A Novel Approach to Synthesize Nitrogen-Deficient g-C₃N₄for the Enhanced Photocatalytic Contaminant Degradation and Electrocatalytic Hydrogen Evolution

Abstract

Graphitic carbon nitride with nitrogen vacancies was successfully synthesized by the three-step method for the calcination of melamine, following urea-assisted hydrothermal and jacjoin calcination approach. The structural, surface, optical and electric properties were characterized by XRD, FT-IR, SEM, TEM, UV–Vis DRS, PL, N2 physical adsorption/desorption and electrochemical methods, which proved that this strategy of modifying g-C3N4 by nitrogen vacancies not only increased the specific surface area, exposed more active sites, but also inhibited the recombination of photogenerated carriers on the surface of photocatalysts, resulting in the enhancement of photocatalytic and electrocatalytic performances. The photocatalytic activities were measured under visible light irradiation ([Formula: see text][Formula: see text]nm), and their degradation efficiencies could be achieved for 99.8%, 55%, 100% and 99.7% corresponding to that of rhodamine B, acid orange II, methyl orange and methylene blue, respectively. The trapping experiments demonstrated that [Formula: see text] played an important role in the degradation process. In addition, being an active electrocatalyst, nitrogen-deficient g-C3N4 showed a lower Tafel slope, smaller overpotential and the more effective electrochemical surface area compared with that of bare g-C3N4 in neutral media. This work underlines the importance of defect engineering to promote catalytic performance, which can provide a simple and efficient way for modifying g-C3N4 and other N-based catalysts.

Comprehensive Review on Multifaceted Carbon Dot Nanocatalysts: Sources and Energy Applications

“…Moreover, the use of Pt as a catalyst in an alkaline environment is hindered by hydroxyl ion (−OH) poisoning, necessitating the substitution of a highly stable and low overpotential Pt catalyst. In this context, CDs, along with their metallic and non-metallic counterparts, could serve as an efficient electrocatalyst [56,101,102].…”

Doping of Graphitic Carbon Nitride with Non-Metal Elements and Its Applications in Photocatalysis

“…By introducing additional energy levels and acting as reactive sites, vacancies can play a significant role in medication of the properties of photocatalysts (Table 6). The most common strategies of synthesis of nitrogen or carbon defective g-C 3 N 4 are the post-heat treatment in H 2 or Ar [127,141], the polymerization in various atmospheres [88,128,129], the post-heat treatment with a reducing agent [88,130,131], the thermal copolymerization with agents that deliberates gas [132,133,138], and the quick post-thermal treatment [135,136,139,142].…”

“…The enhanced ESR signal at g = 1.9997 (Figure 9b) illustrated the presence of unpaired electrons on the C atoms, which appeared due to the loss of N atoms (Figure 9c). The alternative way to modulate the g-C3N4 electronic band structure to favor visible light harvesting, accelerate charge separation, and transport was reported to be homogeneous selfmodification with nitrogen [127][128][129][130][131][132][133][134][135][136][137][138] or carbon [88,[139][140][141] vacancies. Native point defect doping via thermal treatment is an easy and promising method to tune the electrical transport properties of semiconductors made for renewable-energy conversion.…”

Preparation and photocatalytic properties of ZnO nanorods/g-C3N4 composite

“…Therefore, using solar energy to solve environmental problems has become a research hotspot in recent years. In this context, as one of the effective methods to solve the problems, semiconductor photocatalysis technology has attracted great attention [3][4][5]. Semiconductor photocatalysis technology is the use of semiconductor materials to activate the surface energy under the excitation of sunlight, which can be efficiently used in the catalytic synthesis of organic fuels, degradation of organic pollutants, reduction of heavy metal ions, disinfection and sterilization and other fields.…”