IHJPAS. 36 (3) 2023 260 This work is licensed under a Creative Commons Attribution 4.0 International License *Coressponding Author: khalilibrahimalabid@gmail.com Abstract Graphene-carbon nitride can be synthesized from thiourea in a single step at a temperature of four hours at a rate of 2.3 ℃/min. Graphene-carbon nitride was characterized by Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray analysis (EDX), scanning electron microscopy, and spectrophotometry (UV-VIS). Graphene-carbon nitride was found to consist of triazine and heptazine structures, carbon, and nitrogen. The weight percentage of carbon and the atomic percentage of carbon are 40.08%, and the weight percentage of nitrogen and the atomic percentage of nitrogen are 40.08%. Therefore, the ratio and the dimensions of the graphene-carbon nitride were characterized by scanning electron microscopy, and it was found that the radius was within the range of (2 µm-147.1 nm). In addition, it was found that it absorbed light in the visible field (VIS). The objective of the manufacture and characterization of graphene-carbon nitride for use in the manufacture of a selective electrode for an organic pollutant (currently used in the manufacture of a selective electrode for the analysis of organic dye). Keywords: Graphene-Carbon Nitride, Structural characterization, Carbon Sheets, Polymer, Thermal method. 1. Introduction Increasing interest in the field of nanotechnology, especially graphene and graphene-carbon nitride g − C3N4 is due to their interesting electrical, thermal, and mechanical properties. Graphene-carbon nitride g − C3N4 is a two-dimensional sheet(2D) [1-2] Metal-free [3-6], and semiconductor [7]. Band gaps are ( 2.7 eV) [8-9], hybridization sp2 − hybridized [10] and π − conjugated [11] . Graphene-carbon nitride g − C3N4 can be prepared from several materials in the presence of temperature: melamine [12-13], dicyandiamide [14-15], trithiocyanuric acid [16- 17], urea [18-21], thiourea [22-23], cyanamide [24], as shown in Figure1: doi.org/10.30526/36.3.3103 Article history: Received 11 November 2022, Accepted 30 March 2023, Published in July 2023. Ibn Al-Haitham Journal for Pure and Applied Sciences Journal homepage: jih.uobaghdad.edu.iq Synthesis and Characterization Graphene- Carbon Nitride Nanostructure in One Step *Khalil Ibrahim Alabid Department of Chemistry ,Analytical Chemistry , Faculty of Science , Tishreen University ,Lattakia ,Syria. khalilibrahimalabid@gmail.com Hajar Naser Nasser Department of Chemistry ,Analytical Chemistry , Faculty of Science , Tishreen University ,Lattakia ,Syria. Hajar.n.nasser@gmail.com https://creativecommons.org/licenses/by/4.0/ mailto:khalilibrahimalabid@gmail.com mailto:khalilibrahimalabid@gmail.com mailto:khalilibrahimalabid@gmail.com mailto:Hajar.n.nasser@gmail.com IHJPAS. 36 (3) 2023 261 Figure 1. Materials that can be used in the synthesis for 𝒈 − 𝑪𝟑𝑵𝟒 Graphene-carbon nitride g − C3N4 is used in many applications, including: solar cells [25-26], super-capacitors [27-28], energy storage [29-30], and in the manufacture of electrochemical sensors, such as the mercury sensor [31]. The nitro sensor 𝑁𝑂𝑋 [32], the hydrogen sulfide sensor H2S [33], which is sensitive to silver ions 𝐴𝑔 + [34]. It is also used in fuel cells [35-36], the pharmaceutical and medical sides [37-38]. Recently, many studies have focused on the optical applications of g − C3N4 photo catalytic applications [39-44]. The g − C3N4 can be used in the removal and dissolution of many organic pollutants [45-47], also used to remove 𝐶𝑂2 gas from the air [48]. Recently, the g − C3N4 is used to generate hydrogen and oxygen from water according to the following potentials and equations (1-2-3) [49]: Full reaction: 2H2O(l) → O2(g) + H2(g) ∆E 0 = 1.23 V. (1) Half-reaction: Oxidation reaction: 2H2O(l) → O2(g) + 4H +(aq) + 4e− ∆E0 = 1.23 V vs. SHE(2) Reduction reaction: 4H+(aq) + 4e− → 2H2(g) ∆E0 = 0.00 V vs. SHE(3) 𝐸0 is the equilibrium potential under the standard conditions and 𝑆𝐻𝐸 is the standard hydrogen electrode The g − C3N4 is a semiconductor used to increase its effectiveness. It is mixed with other materials; this doping is a suitable and effective technique to modify the band gap reducing the resistance of the large interface layer, enhancing the photocatalytic activity of g − C3N4 and removing to improve its properties as well. One of the strategies to improve the band gap, and enhance the photo catalytic activity of graphene-carbon nitride is to add doping, as shown in figure 2 [50]. Figure 2. Band gap positioning with respect to conduction and valence band potentials of bare 𝒈 − 𝑪𝟑𝑵𝟒 and non- precious metal doped 𝒈 − 𝑪𝟑𝑵𝟒 IHJPAS. 36 (3) 2023 262 The formation of g − C3N4 from its materials depends on time and temperature affects the spacing of the graphene-carbon nitride layers from each other, as in Figure 3: Figure 3. A schematic diagram of the formation of 𝒈 − 𝑪𝟑𝑵𝟒 nanosheets and their thermal effect at 𝟓𝟎𝟎 ℃ in air [51]. To confirm the fabrication of graphene-carbon nitride, measurements are done by fourier- transform infrared spectroscopy (FTIR), [52-64] and energy dispersive x-ray analysis (EDX) [65- 68]. The objective of the manufacture is at 580 ℃ degrees, which is a critical point for its manufacture. The objective of the manufacture and characterization of graphene-carbon nitride is performed for use in the manufacture of a selective electrode for an organic pollutant, (currently it is used in the manufacture of a selective electrode for the analysis of organic dye). 2. Chemical, instruments and method The chemicals used in this research are high-purity materials: thiourea CH₄N₂S, thermal furnace (CARBOLITE), energy dispersive X-ray analysis (EDX), which is company namel; EDAX, scanning electron microscopy (SEM), which is a company name; TESCAN model VEGA II Xmu; spectrophotometer (UV-VIS) D-Lab model SP-UV1000; Fourier-transform infrared spectroscopy (FTIR); Balance Sartorius type TE64, porcelain crucible; and agate mortar. Graphene-carbon nitride 𝑔 − 𝐶3𝑁4 is made by an easy, one-step method, through the direct polymerization process of thiourea, approximately 5.0016 g of thiourea is placed in a covered crucible of 50 ml, and then heated at 580 ℃ for 4 ℎ in a muffle furnace. The temperature is gradually increased at a rate of 2.3 ℃/𝑚𝑖𝑛, and then left to cool to reach the temperature of the laboratory. Then it is ground in an agate mortar, and we get a yellow powder, as in Figure 4. When it is manufactured at 580 ℃ which is a critical point for its manufacture, when the temperature 600 ℃ , it is noted that there is disappearance in the porcelain crucible, which denotes the decomposition of thiourea. IHJPAS. 36 (3) 2023 263 Figure 4. Photographs of the formation stages of carbon nitride sheets 𝒈 − 𝑪𝟑𝑵𝟒 A) Thiourea weight B) incineration at a temperature of 580 ℃ for four hours at a rate of 2.3 ℃/min C) after cooling D) grinding the product in an agate mortar 3. Results and Discussion: The graphene carbon nitride 𝑔 − 𝐶3𝑁4 was characterized using FTIR spectroscopy based on molecular vibration within the range of (500 − 4000) 𝑐𝑚−1 shown in Figure 5. Figure 5. FTIR Spectroscopy for 𝒈 − 𝑪𝟑𝑵𝟒 Peaks at 808.7 𝑐𝑚−1and 888.2 𝑐𝑚−1 correspond to the presence of s-triazine in 𝑔 − 𝐶3𝑁4. This bending is caused by the vibration of the tri-s-triazine (heptazine) ring. The peaks from 1242.6 𝑐𝑚−1 to 1632.5 𝑐𝑚−1 are attributed to the expansion vibration of the heterocyclic 80 8. 7 88 8. 2 12 42 .6 13 19 .5 13 85 .0 14 11 .9 15 68 .1 16 32 .5 23 61 .5 34 26 .9 4 04 2 4- g- C 3N4 ( 58 0) re p 2- -T hu S ep 2 3 0 1:0 5:1 0 2 0 10 (G MT+0 3 :00 ) 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 % Tr an sm itt an ce 500 1000 1500 2000 2500 3000 3500 4000 Wavenum bers (cm -1) IHJPAS. 36 (3) 2023 264 aromatic C6N7 heptazine. Peaks are observed at 1319.5 𝑐𝑚 −1, 1385.0 𝑐𝑚−1, 1411.9 𝑐𝑚−1, and 1568.1𝑐𝑚−1 sticking together due to stretching vibrations of the C − N bonds, while a peak appears at 1632.5 cm−1 related to the expansion vibration of the C − N bond with heptazine units. Peaks between 900 cm−1 and 1800 cm−1 are attributed to the trigonal C – N (– C) – C or C − NH − C in ring. The absorption band centered at 3426.9 cm−1 corresponds to the vibrational stretching of the N − H bond which denotes the presence of NH and NH2 groups at edges in the g − C3N4 . The broad peaks between 3000 cm −1 and 3500cm−1 are contributed by the lengthening of N –H [52-64]. So, graphene-carbon nitride is consisted the triazine and tri-s-triazine (heptazine) [69-74], as in Figure 6. Figure 6. Tri-s-triazine (heptazine) and triazine structures of 𝒈 − 𝑪𝟑𝑵𝟒 The process of manufacturing g − C3N4 depends on the formation of a polymer from thiourea after exposure to temperature, as is shown in Figure 7. IHJPAS. 36 (3) 2023 265 Figure 7. The stages of 𝒈 − 𝑪𝟑𝑵𝟒 polymerization from thiourea The 𝑔 − 𝐶3𝑁4 is characterized by energy dispersive X-ray analysis (EDX) as in table (1) and Figure 8 : Figure 8. spectrum for 𝒈 − 𝑪𝟑𝑵𝟒 by (EDX) IHJPAS. 36 (3) 2023 266 Table1. Elemental analysis 𝑔 − 𝐶3𝑁4 by energy dispersive X-ray analysis (EDX) Element Weight Atomic Error Net Int. K Ratio Z R A F C K 36.45% 40.08% 3.77% 2795.78 0.2654 1.0132 0.9936 0.719 1 N K 63.55% 59.92% 9.85% 1065.86 0.0854 0.9921 1.0035 0.1356 1 The energy dispersive X-ray analysis (EDX) showed that there is a peak at 0.27𝑘𝑒𝑉 indicating the presence of 𝐶 − 𝐾 carbon, and a peak at 0.39 𝑘𝑒𝑉 indicating the presence of N-K nitrogen, the weight percentage of carbon is 36.45 %, and the atomic percentage of carbon is 40.08%, and the weight percentage of nitrogen is 63.55 %, and the atomic percentage of nitrogen is 59.92 %, so the ratio is 3 𝐶 and 4 𝑁 .The 𝑔 − 𝐶3𝑁4 is characterized using scanning electron microscopy (SEM) as shown in Figure 9 . Figure 9. SEM scanner for 𝒈 − 𝑪𝟑𝑵𝟒 sheet sheet IHJPAS. 36 (3) 2023 267 From the SEM scanning and using the Image J program, it is found that the shape is 𝑔 − 𝐶3𝑁4 graphene-carbon nitride sheets, which are lamellar interfaces (sheet) with a radius within the range of (2 µm -147.1 nm). The optical spectrum is studied for the graphene - carbon nitride g-C3N4 sheets, as shown in Figure 10: Figure 10. Scanning spectrum of 0.005 g/5ml of 𝑔 − 𝐶3𝑁4 The solution is absolute A) ethanol B) distilled water It is noted that 𝑔 − 𝐶3𝑁4 is not soluble in solutions (water - ethanol) and it has a superior ability to absorb visible light 𝑔 − 𝐶3𝑁4 [8,9]. This is due to its band gap of 2.7 eV [8, 9, 75] by spectrophotometry 4. Conclusion Graphene-carbon nitride can be synthesized from thiourea in a single-step. Graphene-carbon nitride is characterized. It is found to consists of triazine and heptazine structures. It also consists of carbon and nitrogen. 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