Chloride ion: A promising hole scavenger for photocatalytic hydrogen generation

Hippargi, Girivyankatesh; Mangrulkar, Priti A.; Chilkalwar, Anushree A.; Labhsetwar, Nitin; Rayalu, Sadhana

doi:10.1016/j.ijhydene.2017.12.179

Cited by 22 publications

(10 citation statements)

References 44 publications

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“…Distinct from organic ligands, the omnipresent inorganic anions generally influence the photoreductive dissolution of iron (hydr)oxides through modifying the surface structure and properties of the minerals, which subsequently change both the light absorption and Fe dissolution. ,, For example, in low pH environments, photoreductive dissolution of iron (hydr)oxides is enhanced in the presence of chloride, and clearly inhibited with sulfate, perchlorate and nitrate . It was believed that chloride ions can serve as hole scavengers to inhibit the recombination of photoinduced electrons and holes, and the resultant surplus electrons promote the reduction of Fe(III). , Benkelberg and Warneck suggested that the suppression of sulfate on photoreduction is due to the formation of solvent cage via coulomb field attraction between ferrous and sulfate, which suppresses the formation of free Fe 2+ . Perchlorate and nitrate are generally oxidizing acid ions and weak ligands, which can act as oxidizing agents and poor electron donors, resisting the photoreduction of Fe(III). , …”

Section: The Factors Affecting Photoreductive Dissolution Of Iron (Hy...mentioning

confidence: 99%

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Liu

Zhu

et al. 2022

ACS Earth Space Chem.

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Iron (hydr)oxides are the most abundant metal oxides, which are widespread on Earth’s surface in the major form of micro/nanoparticles. Dissolution of iron (hydr)oxides significantly controls their compositions on Earth’s surface and is a critical step for the global Fe cycling. Photoreductive dissolution of iron (hydr)oxides is recognized as one of the most important process for generating Fe2+ in surface water and is also a common pathway for transforming solar energy into chemical energy. This review article dissects the main characteristics of photoreductive dissolution of iron (hydr)oxides and discusses its geochemical and environmental significance. We categorize the mechanisms for photoreduction of iron (hydr)oxides into three types: reduction by intrinsic photogenerated electrons, reduction by ligand to metal electron transfer (LMCT), and reduction by direct injection of exogenous photoelectrons. The efficiency of photoreductive dissolution is constrained by both the structure of iron (hydr)oxides (e.g., crystal structure and particle size) and environmental conditions (e.g., light, pH, and concurrent chemicals). Therefore, different iron (hydr)oxides may exhibit quite distinctive photoreductive dissolution characteristics because of their unique crystal structures and physicochemical properties. Iron (hydr)oxides with low crystallinity (e.g., ferrihydrite, lepidocrocite) are subject to direct photoreductive dissolution, while those with high crystallinity (e.g., goethite, hematite) generally need ligands to proceed with photoreductive dissolution. The photoreductive dissolution of iron (hydr)oxides is involved in many important geochemical and environmental processes, such as the Fe availability to primary producers, the generation of reactive oxygen species, the transportation and fate of contaminants, and the phase transformation of iron (hydr)oxides. Given the ubiquitous occurrence of photoreductive dissolution of iron (hydr)oxides, this review will advance our understanding of the role of this process in Earth’s surface environments.

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Section: The Factors Affecting Photoreductive Dissolution Of Iron (Hy...mentioning

confidence: 99%

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Liu

Zhu

et al. 2022

ACS Earth Space Chem.

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“…A very limited number of researchers have investigated the influence of halogen based sacrificial donors on the efficiency of photocatalytic water splitting systems. For instance, Sadhana Rayalu and coworkers [27] have recently studied the effect of chloride ions (Cl -, released during HAuCl 4 photoreduction) as a sacrificial donor on the photocatalytic hydrogen production. In their study, Sadhana Rayalu and coworkers synthesized two Au/TiO 2 photocatalysts using two different routes, without and with the formation of Cl -.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Cathodically activated Au/TiO2 nanocomposite synthesized by a new facile solvothermal method: An efficient electrocatalyst with Pt-like activity for hydrogen generation

Mezni

Ibrahim

El‐Kemary

et al. 2018

Electrochimica Acta

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“…Based on the abovementioned results, we consider that it is correct for the mechanism of chloride-mediated reaction. When introducing chlorides on the synthesized materials, the formation of the intermediates such as HClO in the process of CO 2 reduction is more advantageous in kinetics than producing O 2 directly. ,− According to Huang et al, the activation energy for HClO formation is lower than that for water oxidation. Therefore, we can conclude that it is the decrease of activation energy that results in the increase of oxidation half reaction activity.…”

Section: Resultsmentioning

confidence: 99%

“…An efficient way to accelerate water oxidation is to explore a redox mediator that can change the reaction path. In this regard, chloride is proven to be a kind of superior mediator. − Recently, Shiraishi et al reported that the introduction of chloride in the reaction solution of BiOCl was beneficial for photocatalytic dinitrogen fixation through accelerating the water oxidation reaction. In the field of photocatalytic CO 2 reduction, Iguchi et al reported that the chlorides in the Ni–Al LDHs system were conducive to improving the photocatalytic activities for the conversion of CO 2 to CO and simultaneously suppressing the formation of H 2 .…”

Section: Introductionmentioning

confidence: 99%

Selective Photocatalytic Reduction of CO₂ to CH₄ Modulated by Chloride Modification on Bi₂WO₆ Nanosheets

Fan

Tan

et al. 2020

ACS Appl. Mater. Interfaces

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Solar-driven photocatalytic CO2 reduction into CH4 with H2O is considered to be a promising way to alleviate the energy crisis and greenhouse effect. However, current CO2 photoreduction technologies tend to overlook the role of photooxidation half reaction as well as the effect of the protons produced by water oxidation on CH4 generation, resulting in low CO2 conversion efficiency and poor CH4 selectivity. In the present study, a series of chloride-modified Bi2WO6 nanosheets were constructed in view of chloride-assisted photocatalytic water oxidation. The results show that the CH4 yield of the synthesized sample can be enhanced up to about 10 times compared to that with no Cl– modification. Besides, the selectivity of CH4 can be regulated by the loading amount of chloride, varying from 51.29% for Bi2WO6 to 94.98% for the maximum. The increase of product yield is attributed to chloride modification, which not only changed the morphology of the catalyst, but also modified the pathway of water oxidation. Further studies on intermediate products and the density functional theory calculation confirm that the Cl– ions on Bi2WO6 nanosheets not only promote H2O oxidation, but also lower the energy barrier for intermediate *CHO generation, thus facilitating CH4 production. The results gained herein may provide some illuminating insights into the design of a highly selective photocatalyst for efficient CO2 reduction.

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Chloride ion: A promising hole scavenger for photocatalytic hydrogen generation

Cited by 22 publications

References 44 publications

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Cathodically activated Au/TiO2 nanocomposite synthesized by a new facile solvothermal method: An efficient electrocatalyst with Pt-like activity for hydrogen generation

Selective Photocatalytic Reduction of CO₂ to CH₄ Modulated by Chloride Modification on Bi₂WO₆ Nanosheets

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Chloride ion: A promising hole scavenger for photocatalytic hydrogen generation

Cited by 22 publications

References 44 publications

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Cathodically activated Au/TiO2 nanocomposite synthesized by a new facile solvothermal method: An efficient electrocatalyst with Pt-like activity for hydrogen generation

Selective Photocatalytic Reduction of CO2 to CH4 Modulated by Chloride Modification on Bi2WO6 Nanosheets

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Selective Photocatalytic Reduction of CO₂ to CH₄ Modulated by Chloride Modification on Bi₂WO₆ Nanosheets