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Communication

Synthesis of Porous Carbon Nitride Nanobelts for Efficient Photocatalytic Reduction of CO2

by
Zhiqiang Jiang
1,
Yirui Shen
1 and
Yujing You
1,2,*
1
School of Materials Science and Chemical Engineering, Ningbo University of Technology, Ningbo 315211, China
2
Zhejiang Institute of Tianjin University, Ningbo 315201, China
*
Author to whom correspondence should be addressed.
Molecules 2022, 27(18), 6054; https://doi.org/10.3390/molecules27186054
Submission received: 11 August 2022 / Revised: 8 September 2022 / Accepted: 13 September 2022 / Published: 16 September 2022
(This article belongs to the Special Issue Electrochemical CO2 Conversion to Value-Added Products)
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Abstract

:
Sustainable conversion of CO2 to fuels using solar energy is highly attractive for fuel production. This work focuses on the synthesis of porous graphitic carbon nitride nanobelt catalyst (PN-g-C3N4) and its capability of photocatalytic CO2 reduction. The surface area increased from 6.5 m2·g−1 (graphitic carbon nitride, g-C3N4) to 32.94 m2·g−1 (PN-g-C3N4). C≡N groups and vacant N2C were introduced on the surface. PN-g-C3N4 possessed higher absorbability of visible light and excellent photocatalytic activity, which was 5.7 and 6.3 times of g-C3N4 under visible light and simulated sunlight illumination, respectively. The enhanced photocatalytic activity may be owing to the porous nanobelt structure, enhanced absorbability of visible light, and surface vacant N-sites. It is expected that PN-g-C3N4 would be a promising candidate for CO2 photocatalytic conversion.

1. Introduction

Significantly increased CO2 concentration in the atmosphere has caused problems such as air pollution and global warming in the past decades, posing a serious threat to our future generations [1,2]. In order to alleviate these issues, innovative and sustainable technologies are needed to effectively capture and convert CO2. Sustainable conversion of CO2 to high value-added products not only helps to reduce the content of CO2 in the atmosphere but also promotes the carbon cycle [3,4]. However, due to the lack of efficient, stable, and selective catalysts, the research on CO2 photoreduction is still progressing slowly.
Carbon nitride, a low-cost, thermally stable, and nontoxic material with a band gap of 2.7 eV and well-matched requirements of various redox reactions, shows excellent photocatalytic activity [5,6]. However, both low surface area and separation efficiency of photogenerated electron-hole pairs can depress the photoactivity of g-C3N4 [7,8]. Various methods have been developed to solve these problems, such as nonmetal element doping [9], metal oxide or hydroxides [10,11], ion doping [12,13], noble metal deposition [14,15], controlling morphology [16,17], and loading on carriers [18,19]. Previous research has demonstrated the great potential of g-C3N4 in photocatalytic fields, including carbon dioxide reduction, water splitting, organic pollutant degradation, and organic transformations [5,20].
In bulk g-C3N4, the stacked 2D single layers are held together in place by weak van der Waals forces of attraction [21]. Aiming to provide more reaction sites, exfoliation has been of particular interest for modifying g-C3N4 in recent years. g-C3N4 is treated with thermal exfoliation [20], concentrated acid treatment [22], and ultrasonic exfoliation [23] to synthesize nanoribbon or nanobelt samples. In this study, we used melamine as the precursor and a mixed solution of distilled water and ethylene glycol as the solvent. Melamine molecularly dissolved in the mixed aqueous solution at elevated temperature and polymerized into porous carbon nitride nanobelt (PN-g-C3N4), as displayed in Figure 1. The thin layer may be formed due to the polyols introduced into the interlayer [24] in the hydrothermal process and ultrasonic-induced exfoliation [25] in the washing stage of supramolecular precursor. Meanwhile, during thermal calcination process the released gas and volume shrinkage of precursor would create many pores on the layers, finally producing porous few-layer C3N4. The morphologies, microstructures, and physicochemical properties of the photocatalyst were studied. CO2 was used as the raw material to evaluate PN-g-C3N4 photocatalytic performance under visible light and simulated sunlight. The obtained PN-g-C3N4 was confirmed to be an efficient photocatalyst in the conversion of CO2.

2. Results

2.1. SEM Analysis

Figure 2 presents the morphologies and micro-structures of PN-g-C3N4 and g-C3N4 samples. The as-obtained PN-g-C3N4 nanobelts are characterized with thickness of 30–80 nm with a lateral size of micrometers. It can be seen that PN-g-C3N4 has loose nanobelt structures with pores in its framework (Figure 2a,b). The existence of a large number of edges and pores in the obtained porous nanobelt structures is extremely important for improving the photochemical and catalytic performance of carbon nitride. On the contrary, g-C3N4 has bulk structure (Figure 2c,d), which is formed by lamellar structures stacking with each other.
The nitrogen adsorption–desorption isotherms of the samples are presented in Figure 3a. Both g-C3N4 and PN-g-C3N4 exhibited a type IV isotherm with a hysteresis loop at P/Po = 0.6–1.0. The pore sizes in PN-g-C3N4 are about 3–20 nm, which is attributed to the pores formed in the porous nanobelt structures (Figure 3b). The BET surface areas of g-C3N4 and PN-g-C3N4 were calculated to be 6.5 m2·g−1, and 32.94 m2·g−1, respectively. The specific surface area of PN-g-C3N4 increases greatly due to its porous nanobelt structures, which is beneficial for the exposure of more active catalytic sites.

2.2. IR and UV-Vis DRS Analysis

The FTIR spectrum for g-C3N4 and PN-g-C3N4 (Figure 4) showed a peak at 807 cm−1 typical for the out-of-plane bending mode of heptazine rings, whilst peaks locked between 800 and 1800 cm−1 originated from N-C=N heterorings [26]. The peak at 3000–3500 cm−1 corresponded to N-H stretching vibrations. For the PN-g-C3N4 samples, a new peak centered at 2173 cm−1 is found in the spectrum, which is assigned to an asymmetric stretching vibration of C≡N triple bond. The other change was the decrease in the intensity of the N-H stretching peaks between 3000 and 3300 cm−1. The results suggest the synthesis of PN-g-C3N4 decreases the concentration of N-H groups and introduces C≡N groups. The existence of C≡N groups in PN-g-C3N4 is supposed to increase the electron delocalization and adjust band structures, beneficial for visible-light absorption and photon-generated carrier separation [27].
The optical absorption properties of the photocatalyst have a great effect on the photocatalytic performance. In order to investigate the optical absorption properties of the samples, diffuse reflectance absorption spectra were recorded on UV-Vis system. The optical absorption spectra of g-C3N4 and PN-g-C3N4 are displayed in Figure 5a. The absorption edge of g-C3N4 was at around 460 nm. However, the absorption spectrum of PN-g-C3N4 extends to the more visible light region from 420 nm to 800 nm. The results demonstrate that PN-g-C3N4 has enhanced optical adsorption of the visible light, which ascribe to large number of edges and pores in the obtained porous nanobelt structures. The band gaps of g-C3N4 and PN-g-C3N4 are presented in Figure 5b. The band gap of PN-g-C3N4 (2.50 eV) is lower than that of g-C3N4 (2.68 eV). These changes are related to quantum confinement effect, due to excitation into the lower energy defect states [28]. The relatively low band gap of PN-g-C3N4 allows it to absorb a good number of photons in the visible domain of the solar spectrum, which is the most important for an effective photocatalyst.

2.3. XRD and XPS Analysis

The XRD pattern for pristine g-C3N4 (Figure 6a) showed two characteristic peaks at 13.0° and 27.4°, which can be assigned to the (100) and (002) crystal planes of g-C3N4, representing in-plane packing and interfacial stacking of g-C3N4 sheets, respectively [29]. The peak at 27.4° of PN-g-C3N4 is weaker and wider, suggesting that the interlayer structure of g-C3N4 has been weakened, which agrees well with the changes in the micro-morphology.
The survey XPS spectra of g-C3N4 and PN-g-C3N4 samples are shown in Figure 6b. The XPS data showed a decrease in the N/C ratio from 1.29 (g-C3N4) to 1.20 (PN-g-C3N4) on the surface, suggesting the introduction of surface N defects. High-resolution XPS peaks of C1s spectra of the g-C3N4 sample in Figure 6c are deconvoluted into three peaks for C-C (285.0 eV), C-N (286.5 eV), and N-C=N (288.5 eV) bonds. Moreover, the high-resolution XPS peaks of N1s spectrum (Figure 6d) is deconvoluted into four peaks. The first peak at 398.9 eV represents the C=N-C bond. The other peaks at 400.3, 401.5, and 404.8 eV belongs to N-(C)3, C-N-H, and π excitation bonds, respectively (Figure 6d). Compared to g-C3N4, PN-g-C3N4 showed a slight shift in all the peaks of C1s (0.1–0.2 eV) and N1s (0.1–0.3 eV) spectra, which may be caused by the defects in the carbon nitride network. Interestingly, the intensity of C-C peaks of PN-g-C3N4 slightly increased. The peak area ratios between C-C and N-C-N of C1s spectra were calculated to be 0.18 and 0.25 for g-C3N4 and PN-g-C3N4 samples, respectively. Similarly, the peak area ratios between C=N-C and N-(C)3 peaks in the N1s spectra were determined to be 4.5 (g-C3N4) and 3.6 (PN-g-C3N4), respectively. It is strong evidence that C=N-C vacancies are formed on the surface of PN-g-C3N4, which can act as entrapping points for charges, yielding longer lifetimes for the charge carrier photoexcitons [30].

2.4. Photocatalytic Performance

The photocatalytic activities of as-prepared g-C3N4 and PN-g-C3N4 are shown in Figure 7. In the range of 420–800 nm, simulated sunlight has the similar profile with visible light. However, simulated sunlight has energy distribution at UV zone (360–420 nm) and NIR zone (820 nm) while these parts of visible light are cut off. Remarkably, the sample PN-g-C3N4 exhibits an excellent CO evolution rate (29.8 μmol·h−1·g−1), which is about 5.7 times that of g-C3N4 (5.2 μmol·h−1·g−1) under the visible light (Figure 7a). The CO evolution rate under simulated sunlight catalyzed by PN-g-C3N4 is 52.6 μmol·h−1·g−1, which is about 6.3 times that of g-C3N4 (8.3 μmol·h−1·g−1). The results confirmed porous nanobelt structures of PN-g-C3N4 can extremely enhance the specific surface area and provide more space for mass transfer and reaction, which in turn improves the photocatalytic activity of the samples. The superior activities of PN-g-C3N4 can also be attributed to enhanced visible-light absorption and N defects.
As presented in Figure 7b, the yield of CO is stable without any significant deactivation after five cycles (15 h illumination), which indicates high photostability of PN-g-C3N4 for the CO2 reduction. It is worth noting that no other gas products such as CH3OH or CH4 generated by PN-g-C3N4 were detected by gas chromatography.
Electrochemical tests were performed in a three-electrode cell with a g-C3N4-coated working electrode to further understand the dynamics of electron transfer at the PN-g-C3N4 surface. Figure 8a shows the current of the electrochemical cell with pulsed light excitation. Under visible light illumination, both g-C3N4 and PN-g-C3N4 generated significant photocurrent, implying efficient photogeneration of charge carriers in both materials that is then transferred to the working electrode. Furthermore, the PN-g-C3N4 showed higher photocurrent intensity than that of g-C3N4, suggesting the higher separation rate of photogenerated charge carriers in the PN-g-C3N4. Additionally, the photocurrent can reproducibly increase and recover in every on-off cycle of irradiation, demonstrating the high stability in practical applications. The photogenerated electrons and holes are likely separated more efficiently in PN-g-C3N4 than in g-C3N4. To test this, photoluminescence (PL) measurements were performed to study the separation of photogenerated electrons and holes in g-C3N4 and PN-g-C3N4. Figure 8b displays the PL spectra of the two samples under 380 nm excitation at room temperature. The strong emission peak of g-C3N4 around 465 nm was derived from the direct band transition. By contrast, the PL intensity of PN-g-C3N4 was 65% lower, indicating the higher efficiency in separation of the photogenerated charge carriers. Furthermore, the morphology change from multi-layer structure (g-C3N4) to thin nanobelts (PN-g-C3N4) would shorten the distance for the photogenerated electrons to reach the surface, thus facilitating the charge separation.
The VB XPS spectra (Figure 8c) shows that the band gap of g-C3N4 and PN-g-C3N4 between the valence band (VB) and Fermi level (Ef) are 2.38 and 2.25 eV [31], respectively. The Mott–Schottky plot (Figure 8d) of g-C3N4 and PN-g-C3N4 illustrates that the flat band potentials are −0.80 and −0.69 V, versus the saturated calomel electrode (SCE). The Fermi levels of g-C3N4 and PN-g-C3N4 are −0.58 and −0.47 V (vs. NHE) [32]. Therefore, the CB and VB potentials of g-C3N4 can be calculated to −0.88 and 1.80 eV, respectively, while the CB and VB potentials of PN-g-C3N4 were equal to −0.72 and 1.78 eV, respectively [33]. The potential position change between g-C3N4 and PN-g-C3N4 is shown in Figure 9, and the band gap structures and charge migration of g-C3N4 and PN-g-C3N4 are illustrated.

2.5. Possible Mechanism

The possible reaction mechanism is discussed for photocatalytic CO2 reduction with water into CO over PN-g-C3N4 as depicted in Figure 10. Generally, the photocatalytic CO2 reduction reaction involves the following three steps: (i) CO2 adsorption and activation; (ii) photo-produced charge carriers’ excitation and transfer to the catalyst surface; and (iii) photocatalytic reaction [34]. Upon illumination with light, the photocatalyst generated electrons (e–) in the CB and holes (h+) in the VB, as shown in Equation (1). Further, the e– are exploited to reduce CO2 to its radical (CO2•−), as shown in Equation (2) [7]. The water (H2O) oxidation arises at VB of the catalyst to produce the energetic protons (H+) and oxygen, as shown in Equation (3). The CO2•−, H+, and e– further boosted the rate CO generation, as shown in Equation (4). In the present investigation, CO was developed, which involves an 2e–/2H+ reduction process [35], as shown in Equation (5). In semiconductors, the numerous e– and H+ transfer by proton-coupled electron transfer mechanism is feasible for multi e– reduction reaction.
PN-g-C3N4 + hυ → PN-g-C3N4* + h++ e−
CO2 + e− + hυ → CO2•−
H2O + 2h+ + hυ → (½)O2 + 2H+
CO2•− + 2H+ + e− + hυ → CO + H2O
CO2 + 2H+ + 2e− + hυ → CO + H2O

3. Materials and Methods

3.1. Materials

The chemical reagents used for the synthesis of PN-g-C3N4 were commercially available reagents. Melamine, hydrochloric acid, and ethylene glycol were purchased from Sigma-Aldrich. All the chemicals were used as received without further purification.

3.2. Synthesis of Catalysts

The PN-g-C3N4 was synthesized using a simple one-pot hydrothermal method. First, in a typical synthesis procedure, melamine (2 g, 99%) was dissolved in the mixture of distilled water (40 mL) and ethylene glycol (20 mL, 99%) to make a clear solution at 60 °C. Then, 2.4 mL concentrated hydrochloric acid (36.5%) was added into 60 mL of this solution by stirring for 10 min. Then, the mixed solution was transferred into a Teflon-lined autoclave and heated at 150 °C for 12 h. The mixture was filtered to remove the solvent and the precipitate was washed several times with ethanol and deionized water under ultrasonication, followed by drying overnight at 60 °C in vacuum oven. The resulting solid was heated at 600 °C for 2 h with a heating rate of 3 °C·min−1. The g-C3N4 was synthesized by directly heating melamine at 500 °C for 2 h with a heating rate of 3 °C·min−1.

3.3. Characterization

XRD spectra were recorded on a Bruker D8 Advance diffractometer (Cu Ka radiation). The IR spectra were collected with a Thermo Nicolet iS50 FTIR spectrometer, equipped with an attenuated total reflection (ATR) setup. Diffuse reflectance absorption spectra were recorded on a Varian Cary 4E UV-Vis system equipped with a Labsphere diffuse reflectance accessory. X-ray Photoelectron Spectroscopy (XPS) experiments were performed on Thermo ESCALAB 250 using monochromatized Al Kα at hυ = 1486.6 eV. Bandgap energy (Eg) of the g-C3N4 and PN-g-C3N4 samples was calculated according to the formula below:
(αhv)1/n = C(hυ − Eg)
where α, υ, and C are the absorption coefficient, light frequency, and a constant, respectively. The parameter n is a pure number corresponding to different electronic transitions (n = 2 or 1/2 for indirect-allowed or direct-allowed transitions, respectively.

3.4. Photoactivity Meaasurements

The photocatalytic CO2 reduction test was performed using a batch process under visible light with a 300 W Xenon lamp. In addition, a 420 nm cutoff filter was used to prevent the UV light and Am1.5 filter was used to simulate solar spectral. In this experiment, as-prepared photocatalyst (10 mg) was ultrasonically dispersed in 10 mL of deionized water using a 50 mL round-bottom quartz photo-reactor. Then, the reactor was tightly closed with a silicone rubber septum and the solution was saturated with CO2 gas for 30 min before the light illumination. After illumination, the gaseous product such as CO was analyzed by gas chromatography.

4. Conclusions

In summary, porous g-C3N4 nanobelts were synthesized via a facile hydrothermal method. The obtained PN-g-C3N4 had abundant pores and edges, high specific surface areas, and possessed C≡N groups and vacant N on the surface, which dramatically improved the photocatalytic performance. This catalyst displayed enhanced optical absorption in the visible range. It efficiently and selectively catalyzed CO2 reduction to CO under both visible light and simulated sunlight illumination. Enhanced visible light absorption and the existence of vacant N-sites on the surface also contributed to the photocatalytic activity of PN-g-C3N4. The successful synthesis of PN-g-C3N4 opens up a new way to improve the photochemical performance of carbon nitride-based catalyst.

Author Contributions

Z.J.: investigation; writing—review and editing. Y.S.: investigation; methodology. Y.Y.: supervision; funding acquisition; writing—review and editing. All authors have read and agreed to the published version of the manuscript.

Funding

We gratefully acknowledge the funding from National Natural Science Foundation of China (No.21207095), Basic Commonweal Project of Zhejiang province (LGG22E080012) and Zhejiang Institute of Tianjin University (ZITJU2022-ZYHY017, ZITJU2022-ZYHY011).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Jens, C.M.; Müller, L.; Leonhard, K.; Bardow, A. To Integrate or Not to Integrate—Techno-Economic and Life Cycle Assessment of CO2 Capture and Conversion to Methyl Formate Using Methanol. ACS Sustain. Chem. Eng. 2019, 7, 12270–12280. [Google Scholar] [CrossRef]
  2. Li, X.; Yu, J.; Jaroniec, M.; Chen, X. Cocatalysts for Selective Photoreduction of CO2 into Solar Fuels. Chem. Rev. 2019, 119, 3962–4179. [Google Scholar] [CrossRef] [PubMed]
  3. Zheng, Y.; Zhang, L.; Guan, J.; Qian, S.; Zhang, Z.; Ngaw, C.K.; Wan, S.; Wang, S.; Lin, J.; Wang, Y. Controlled Synthesis of Cu0/Cu2O for Efficient Photothermal Catalytic Conversion of CO2 and H2O. ACS Sustain. Chem. Eng. 2021, 9, 1754–1761. [Google Scholar] [CrossRef]
  4. Zhang, L.; Zhang, L.; Chen, Y.; Zheng, Y.; Guo, J.; Wan, S.; Wang, S.; Ngaw, C.K.; Lin, J.; Wang, Y. CdS/ZnO: A Multipronged Approach for Efficient Reduction of Carbon Dioxide under Visible Light Irradiation. ACS Sustain. Chem. Eng. 2020, 8, 5270–5277. [Google Scholar] [CrossRef]
  5. Mousavi, M.; Habibi-Yangjeh, A.; Pouran, S.R. Review on magnetically separable graphitic carbon nitride-based nanocomposites as promising visible-light-driven photocatalysts. J. Mater. Sci. Mater. Electron. 2018, 29, 1719–1747. [Google Scholar] [CrossRef]
  6. Li, Y.; Ruan, Z.; He, Y.; Li, J.; Li, K.; Jiang, Y.; Xu, X.; Yuan, Y.; Lin, K. In situfabrication of hierarchically porous g-C3N4 and understanding on its enhanced photocatalytic activity based on energy absorption. Appl. Catal. B Environ. 2018, 236, 64–75. [Google Scholar] [CrossRef]
  7. Bhowmik, S.; Phukan, S.J.; Sah, N.K.; Roy, M.; Garai, S.; Iyer, P.K. Review of Graphitic Carbon Nitride and Its Composite Catalysts for Selective Reduction of CO2. ACS Appl. Nano Mater. 2021, 4, 12845–12890. [Google Scholar] [CrossRef]
  8. Ong, W.-J.; Tan, L.-L.; Ng, Y.H.; Yong, S.-T.; Chai, S.-P. Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer to Achieving Sustainability? Chem. Rev. 2016, 116, 7159–7329. [Google Scholar] [CrossRef]
  9. Singh, P.; Yadav, R.K.; Kumar, K.; Lee, Y.; Gupta, A.K.; Kumar, K.; Yadav, B.C.; Singh, S.N.; Dwivedi, D.K.; Nam, S.-H.; et al. Eosin-Y and sulfur-codoped g-C3N4 composite for photocatalytic applications: The regeneration of NADH/NADPH and the oxidation of sulfide to sulfoxide. Catal. Sci. Technol. 2021, 11, 6401–6410. [Google Scholar] [CrossRef]
  10. Chen, D.; Wang, K.; Ren, T.; Ding, H.; Zhu, Y. Synthesis and characterization of the ZnO/mpg-C3N4 heterojunction photocatalyst with enhanced visible light photoactivity. Dalton Trans. 2014, 43, 13105–13114. [Google Scholar] [CrossRef]
  11. Yu, J.; Wang, S.; Cheng, B.; Lin, Z.; Huang, F. Noble metal-free Ni(OH)2–g-C3N4 composite photocatalyst with enhanced visible-light photocatalytic H2-production activity. Catal. Sci. Technol. 2013, 3, 1782–1789. [Google Scholar] [CrossRef]
  12. Wang, X.; Chen, X.; Thomas, A.; Fu, X.; Antonietti, M. Metal-Containing Carbon Nitride Compounds: A New Functional Organic–Metal Hybrid Material. Adv. Mater. 2009, 21, 1609–1612. [Google Scholar] [CrossRef]
  13. Ding, Z.; Chen, X.; Antonietti, M.; Wang, X. Synthesis of Transition Metal-Modified Carbon Nitride Polymers for Selective Hydrocarbon Oxidation. ChemSusChem 2011, 4, 274–281. [Google Scholar] [CrossRef]
  14. Samanta, S.; Martha, S.; Parida, K. Facile Synthesis of Au/g-C3N4 Nanocomposites: An Inorganic/Organic Hybrid Plasmonic Photocatalyst with Enhanced Hydrogen Gas Evolution under Visible-Light Irradiation. ChemCatChem 2014, 6, 1453–1462. [Google Scholar]
  15. Linic, S.; Christopher, P.; Ingram, D.B. Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy. Nat. Mater. 2011, 10, 911–921. [Google Scholar] [CrossRef] [PubMed]
  16. Zhang, X.-S.; Hu, J.-Y.; Jiang, H. Facile modification of a graphitic carbon nitride catalyst to improve its photoreactivity under visible light irradiation. Chem. Eng. J. 2014, 256, 230–237. [Google Scholar] [CrossRef]
  17. Zhang, J.; Zhang, M.; Yang, C.; Wang, X. Nanospherical Carbon Nitride Frameworks with Sharp Edges Accelerating Charge Collection and Separation at a Soft Photocatalytic Interface. Adv. Mater. 2014, 26, 4121–4126. [Google Scholar] [CrossRef] [PubMed]
  18. Nayak, S.; Mohapatra, L.; Parida, K. Visible light-driven novel g-C3N4/NiFe-LDH composite photocatalyst with enhanced photocatalytic activity towards water oxidation and reduction reaction. J. Mater. Chem. A 2015, 3, 18622–18635. [Google Scholar] [CrossRef]
  19. Li, H.; Liu, Y.; Cui, Y.; Zhang, W.; Fu, C.; Wang, X. Facile synthesis and enhanced visible-light photoactivity of DyVO2/g-C3N4I composite semiconductors. Appl. Catal. B Environ. 2016, 183, 426–432. [Google Scholar] [CrossRef]
  20. Yao, L.; Wei, D.; Ni, Y.; Yan, D.; Hu, C. Surface localization of CdZnS quantum dots onto 2D g-C3N4 ultrathin microribbons: Highly efficient visible light-induced H2-generation. Nano Energy 2016, 26, 248–256. [Google Scholar] [CrossRef]
  21. Kumar, P.; Laishram, D.; Sharma, R.K.; Vinu, A.; Hu, J.; Kibria, M.G. Boosting Photocatalytic Activity Using Carbon Nitride Based 2D/2D van der Waals Heterojunctions. Chem. Mater. 2021, 33, 9012–9092. [Google Scholar] [CrossRef]
  22. Zhao, Y.; Zhao, F.; Wang, X.; Xu, C.; Zhang, Z.; Shi, G.; Qu, L. Graphitic Carbon Nitride Nanoribbons: Graphene-Assisted Formation and Synergic Function for Highly Efficient Hydrogen Evolution. Angew. Chem. Int. Ed. 2014, 53, 13934–13939. [Google Scholar] [CrossRef] [PubMed]
  23. Wang, W.; Zhang, H.; Zhang, S.; Liu, Y.; Wang, G.; Sun, C.; Zhao, H. Potassium-Ion-Assisted Regeneration of Active Cyano Groups in Carbon Nitride Nanoribbons: Visible-Light-Driven Photocatalytic Nitrogen Reduction. Angew. Chem. Int. Ed. 2019, 58, 16644–16650. [Google Scholar] [CrossRef]
  24. Xiao, Y.; Tian, G.; Li, W.; Xie, Y.; Jiang, B.; Tian, C.; Zhao, D.; Fu, H. Molecule Self-Assembly Synthesis of Porous Few-Layer Carbon Nitride for Highly Efficient Photoredox Catalysis. J. Am. Chem. Soc. 2019, 141, 2508–2515. [Google Scholar] [CrossRef] [PubMed]
  25. Cui, J.; Qi, D.; Wang, X. Research on the techniques of ultrasound-assisted liquid-phase peeling, thermal oxidation peeling and acid-base chemical peeling for ultra-thin graphite carbon nitride nanosheets. Ultrason. Sonochem. 2018, 48, 181–187. [Google Scholar] [CrossRef] [PubMed]
  26. Fu, J.; Zhu, L.; Jiang, K.; Liu, K.; Wang, Z.; Qiu, X.; Li, H.; Hu, J.; Pan, H.; Lu, Y.-R.; et al. Activation of CO2 on graphitic carbon nitride supported single-atom cobalt sites. Chem. Eng. J. 2021, 415, 128982. [Google Scholar] [CrossRef]
  27. Yu, H.; Shi, R.; Zhao, Y.; Bian, T.; Zhao, Y.; Zhou, C.; Waterhouse, G.I.N.; Wu, L.-Z.; Tung, C.-H.; Zhang, T. Alkali-Assisted Synthesis of Nitrogen Deficient Graphitic Carbon Nitride with Tunable Band Structures for Efficient Visible-Light-Driven Hydrogen Evolution. Adv. Mater. 2017, 29, 1605148. [Google Scholar] [CrossRef]
  28. Yao, G.; Liu, Y.; Liu, J.; Xu, Y. Facile Synthesis of Porous g-C3N4 with Enhanced Visible-Light Photoactivity. Molecules 2022, 27, 1754. [Google Scholar] [CrossRef]
  29. Guo, S.; Deng, Z.; Li, M.; Jiang, B.; Tian, C.; Pan, Q.; Fu, H. Phosphorus-Doped Carbon Nitride Tubes with a Layered Micro-nanostructure for Enhanced Visible-Light Photocatalytic Hydrogen Evolution. Angew. Chem. Int. Ed. 2016, 55, 1830–1834. [Google Scholar] [CrossRef]
  30. Pandi, K.; Lakhera, S.K.; Neppolian, B. Facile synthesis of nitrogen deficient graphitic carbon nitride for photocatalytic hydrogen production activity. Mater. Lett. 2021, 303, 130467. [Google Scholar] [CrossRef]
  31. Iqbal, W.; Qiu, B.; Lei, J.; Wang, L.; Zhang, J.; Anpo, M. One-step large-scale highly active g-C3N4 nanosheets for efficient sunlight-driven photocatalytic hydrogen production. Dalton Trans. 2017, 46, 10678–10684. [Google Scholar] [CrossRef] [PubMed]
  32. Tian, N.; Zhang, Y.; Li, X.; Xiao, K.; Du, X.; Dong, F.; Waterhouse, G.I.N.; Zhang, T.; Huang, H. Precursor-reforming protocol to 3D mesoporous g-C3N4 established by ultrathin self-doped nanosheets for superior hydrogen evolution. Nano Energy 2017, 38, 72–81. [Google Scholar] [CrossRef]
  33. Huang, H.; Xiao, K.; Tian, N.; Dong, F.; Zhang, T.; Du, X.; Zhang, Y. Template-free precursor-surface-etching route to porous, thin g-C3N4 nanosheets for enhancing photocatalytic reduction and oxidation activity. J. Mater. Chem. A 2017, 5, 17452–17463. [Google Scholar] [CrossRef]
  34. Huang, S.; Yi, H.; Zhang, L.; Jin, Z.; Long, Y.; Zhang, Y.; Liao, Q.; Na, J.; Cui, H.; Ruan, S.; et al. Non-precious molybdenum nanospheres as a novel cocatalyst for full-spectrum-driven photocatalytic CO2 reforming to CH4. J. Hazard. Mater. 2020, 393, 122324. [Google Scholar] [CrossRef]
  35. Hong, J.; Zhang, W.; Ren, J.; Xu, R. Photocatalytic reduction of CO2: A brief review on product analysis and systematic methods. Anal. Methods 2013, 5, 1086–1097. [Google Scholar] [CrossRef]
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Figure 1. Schematic diagram on the fabrication of PN-g-C3N4 photocatalyst.
Figure 1. Schematic diagram on the fabrication of PN-g-C3N4 photocatalyst.
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Figure 2. SEM images of PN-g-C3N4 (a,b) and g-C3N4 (c,d) samples.
Figure 2. SEM images of PN-g-C3N4 (a,b) and g-C3N4 (c,d) samples.
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Figure 3. N2 adsorption/desorption isotherms (a) and BJH pore size distribution of g-C3N4 and PN-g-C3N4 (b).
Figure 3. N2 adsorption/desorption isotherms (a) and BJH pore size distribution of g-C3N4 and PN-g-C3N4 (b).
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Figure 4. FTIR spectra of g-C3N4 and PN-g-C3N4 samples.
Figure 4. FTIR spectra of g-C3N4 and PN-g-C3N4 samples.
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Figure 5. UV-Vis DRS (a) and band gaps (b) of g-C3N4 and PN-g-C3N4 samples.
Figure 5. UV-Vis DRS (a) and band gaps (b) of g-C3N4 and PN-g-C3N4 samples.
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Figure 6. XRD spectra (a), XPS survey spectra (b), high-resolution C1s (c), and N1s (d) of g-C3N4 and PN-g-C3N4.
Figure 6. XRD spectra (a), XPS survey spectra (b), high-resolution C1s (c), and N1s (d) of g-C3N4 and PN-g-C3N4.
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Figure 7. (a) Photocatalytic activity of CO2 reduction of g-C3N4 and PN-g-C3N4 samples under visible light illumination and simulated sunlight with controls. (b) Photocatalytic cycle test of PN-g-C3N4.
Figure 7. (a) Photocatalytic activity of CO2 reduction of g-C3N4 and PN-g-C3N4 samples under visible light illumination and simulated sunlight with controls. (b) Photocatalytic cycle test of PN-g-C3N4.
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Figure 8. Transient photocurrent response (a), PL spectra (b), Valence band XPS spectra (c), and the Mott–Schottky plot (d) of g-C3N4 and PN-g-C3N4 samples.
Figure 8. Transient photocurrent response (a), PL spectra (b), Valence band XPS spectra (c), and the Mott–Schottky plot (d) of g-C3N4 and PN-g-C3N4 samples.
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Figure 9. The schematic illustration of the band gap structures of g-C3N4 and PN-g-C3N4 samples.
Figure 9. The schematic illustration of the band gap structures of g-C3N4 and PN-g-C3N4 samples.
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Figure 10. A possible photocatalytic CO2 reduction mechanism for CO production.
Figure 10. A possible photocatalytic CO2 reduction mechanism for CO production.
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Jiang, Z.; Shen, Y.; You, Y. Synthesis of Porous Carbon Nitride Nanobelts for Efficient Photocatalytic Reduction of CO2. Molecules 2022, 27, 6054. https://doi.org/10.3390/molecules27186054

AMA Style

Jiang Z, Shen Y, You Y. Synthesis of Porous Carbon Nitride Nanobelts for Efficient Photocatalytic Reduction of CO2. Molecules. 2022; 27(18):6054. https://doi.org/10.3390/molecules27186054

Chicago/Turabian Style

Jiang, Zhiqiang, Yirui Shen, and Yujing You. 2022. "Synthesis of Porous Carbon Nitride Nanobelts for Efficient Photocatalytic Reduction of CO2" Molecules 27, no. 18: 6054. https://doi.org/10.3390/molecules27186054

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