Mechanistic View of the Main Current Issues in Photocatalytic CO<sub>2</sub> Reduction

Fresno, Fernando; Villar‐García, Ignacio J.; Collado, Laura; Alfonso‐González, Elena; Reñones, Patricia; Barawi, Mariam; O’Shea, Víctor A. de la Peña

doi:10.1021/acs.jpclett.8b02336

Cited by 82 publications

(90 citation statements)

References 117 publications

(268 reference statements)

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“…In spite of its scientific interest, providing a route for CO2 valorization coupled to solar energy harnessing [143], it still faces a number of issues mainly related to the inherent difficulty associated to the stability and relative inertness of the CO2 molecule and to the complex nature of water oxidation. Indeed, this latter is in principle the preferred reaction to close the electron balance as Nature does in natural photosynthesis [144]. Among the different semiconductors that have been reported as CO2 reduction photocatalysts [145][146][147], ferrite-based ones do not play a prominent role, even if some of these oxides have adequate band positions for some of the reactions involved in CO2 reduction [148].…”

Section: Introductionmentioning

confidence: 99%

Ferrite Materials for Photoassisted Environmental and Solar Fuels Applications

et al. 2019

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Ferrites are a large class of oxides containing Fe 3+ and at least another metal cation that have been investigated for and applied to a wide variety of fields ranging from mature technologies like circuitry, permanent magnets, magnetic recording and microwave devices to the most recent developments in areas like bioimaging, gas sensing, and photocatalysis. In the last respect, although ferrites have been less studied than other types of semiconductors, they present interesting properties such as visible light absorption, tuneable optoelectronic properties and high chemical and photochemical stability. The versatility of their chemical composition and of their crystallographic structure opened a playground for developing new catalysts with enhanced efficiency. This article reviews the recent development of the application of ferrites to photoassisted processes for environmental remediation and for the synthesis of solar fuels. Applications in the photocatalytic degradation of pollutants in water and air, photo-Fenton, and solar fuels production, via photocatalytic and photoelectrochemical water splitting and CO2 reduction, are reviewed paying special attention to the relationships between the physico-chemical characteristics of the ferrite materials and their photo-activated performance.

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Section: Introductionmentioning

confidence: 99%

Ferrite Materials for Photoassisted Environmental and Solar Fuels Applications

et al. 2019

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“…The lowered Δ E VO is in accordance with the experimental observation that the abundance of Vo in TiO 2 is improved after the modification of CuO x , and sometimes Vo could even be induced by light irradiation as the value of Δ E VO is much smaller than the band gap mostly detected in CuO x /TiO 2 . 1 , 25 …”

Section: Results and Discussionmentioning

confidence: 99%

Mechanistic Understanding on the Role of Cu Species over the CuO_x/TiO₂ Catalyst for CO₂ Photoreduction

et al. 2020

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Incorporation of earth-abundant Cu is one of the most important approaches to improve the practicability of TiO 2 for photoreduction of CO 2 into value-added solar fuels. However, the molecular insight on the role of Cu is complicated and far from understood. We performed a first principle calculation on the anatase (101) surface modified by a single Cu atom deposited on the surface (Cu S ) or doped in the lattice (Cu L ). It is demonstrated the Cu L is clearly more stable than the Cu S and could promote the formation of oxygen vacancy (Vo) greatly. The Cu S plays a role of donor, while the Cu L is electronically deficient and becomes a global electron trapper. If a Vo is introduced, the excess electrons would immigrate to the empty gap state of the Cu L and make it half-filled in some case, which implies its metallic characters and improved conductivity; meanwhile, the formation of Ti 3+ is suppressed. Judging from the adsorption energies, it is the Vo that primarily improves the adsorption of CO 2 in both linear and bent states, and the Cu S could hardly stabilize CO 2 more, while the promotion effect of Vo could even be counteracted by the Cu L due to its electronic deficiency. The reduction pathways (CO 2 * → CO* + O*) show that, with the assistance of the Cu S , linear CO 2 could directly transform into the carbonate-like geometry vertically binding to the surface, and the intermediate configuration of the bent CO 2 horizontally bridging the Vo could be successfully skipped. Therefore, the barrier of the rate-determining transformation could be lowered from 0.75 to 0.39 eV. Furthermore, it is found the strong adsorption of the produced CO by the Cu S might retard the smooth going of the catalytic process.

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“…Several mechanisms, all involving radical intermediates, have been proposed for CO 2 photoreduction. 22,51 Sulphates or species arising from radical scavenging yielding SO 4 c À species thus acting as charge carrier trap and competing with water oxidation (Fig. 10).…”

Section: Characterization and Properties Of Mixed Metal Oxidesmentioning

confidence: 99%

“…CO 2 photoreduction faces the challenge of low efficiency but also the deactivation of the photocatalyst. 22 Deactivation of the photocatalyst has been reported, especially when production data is collected in continuous ow setups, for CO 2 photoreduction by a growing number of authors. [23][24][25][26][27][28][29][30][31][32] Possible explanations for deactivation include: photocatalyst poisoning due to irreversible adsorption of reaction intermediates; sintering and agglomeration of the photocatalyst metal active sites and loss of active reaction sites that include oxygen vacancies, surface hydroxyls and Ti 3+ sites.…”

Section: Introductionmentioning

confidence: 99%

“…[23][24][25][26][27][28][29][30][31][32] Possible explanations for deactivation include: photocatalyst poisoning due to irreversible adsorption of reaction intermediates; sintering and agglomeration of the photocatalyst metal active sites and loss of active reaction sites that include oxygen vacancies, surface hydroxyls and Ti 3+ sites. 22 To develop CO 2 photoreduction, low efficiency and deactivation of the photocatalyst need to be addressed. In a closely related eld of photocatalytic oxidation, radical scavenging of the reactive oxygen species as hydroxyl radicals have been found to lead to deactivation.…”

Section: Introductionmentioning

confidence: 99%

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