An Amorphous Carbon Nitride Photocatalyst with Greatly Extended Visible‐Light‐Responsive Range for Photocatalytic Hydrogen Generation

Kang, Yuyang; Yang, Yongqiang; Yin, Lichang; Kang, Xiangdong; Liu, Gang; Cheng, Hui‐Ming

doi:10.1002/adma.201501939

Cited by 837 publications

(518 citation statements)

References 38 publications

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“…31 Additionally, a reduced optical gap of PCN at 1.90 eV was reported for an amorphous PCN. 32 In order to be suitable for practical applications, it has been predicted that E opt g has to lie between 1.8 and 2.1 eV to meet the targeted ∼10 % solar to hydrogen efficiency. 33 Hence, to further exploit the photocatalytic efficiency of PCNs, an understanding of the underlying parameters affecting the optical properties of PCNs is highly desirable.…”

Section: Refining the Methodologymentioning

confidence: 99%

Shining Light on Carbon Nitrides: Leveraging Temperature To Understand Optical Gap Variations

Melissen

Bahers

et al. 2018

Chem. Mater.

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Polymeric carbon nitride (PCN)-based materials have opened new research avenues in the photocatalytic field. The understanding of parameters underlying the optical properties of PCNs is critical to improve their performance. Herein, the optical properties of PCNs are investigated with a combination of Time-Dependent Density Functional Theory (TD-DFT) calculations and laboratory characterizations, including Variable Temperature (VT)-XRD, VT-UV-Vis and VT-IR techniques, on samples prepared using a broad range of synthesis temperatures. Upon increasing the synthesis temperature from 390 to 600°C, the optical gap E opt g (eV) narrows from 2.92 to 2.67, and on further increasing the synthesis temperature to 700°C, widens to 3.03 and another absorption at ∼2.2 eV is observed. The TD-DFT calculations show that E opt g of PCNs converges rapidly with heptazine oligomer size, indicating localized photophysics behavior and justifying a molecular approach. Calculations exploring geometrical variations upon increasing the temperature at which the optical properties were determined revealed that the net effect of these variations were limited, suggesting a vibrational origin of the observed decrease in the gap. The absorption at ∼2.2 eV is tentatively attributed to fully polymerized graphitic PCN oligomers as suggested by the excitation wavelength-dependent photoluminescence emission behavior. The results provide novel insights into the optical properties of PCNs, providing directions for the development of the next generation of PCN-based photocatalysts with optimal light harvesting abilities.

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Section: Refining the Methodologymentioning

confidence: 99%

Shining Light on Carbon Nitrides: Leveraging Temperature To Understand Optical Gap Variations

Melissen

Bahers

et al. 2018

Chem. Mater.

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“…The increase in the band gap by 0.10 eV improves the redox ability of the charge carriers generated in the CN nanosheets. 40 This result was further conrmed by the blue-shi in its uorescence emission peak in Fig. 6b; this could be attributed to the quantum connement effect.…”

Section: Optical Propertiesmentioning

confidence: 86%

“…However, the two sharp peaks become very weak in the U-N pattern, which demonstrate the absence of long-range order in the atomic arrangements. 40,41 We may infer the multiple effects of too many gas bubbles, which are produced during thermal condensation of urea, and the additional N 2 signicantly disrupts the longrange atomic order in both the perpendicular and parallel directions to the g-C 3 N 4 layers. Aer stopping the addition of N 2 , the self-producing atmosphere originates from the interior of the reaction system.…”

Section: Structural Characteristicsmentioning

confidence: 99%

Highly efficient pollutant removal of graphitic carbon nitride by the synergistic effect of adsorption and photocatalytic degradation

et al. 2018

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Environmental remediation based on semiconducting materials offers a green solution for pollution control in water. Herein, we report a novel graphitic carbon nitride (g-C 3 N 4 ) by one-step polycondensation of urea.The novel g-C 3 N 4 material with a surface area of 114 m 2 g À1 allowed the repetitive adsorption of the rhodamine B (RhB) dye and facilitated its complete photocatalytic degradation upon light irradiation in 20 min. This study provides new insights into the fabrication of g-C 3 N 4 -based materials and facilitates their potential application in the synergistic removal of harmful organic pollutants in the field of water purification.

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“…The covalent bonds are more resistant to rupture than vdW and hydrogen bonds that offer a possibility of disrupting long‐range, but keeping short‐range, atomic order for homogeneous amorphization upon heating PCN at elevated temperature. Kang et al reported ACN with a band gap of 1.90 eV 25. Following this, we worked on ameliorating the charge transfer kinetics of ACN to overcome its low quantum yield (<0.5%) for hydrogen production 54…”

Section: Selective Techniques For Tuning Intrinsic Properties Of Cnmentioning

confidence: 95%

“…Besides polycrystalline GCN, amorphous carbon nitride (ACN) has also been reported to be a promising photocatalyst 25, 26, 27. Varying the C/N ratio, two eminent derivatives of carbon nitride, namely, C 2 N28 and C 3 N29 have been reported, which might also possibly be used as a photocatalyst.…”

Section: A Brief Overview Of Carbon Nitridesmentioning

confidence: 99%

Tuning the Intrinsic Properties of Carbon Nitride for High Quantum Yield Photocatalytic Hydrogen Production

2018

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The low quantum yield of photocatalytic hydrogen production in carbon nitride (CN) has been improved upon via the modulation of both the extrinsic and intrinsic properties of the material. Although the modification of extrinsic properties has been widely investigated in the past, recently there has been growing interest in the alteration of intrinsic properties. Refining the intrinsic properties of CN provides flexibility in controlling the charge transport and selectivity in photoredox reactions, and therefore makes available a pathway toward superior photocatalytic performance. An analysis of recent progress in tuning the intrinsic photophysical properties of CN facilitates an assessment of the goals, achievements, and gaps. This article is intended to serve this purpose. Therefore, selected techniques and mechanisms of the tuning of intrinsic properties of CN are critically discussed here. This article concludes with a recommendation of the issues that need to be considered for the further enhancement in the quantum efficiency of CN photocatalysts.

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An Amorphous Carbon Nitride Photocatalyst with Greatly Extended Visible‐Light‐Responsive Range for Photocatalytic Hydrogen Generation

Cited by 837 publications

References 38 publications

Shining Light on Carbon Nitrides: Leveraging Temperature To Understand Optical Gap Variations

Shining Light on Carbon Nitrides: Leveraging Temperature To Understand Optical Gap Variations

Highly efficient pollutant removal of graphitic carbon nitride by the synergistic effect of adsorption and photocatalytic degradation

Tuning the Intrinsic Properties of Carbon Nitride for High Quantum Yield Photocatalytic Hydrogen Production

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