Biomembrane-Compatible Sol–Gel-Derived Photocatalytic Titanium Dioxide

Johnson, Kaitlin; Gakhar, Sukriti; Deng, Yue; Fong, Keiko; Risbud, Subhash H.; Longo, Marjorie L.

doi:10.1021/acsami.7b12673

Cited by 16 publications

(13 citation statements)

References 40 publications

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“…Given the vulnerability of Cu 2 O, the electrolyte solution has to be near neutral. On the other side, Ti 3+ is unstable as well, which hydrolyzes when pH > 4 and can be easily oxidized into hydrated TiO 2 ( Johnson et al, 2017 ). Hence, all reported cases were performed under very low pH with relatively stable substrates.…”

Section: Resultsmentioning

confidence: 99%

Room Temperature Electrodeposition of Ready-to-Use TiOx for Uniform p-n Heterojunction Over Nanoarchitecture

et al. 2022

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The photocathodes are essential in photoelectrochemical systems for harvesting solar energy as green fuels. However, the light-absorbing p-type semiconductor in them usually suffers from carrier recombination issues. An effective strategy to address it is fabricating the p-n heterojunction to create an interfacial electric field. However, plenty of deposition process of the n-type layer for this purpose requires either sophisticated instruments or subsequent treatments, which may damage the vulnerable p-type structure. Herein, we report a mild approach for a ready-to-use n-type layer with full functionality. Structural analyses proved the successful coating of a uniform titania layer (up to 40 nm) over Cu2O without damaging its structure. Owing to the high Ti3+ content, the layer possesses excellent charge transport ability and requires no additional annealing. The heterojunction effectively facilitates the carrier separation and positively shifts the photocurrent onset potential for 0.2 V. The Mott–Schottky plot and the impedance study reveal an enhanced carrier collection with reduced charge transfer resistances. Such a nano-heterojunction can be further loaded with the hydrogen evolution catalyst, which almost doubles the photocurrent with an extended lifetime than that of the pristine Cu2O nanoarray. This approach puts forward a potentially scalable and efficient choice for fabricating photoelectrochemical devices.

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Section: Resultsmentioning

confidence: 99%

Room Temperature Electrodeposition of Ready-to-Use TiOx for Uniform p-n Heterojunction Over Nanoarchitecture

et al. 2022

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“…Previously, we characterized the UV−vis absorbance spectra of the retinal chromophore of encapsulated BR in titania gels which confirmed the ability of the protein to make conformational changes associated with the proton pumping photocycle under confinement. 17 Those titania gels were synthesized without the addition of ethanol because we found this formulation to result in high amounts of stable confined BR without significant levels of denaturation, in contrast to gels synthesized with 2.6 and 5.2 M added ethanol which denatured the BR. Here, titania gels with encapsulated BR were characterized using fluorescence spectroscopy.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…29 Alcohols are known to disrupt the hydrogen bonding responsible for stabilization of the tertiary structure within protein and the increase in hydrophobicity of longer hydrocarbon chains allows for higher insertion efficiency into hydrophobic regions of the protein and any associated membrane. 29 In our previous work, 17 titania gels were fabricated using 0, 2.6, and 5.2 M added ethanol. The molarity of methanol added during synthesis was matched to the molarity of alcohol used in that work.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Photocatalytic activity in the gels was previously compared with the behavior of P25 nanopowder under the same conditions. 17 A SpectraMax M2 UV/vis spectrophotometer (Molecular Devices, LLC., Sunnyvale, CA) was used to determine the absorbance of all samples before and after UV irradiation. Degradation of the methylene blue within samples was calculated by monitoring the peak height at 665 nm as this is directly proportional to the concentration of methylene blue through the Beer−Lambert law.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…16 In our previous work, amorphous titania gel monoliths were shown to achieve photocatalytic breakdown of a model organic dye, methylene blue, at a degree and rate comparable to that of commercial crystalline titania nanopowder. 17 Additionally, BR was encapsulated within titania and shown to retain the ability to make reversible conformational changes associated with the photocycle. 17 This indicates BR is likely to retain the functionality necessary to perform proton pumping within the pores of the gel.…”

Section: ■ Introductionmentioning

confidence: 99%

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Development and Characterization of Titanium Dioxide Gel with Encapsulated Bacteriorhodopsin for Hydrogen Production

et al. 2018

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We study bacteriorhodopsin (BR) in its native purple membrane encapsulated within amorphous titanium dioxide, or titania, gels and in the presence of titania sol particles to explore this system for hydrogen production. Förster resonance energy transfer between BR and titanium dioxide sol particles was used to conclude that there is nanometer-scale proximity of bacteriorhodopsin to the titanium dioxide. The detection of BR-titania sol aggregates by fluorescence anisotropy and particle sizing indicated the affinity amorphous titania has for BR without the use of additional cross-linkers. UV-vis spectroscopy of BR-titania gels shows that methanol addition did not denature BR at a 25 mM concentration presence as a sacrificial electron donor. Additionally, confinement of BR in the gels significantly limited protein denaturation at higher concentration of added methanol or ethanol. Subsequently, titania gels fabricated through the sol-gel process using a titanium ethoxide precursor, water, and the addition of 25 mM methanol were used to encapsulate BR and a platinum reduction catalyst for the production of hydrogen gas under white light irradiation. The inclusion of 5 μM bacteriorhodopsin resulted in a hydrogen production rate of about 3.8 μmol hydrogen mL h, an increase of 52% compared to gels containing no protein. Electron transfer and proton pumping by BR in close proximity to the titania gel surface are feasible explanations for the enhanced production of hydrogen without the need to cross-link BR to the titania gel. This work sets the stage for further developments of amorphous, rather than crystalline, titania-encapsulated bacteriorhodopsin for solar-driven hydrogen production through water splitting.

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