Photocatalytic Reduction of Low Concentration of CO<sub>2</sub>

Nakajima, Takehiko; Tamaki, Yusuke; Ueno, Kazunori; Kato, Eishiro; Nishikawa, Tetsuya; Ohkubo, Kei; Yamazaki, Yasuomi; Morimoto, Tatsuki; Ishitani, Osamu

doi:10.1021/jacs.6b08824

Cited by 196 publications

(149 citation statements)

References 23 publications

(39 reference statements)

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“…[17] Compared to the widely investigated visiblelight photocatalysts containing metal, such as metal oxides, sulfides, and oxynitrides, a metal free polymeric graphitic carbon nitride (gC 3 N 4 ) as a prom ising photocatalyst has received great attention in the field of sustainable energy production for CO 2 conversion and H 2 evo lution, owing to its suitable energy bandgap (2.7 eV), high sta bility and unique surface properties. It is clearly demonstrated that the as-prepared amount-optimized nanocomposite exhibits exceptional visible-light photocatalytic activities for CO 2 conversion to CH 4 and for H 2 evolution, respectively by ≈28-time (140 µmol g −1 h −1 ) and ≈31-time (313 µmol g −1 h −1 ) enhancement compared to the widely accepted outstanding g-C 3 N 4 prepared with urea as the raw material, along with the calculated quantum efficiencies of ≈4.92% and 2.78% at 420 nm wavelength. It is clearly demonstrated that the as-prepared amount-optimized nanocomposite exhibits exceptional visible-light photocatalytic activities for CO 2 conversion to CH 4 and for H 2 evolution, respectively by ≈28-time (140 µmol g −1 h −1 ) and ≈31-time (313 µmol g −1 h −1 ) enhancement compared to the widely accepted outstanding g-C 3 N 4 prepared with urea as the raw material, along with the calculated quantum efficiencies of ≈4.92% and 2.78% at 420 nm wavelength.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Large Surface‐Area g‐C₃N₄ Comodified with MnO_x and Au‐TiO₂ as Efficient Visible‐Light Photocatalysts for Fuel Production

Raziq

Sun

Wang

et al. 2017

Advanced Energy Materials

164

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Herein, this study successfully fabricates porous g‐C3N4‐based nanocomposites by decorating sheet‐like nanostructured MnOx and subsequently coupling Au‐modified nanocrystalline TiO2. It is clearly demonstrated that the as‐prepared amount‐optimized nanocomposite exhibits exceptional visible‐light photocatalytic activities for CO2 conversion to CH4 and for H2 evolution, respectively by ≈28‐time (140 µmol g−1 h−1) and ≈31‐time (313 µmol g−1 h−1) enhancement compared to the widely accepted outstanding g‐C3N4 prepared with urea as the raw material, along with the calculated quantum efficiencies of ≈4.92% and 2.78% at 420 nm wavelength. It is confirmed mainly based on the steady‐state surface photovoltage spectra, transient‐state surface photovoltage responses, fluorescence spectra related to the produced •OH amount, and electrochemical reduction curves that the exceptional photoactivities are comprehensively attributed to the large surface area (85.5 m2 g−1) due to the porous structure, to the greatly enhanced charge separation and to the introduced catalytic functions to the carrier‐related redox reactions by decorating MnOx and coupling Au‐TiO2, respectively, to modulate holes and electrons. Moreover, it is suggested mainly based on the photocatalytic experiments of CO2 reduction with isotope 13CO2 and D2O that the produced •CO2 and •H as active radicals would be dominant to initiate the conversion of CO2 to CH4.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Large Surface‐Area g‐C₃N₄ Comodified with MnO_x and Au‐TiO₂ as Efficient Visible‐Light Photocatalysts for Fuel Production

Raziq

Sun

Wang

et al. 2017

Advanced Energy Materials

164

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“…Therefore, CO 2 reduction at low concentration is also an important topic. [40] Surely, the above discussion is mostly based on CO 2 reduction with H 2 O in solution. If the photocatalytic reduction proceeds in the gas phase, especially with H 2 as the hydrogen source, the reduction efficiency should be improved, and the products can be mostly selected.…”

Section: Uv Light-driven Photocatalysismentioning

confidence: 99%

Full‐Spectrum Solar‐Light‐Activated Photocatalysts for Light–Chemical Energy Conversion

Wang

Sang

et al. 2017

Advanced Energy Materials

242

116

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photocatalysis based on semiconductors represents another route for light energy conversion. This route endows the direct conversion of light energy into oxidation and reduction energy via charge carriers (electrons and holes) generated in the semiconductors. For instance, the photocatalytic degradation of harmful and toxic organic substances, dyes, and chemicals has been considered to be a suitable candidate for removing organic pollution from water, [5][6][7][8] where photooxidation dominates the degradation of the organic molecules. The full process of photocatalytic water splitting into H 2 and O 2 is believed to be promising for generating renewable and green energy, [9,10] and the process includes the photoreduction and photooxidation of water, respectively. The photocatalytic reduction of CO 2 can convert solar energy into chemical energy, stored as CH 4 , CO, CH 3 OH, etc. [11][12][13] These processes can help reduce the pressure of the global warming crisis and supply usable renewable energy. Due to the precise control of photocatalytic reduction and oxidation, photocatalytic molecular synthesis has also attracted much interest, which provides a sustainable pathway for green synthesis. [14][15][16] For an efficient photocatalytic process, solar light harvesting and a redox process based on photogenerated charge carriers are essential steps. Solar light harvesting consists of light absorption and charge carrier excitation steps, which can be expressed as the light utilization efficiency. The efficiency determines the total energy converted from solar light and is mostly determined by the band structure of the semiconductor applied to the photocatalytic process.The photocatalytic process has been extensively studied by examining the response of photocatalysts to UV light, due to its relatively high photonic energy. As is well known, UV light energy amounts to no more than 5% of the solar light energy. Visible light and near-infrared (NIR) light contain approximately 90% of the solar light energy. To utilize solar light in order to solve the environmental and energy crisis, visible light and NIR-light-activated photocatalysts are essential. For decades, many studies have focused on expanding the range over which a photocatalyst can utilize the solar light spectrum. In addition, there are several good reviews summarizing recent progress on UV-vis-light-activated photocatalysts, as well as strategies to improve the photocatalytic efficiency. [17][18][19][20] As is well known, the photonic energy of visible light is low, and that of NIR light is even lower. Photoinduced redox requires an initial amount of energy to activate the process; however, NIR photonic energy may be too low to realize photoinduced The realization of light-chemical energy conversion using solar light is an ideal goal in renewable energy studies. Many reports are concerned with extracting energy from solar light and the use/storage of the converted energy. Due to the progress in solar light absorption with various photocatalysts, the vari...

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“…Thus, a catalyst which operates under reduced CO 2 concentrations is highly desirable [30]. To prove the reactivity of each catalyst with reduced CO 2 concentrations, ambient atmosphere (air) was added as the makeup gas.…”

Section: Catalyst Sensitivity: Air Concentrationmentioning

confidence: 99%

A Robust Pyridyl-NHC-Ligated Rhenium Photocatalyst for CO2 Reduction in the Presence of Water and Oxygen

et al. 2018

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Re(pyNHC-PhCF 3 )(CO) 3 Br is a highly active photocatalyst for CO 2 reduction. The PhCF 3 derivative was previously empirically shown to be a robust catalyst. Here, the role of the PhCF 3 group is probed computationally and the robust nature of this catalyst is analyzed with regard to the presence of water and oxygen introduced in controlled amounts during the photocatalytic reduction of CO 2 to CO with visible light. This complex was found to work well from 0-1% water concentration reproducibly; however, trace amounts of water were required for benchmark Re(bpy)(CO) 3 Cl to give reproducible reactivity. When ambient air is added to the reaction mixture, the NHC complex was found to retain substantial performance (~50% of optimized reactivity) at up to 40% ambient atmosphere and 60% CO 2 while the Re(bpy)(CO) 3 Cl complex was found to give a dramatically reduced CO 2 reduction reactivity upon introduction of ambient atmosphere. Through the use of time-correlated single photon counting studies and prior electrochemical results, we reasoned that this enhanced catalyst resilience is due to a mechanistic difference between the NHC-and bpy-based catalysts. These results highlight an important feature of this NHC-ligated catalyst: substantially enhanced stability toward common reaction contaminates.

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Photocatalytic Reduction of Low Concentration of CO₂

Cited by 196 publications

References 23 publications

Synthesis of Large Surface‐Area g‐C₃N₄ Comodified with MnO_x and Au‐TiO₂ as Efficient Visible‐Light Photocatalysts for Fuel Production

Synthesis of Large Surface‐Area g‐C₃N₄ Comodified with MnO_x and Au‐TiO₂ as Efficient Visible‐Light Photocatalysts for Fuel Production

Full‐Spectrum Solar‐Light‐Activated Photocatalysts for Light–Chemical Energy Conversion

A Robust Pyridyl-NHC-Ligated Rhenium Photocatalyst for CO2 Reduction in the Presence of Water and Oxygen

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Photocatalytic Reduction of Low Concentration of CO2

Cited by 196 publications

References 23 publications

Synthesis of Large Surface‐Area g‐C3N4 Comodified with MnOx and Au‐TiO2 as Efficient Visible‐Light Photocatalysts for Fuel Production

Synthesis of Large Surface‐Area g‐C3N4 Comodified with MnOx and Au‐TiO2 as Efficient Visible‐Light Photocatalysts for Fuel Production

Full‐Spectrum Solar‐Light‐Activated Photocatalysts for Light–Chemical Energy Conversion

A Robust Pyridyl-NHC-Ligated Rhenium Photocatalyst for CO2 Reduction in the Presence of Water and Oxygen

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Product

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Photocatalytic Reduction of Low Concentration of CO₂

Synthesis of Large Surface‐Area g‐C₃N₄ Comodified with MnO_x and Au‐TiO₂ as Efficient Visible‐Light Photocatalysts for Fuel Production

Synthesis of Large Surface‐Area g‐C₃N₄ Comodified with MnO_x and Au‐TiO₂ as Efficient Visible‐Light Photocatalysts for Fuel Production