On the general mechanism of photocatalytic reduction of CO2

Karamian, Elham; Sharifnia, Shahram

doi:10.1016/j.jcou.2016.07.004

Cited by 233 publications

(126 citation statements)

References 116 publications

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“…Among these, hydrogen and CO are produced by photoreforming of the newly-reduced organic compounds. Furthermore, in similar photocatalytic systems [61,65,66], it is reported that the reaction is triggered by the formation of peroxocarbonate species, which are reduced to formic acid, formaldehyde, and methanol afterwards. Due to the higher H 2 O/CO 2 ratio, it is plausible that ·CO 2 − undergoes hydrogenation faster than deoxygenation, leading to all those products found in the liquid phase.…”

Section: Liquid Phase Photocatalytic Resultsmentioning

confidence: 99%

“…Methane derives from complete carbon dioxide photoreduction and no trace of other carbonaceous species, like CO or formaldehyde, were detected. Karamian and co-workers [61], reported that, in most cases, in gaseous systems CO is the first intermediate product of CO 2 photoreduction by water vapour. However, reaction conditions, and in particular temperature, irradiance, and reaction time, can modify the reaction pathway and, thus, product distribution.…”

Section: Vapour Phase Photocatalytic Resultsmentioning

confidence: 99%

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Liquid vs. Gas Phase CO2 Photoreduction Process: Which Is the Effect of the Reaction Medium?

et al. 2017

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Abstract:The use of carbon dioxide, the most concerning environmental issue of the 21st century, as a feedstock for fuels productions still represents an innovative, yet challenging, task for the scientific community. CO 2 photoreduction processes have the potential to transform this hazardous pollutant into important products for the energy industry (e.g., methane and methanol) employing a photocatalyst and light as the only energy input. In order to design an effective process, the high sustainability of this reaction should be matched with the perfect reaction conditions to allow the reactant, photocatalyst, and light source to come together: therefore, the choice of reaction conditions, and in particular its medium, is a crucial issue that needs to be investigated. Throughout this paper, a careful study of carbon dioxide photoreduction in liquid and vapour phases are reported, focusing on their effect on catalyst performances in terms of light harvesting, productivity, and selectivity. Different from most papers in the literature, catalytic tests were performed under extremely low light irradiance, in order to minimise the primary energy input, highlighting that this experimental variable has a great effect on the reaction pathway and, thus, product distribution.

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Section: Liquid Phase Photocatalytic Resultsmentioning

confidence: 99%

Section: Vapour Phase Photocatalytic Resultsmentioning

confidence: 99%

Liquid vs. Gas Phase CO2 Photoreduction Process: Which Is the Effect of the Reaction Medium?

et al. 2017

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“…If the reaction rates of stages (5) and (6) are smaller than that of stage (4), CO will be the main reduction product. This hypothesis (stage 4 faster than stages 5 and 6) is quite likely considering that, unlike CO formation, the production of CH 4 requires the existence of charge carriers (holes and electrons) ,…”

Section: Resultsmentioning

confidence: 99%

Improving the photo‐reduction of CO₂ to fuels with catalysts synthesized under high pressure: Cu/TiO₂

Camarillo

Tostón

Martínez

et al. 2017

J of Chemical Tech & Biotech

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BACKGROUND In previous studies the enhanced activity of TiO2‐based catalysts synthesized in supercritical medium for photocatalytic reduction of CO2 was proved. RESULTS In this study, Cu/TiO2 photocatalysts were synthesized by hydrothermal methods in supercritical CO2. Two titanium precursors [titanium tetraisopropoxide and diisopropoxititanium bis(acetylacetonate)], two alcohols (ethanol and isopropyl alcohol), and one metal precursor (Cu (II) acetylacetonate) were used in the synthesis. Catalysts produced showed improved properties in comparison with the commercial reference catalyst (Degussa P‐25, Evonik). CONCLUSIONS Specifically, it has been found that Cu/TiO2 catalysts may yield methane production rates 20 times larger than that of commercial TiO2 catalyst without diminishing CO production rate (about 5 times higher than that of commercial catalyst). This result has been mainly imputed to both the formation of oxygen vacancies during the synthesis in supercritical medium and the high capacity of copper to adsorb and activate CO2 molecules, while preventing CO molecules from reoxidation, and avoiding the competitive reaction of hydrogen formation. © 2017 Society of Chemical Industry

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“…The resulting electron-hole pairs may recombine in either the bulk of the semiconductor, or at the surface, with the associated energy released through either fluorescence or thermal excitation of the lattice (Step II); recombination is the primary process that limits photocatalyst efficiency after photon capture. Electrons (and holes) that migrate to the surface of the semiconductor and do not undergo rapid recombination may participate in various oxidation and reduction reactions with adsorbates such as water, oxygen, and other organic or inorganic species (Steps III and IV) [9,10,23,24]. These steps are summarized below and illustrated in Figure 2:…”

Section: Photocatalytic Mechanismsmentioning

confidence: 99%

g-C3N4-Based Nanomaterials for Visible Light-Driven Photocatalysis

2018

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Graphitic carbon nitride (g-C 3 N 4 ) is a promising material for photocatalytic applications such as solar fuels production through CO 2 reduction and water splitting, and environmental remediation through the degradation of organic pollutants. This promise reflects the advantageous photophysical properties of g-C 3 N 4 nanostructures, notably high surface area, quantum efficiency, interfacial charge separation and transport, and ease of modification through either composite formation or the incorporation of desirable surface functionalities. Here, we review recent progress in the synthesis and photocatalytic applications of diverse g-C 3 N 4 nanostructured materials, and highlight the physical basis underpinning their performance for each application. Potential new architectures, such as hierarchical or composite g-C 3 N 4 nanostructures, that may offer further performance enhancements in solar energy harvesting and conversion are also outlined.

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On the general mechanism of photocatalytic reduction of CO2

Cited by 233 publications

References 116 publications

Liquid vs. Gas Phase CO2 Photoreduction Process: Which Is the Effect of the Reaction Medium?

Liquid vs. Gas Phase CO2 Photoreduction Process: Which Is the Effect of the Reaction Medium?

Improving the photo‐reduction of CO₂ to fuels with catalysts synthesized under high pressure: Cu/TiO₂

g-C3N4-Based Nanomaterials for Visible Light-Driven Photocatalysis

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On the general mechanism of photocatalytic reduction of CO2

Cited by 233 publications

References 116 publications

Liquid vs. Gas Phase CO2 Photoreduction Process: Which Is the Effect of the Reaction Medium?

Liquid vs. Gas Phase CO2 Photoreduction Process: Which Is the Effect of the Reaction Medium?

Improving the photo‐reduction of CO2 to fuels with catalysts synthesized under high pressure: Cu/TiO2

g-C3N4-Based Nanomaterials for Visible Light-Driven Photocatalysis

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Improving the photo‐reduction of CO₂ to fuels with catalysts synthesized under high pressure: Cu/TiO₂