Sunlight-charged heterojunction TiO2 and WO3 particle-embedded inorganic membranes for night-time environmental applications

Dong Suk Han, Rand Elshorafa, Sun Hee Yoon, Seonghun Kim, Hyunwoong Park, Ahmed Abdel-Wahab

Research output: Contribution to journalArticle

Abstract

A metal oxide-heterojunction photocatalyst is developed to harvest sunlight, store the energy in electrons, and apply the stored energy in water treatment. Light-absorbing nanoparticular and nanotubular TiO2 are hybridized with electron-storing WO3 at different weight ratios of TiO2 to WO3 (e.g., TW25 represents a composite of 25 wt% TiO2 and 75 wt% WO3). The ability of the TW composite to utilize the stored electrons is examined for the reduction of hexavalent chromium (Cr(vi)). In the photoelectrochemical (PEC) tests, irradiation using simulated sunlight (AM 1.5, 100 mW cm-2) leads to a rapid shift in the open-circuit potential (OCP) of the TW electrodes to the negative potential region (photocharging process). The termination of irradiation causes a gradual shift of the OCP to the positive potential region over 20 h (discharging process). Spiked Cr(vi) added to the solution with pre-photocharged TW electrodes is efficiently removed; the kinetics of this process depends on the TW composition (25, 50, or 75 wt%), TiO2 morphology (particular or tubular), initial Cr(vi) concentration (0.125 or 0.25 ppm), and whether the conditions are aerated or non-aerated. Based on this knowledge, TW composite-embedded inorganic membranes are synthesized and charged using sunlight. For Cr(vi) removal, single-pass and continuous circulation filtration systems are employed. The fraction of Cr(vi) removed from the circulation system is ∼30% in 4 h, which is 1.5 times that removed using the single-pass filtration system (∼20%). An X-ray photoelectron spectroscopy analysis of the TW membranes used for Cr(vi) removal reveals that Cr is not sorbed in the membrane. The W(vi) in WO3 is partially reduced to W(6-x)+ upon photocharging and is oxidized during the reduction of Cr(vi), leading to the co-existence of W6+ and W(6-x)+.

Original languageEnglish
Pages (from-to)491-498
Number of pages8
JournalPhotochemical and Photobiological Sciences
Volume17
Issue number4
DOIs
Publication statusPublished - 1 Jan 2018

Fingerprint

sunlight
night
Heterojunctions
heterojunctions
membranes
Membranes
Electrons
Composite materials
Irradiation
composite materials
Electrodes
Networks (circuits)
Photocatalysts
Water treatment
Oxides
irradiation
electrons
water treatment
electrodes
shift

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Sunlight-charged heterojunction TiO2 and WO3 particle-embedded inorganic membranes for night-time environmental applications. / Han, Dong Suk; Elshorafa, Rand; Yoon, Sun Hee; Kim, Seonghun; Park, Hyunwoong; Abdel-Wahab, Ahmed.

In: Photochemical and Photobiological Sciences, Vol. 17, No. 4, 01.01.2018, p. 491-498.

Research output: Contribution to journalArticle

@article{ed99b5bc4d024d16ad056854868d1ef0,
title = "Sunlight-charged heterojunction TiO2 and WO3 particle-embedded inorganic membranes for night-time environmental applications",
abstract = "A metal oxide-heterojunction photocatalyst is developed to harvest sunlight, store the energy in electrons, and apply the stored energy in water treatment. Light-absorbing nanoparticular and nanotubular TiO2 are hybridized with electron-storing WO3 at different weight ratios of TiO2 to WO3 (e.g., TW25 represents a composite of 25 wt{\%} TiO2 and 75 wt{\%} WO3). The ability of the TW composite to utilize the stored electrons is examined for the reduction of hexavalent chromium (Cr(vi)). In the photoelectrochemical (PEC) tests, irradiation using simulated sunlight (AM 1.5, 100 mW cm-2) leads to a rapid shift in the open-circuit potential (OCP) of the TW electrodes to the negative potential region (photocharging process). The termination of irradiation causes a gradual shift of the OCP to the positive potential region over 20 h (discharging process). Spiked Cr(vi) added to the solution with pre-photocharged TW electrodes is efficiently removed; the kinetics of this process depends on the TW composition (25, 50, or 75 wt{\%}), TiO2 morphology (particular or tubular), initial Cr(vi) concentration (0.125 or 0.25 ppm), and whether the conditions are aerated or non-aerated. Based on this knowledge, TW composite-embedded inorganic membranes are synthesized and charged using sunlight. For Cr(vi) removal, single-pass and continuous circulation filtration systems are employed. The fraction of Cr(vi) removed from the circulation system is ∼30{\%} in 4 h, which is 1.5 times that removed using the single-pass filtration system (∼20{\%}). An X-ray photoelectron spectroscopy analysis of the TW membranes used for Cr(vi) removal reveals that Cr is not sorbed in the membrane. The W(vi) in WO3 is partially reduced to W(6-x)+ upon photocharging and is oxidized during the reduction of Cr(vi), leading to the co-existence of W6+ and W(6-x)+.",
author = "Han, {Dong Suk} and Rand Elshorafa and Yoon, {Sun Hee} and Seonghun Kim and Hyunwoong Park and Ahmed Abdel-Wahab",
year = "2018",
month = "1",
day = "1",
doi = "10.1039/c7pp00451f",
language = "English",
volume = "17",
pages = "491--498",
journal = "Photochemical and Photobiological Sciences",
issn = "1474-905X",
publisher = "Royal Society of Chemistry",
number = "4",

}

TY - JOUR

T1 - Sunlight-charged heterojunction TiO2 and WO3 particle-embedded inorganic membranes for night-time environmental applications

AU - Han, Dong Suk

AU - Elshorafa, Rand

AU - Yoon, Sun Hee

AU - Kim, Seonghun

AU - Park, Hyunwoong

AU - Abdel-Wahab, Ahmed

PY - 2018/1/1

Y1 - 2018/1/1

N2 - A metal oxide-heterojunction photocatalyst is developed to harvest sunlight, store the energy in electrons, and apply the stored energy in water treatment. Light-absorbing nanoparticular and nanotubular TiO2 are hybridized with electron-storing WO3 at different weight ratios of TiO2 to WO3 (e.g., TW25 represents a composite of 25 wt% TiO2 and 75 wt% WO3). The ability of the TW composite to utilize the stored electrons is examined for the reduction of hexavalent chromium (Cr(vi)). In the photoelectrochemical (PEC) tests, irradiation using simulated sunlight (AM 1.5, 100 mW cm-2) leads to a rapid shift in the open-circuit potential (OCP) of the TW electrodes to the negative potential region (photocharging process). The termination of irradiation causes a gradual shift of the OCP to the positive potential region over 20 h (discharging process). Spiked Cr(vi) added to the solution with pre-photocharged TW electrodes is efficiently removed; the kinetics of this process depends on the TW composition (25, 50, or 75 wt%), TiO2 morphology (particular or tubular), initial Cr(vi) concentration (0.125 or 0.25 ppm), and whether the conditions are aerated or non-aerated. Based on this knowledge, TW composite-embedded inorganic membranes are synthesized and charged using sunlight. For Cr(vi) removal, single-pass and continuous circulation filtration systems are employed. The fraction of Cr(vi) removed from the circulation system is ∼30% in 4 h, which is 1.5 times that removed using the single-pass filtration system (∼20%). An X-ray photoelectron spectroscopy analysis of the TW membranes used for Cr(vi) removal reveals that Cr is not sorbed in the membrane. The W(vi) in WO3 is partially reduced to W(6-x)+ upon photocharging and is oxidized during the reduction of Cr(vi), leading to the co-existence of W6+ and W(6-x)+.

AB - A metal oxide-heterojunction photocatalyst is developed to harvest sunlight, store the energy in electrons, and apply the stored energy in water treatment. Light-absorbing nanoparticular and nanotubular TiO2 are hybridized with electron-storing WO3 at different weight ratios of TiO2 to WO3 (e.g., TW25 represents a composite of 25 wt% TiO2 and 75 wt% WO3). The ability of the TW composite to utilize the stored electrons is examined for the reduction of hexavalent chromium (Cr(vi)). In the photoelectrochemical (PEC) tests, irradiation using simulated sunlight (AM 1.5, 100 mW cm-2) leads to a rapid shift in the open-circuit potential (OCP) of the TW electrodes to the negative potential region (photocharging process). The termination of irradiation causes a gradual shift of the OCP to the positive potential region over 20 h (discharging process). Spiked Cr(vi) added to the solution with pre-photocharged TW electrodes is efficiently removed; the kinetics of this process depends on the TW composition (25, 50, or 75 wt%), TiO2 morphology (particular or tubular), initial Cr(vi) concentration (0.125 or 0.25 ppm), and whether the conditions are aerated or non-aerated. Based on this knowledge, TW composite-embedded inorganic membranes are synthesized and charged using sunlight. For Cr(vi) removal, single-pass and continuous circulation filtration systems are employed. The fraction of Cr(vi) removed from the circulation system is ∼30% in 4 h, which is 1.5 times that removed using the single-pass filtration system (∼20%). An X-ray photoelectron spectroscopy analysis of the TW membranes used for Cr(vi) removal reveals that Cr is not sorbed in the membrane. The W(vi) in WO3 is partially reduced to W(6-x)+ upon photocharging and is oxidized during the reduction of Cr(vi), leading to the co-existence of W6+ and W(6-x)+.

UR - http://www.scopus.com/inward/record.url?scp=85045726022&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85045726022&partnerID=8YFLogxK

U2 - 10.1039/c7pp00451f

DO - 10.1039/c7pp00451f

M3 - Article

VL - 17

SP - 491

EP - 498

JO - Photochemical and Photobiological Sciences

JF - Photochemical and Photobiological Sciences

SN - 1474-905X

IS - 4

ER -