast photoreduction of Ag ions to metallic Ag. Various Ag 3 PO 4 ‐based composite photocatalysts have been proposed . Notably, cocatalysts on the surface of base semiconductor particulates could improve the stability of photocatalysts by timely consumption of charge carriers and, most importantly, lower the activation energy of surface redox reactions .…”

“…Various Ag 3 PO 4 -based composite photocatalysts have been proposed. 18,19 Notably, cocatalysts on the surface of base semiconductor particulates could improve the stability of photocatalysts by timely consumption of charge carriers and, most importantly, lower the activation energy of surface redox reactions. 20 For example, Ag 3 PO 4 /ZnO, Co 3 O 4 /Ag 3 PO 4 and others were developed.…”