Electronic structures of the MoS<sub>2</sub>/TiO<sub>2</sub>(anatase) heterojunction: influence of physical and chemical modifications at the 2D- or 1D-interfaces

Favre, R.; Raybaud, Pascal; Bahers, Tangui Le

doi:10.1039/d1cp05151b

Cited by 7 publications

(3 citation statements)

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“…Since TiO 2 is an n‐type semiconductor, [ 23 ] the MoS 2 /TiO 2 heterojunction can form type‐I or type‐II bandgap alignment depending on their relative Fermi level locations. [ 24 ] Meanwhile, in the type‐I bandgap alignment, the photogenerated electrons and holes go to the same side (MoS 2 ) and quickly recombine, and thus there is no effective charge separation. The resulted propulsion should be dominated by self‐diffusiophoresis, which cannot explain the observed ionic response of the motors.…”

Section: Resultsmentioning

confidence: 99%

2D‐Material‐Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection

Huang

Guo

et al. 2022

Advanced Materials

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powered by chemical reactions encounters an arduous challenge, that is, the translocation speed is often compromised grievously in ionic suspension; [6] the alleviation of such an issue requires investigating new materials, schemes, and understanding of the complex mechanisms of locomotion. Furthermore, this far, the materials employed in chemical micro/ nanomotors that can operate continuously largely rely on noble metals such as Pt and Au combined with semiconductor oxides, for example, TiO 2 and ZnO, [1a,7] which are either expensive or are restricted in the UV region for light-powered chemical propulsion. It is highly desirable to explore new materials that can enhance the performance of chemical motors in an inexpensive, broadly applicable, and functional manner. [8] In the last decade, 2D materials, such as graphene, boron nitride, and transitionmetal-dichalcogenides have emerged as a promising class of materials owing to their 2D stacking atomic structures, high environmental stability, low cost, and the associated unique chemical and physical properties. [9] For instance, the 2D-structured molybdenum disulfide (MoS 2 ) possesses distinct semiconductor properties. The bandgap can be facilely tuned by its thickness from 1.2 eV (in bulk) to 1.8 eV (monolayer structure), accompanied by a transition from indirect to direct semiconductor bandgap structure, [10] which corresponds to an absorption edge of 1033.3 to 688.9 nm, mainly in the visible region. As a result, MoS 2 can respond to visible light with rapid optoelectric switching with a rise and decay time of 8 and 16 ms, respectively. [9a] Due to the 2D crystal structure, MoS 2 can be routinely made into van der Waals terminated thin films with lowdensity surface defects, ideal for flexible electronics. [11] Of paramount importance, when engineered with high-density defects, MoS 2 nanostructures demonstrate excellent chemical catalysis for hydrogen-evolution reduction, with a theoretical value close to that of Pt while at a much lower cost. [12] Furthermore, by leveraging the chemical properties of their defects, MoS 2 can readily react with mercury and be chemically functionalized for click-chemistry reactions. [9a] When applied in an aqueous medium, MoS 2 nanostructures are chemically stable even in an acid environment. [13] All these properties made the 2D MoS 2 a highly potential material that could make a remarkable impact on the field of micro/nanomachines, motors, and robots. For instance, MoS 2 was integrated into Pt nanotubes and demonstrated the controllable loading and release of doxorubicin. [14] 2D transition-metal-dichalcogenide materials, such as molybdenum disulfide (MoS 2 ) have received immense interest owing to their remarkable structureendowed electronic, catalytic, and mechanical properties for applications in optoelectronics, energy storage, and wearable devices. However, 2D materials have been rarely explored in the field of micro/nanomachines, motors, and robots. Here, MoS 2 with anatase TiO 2 is successfully integrated into an...

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Section: Resultsmentioning

confidence: 99%

2D‐Material‐Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection

Huang

Guo

et al. 2022

Advanced Materials

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“…[ 43 ] The heterostructure of MoS 2 /TiO 2 (101) was constructed based on the previous work as shown in Figure S8, Supporting Information. [ 44 ] In particular, 3 layers of MoS 2 were constructed on the top of TiO 2 (101) where the bottom 4 Ti layers were fixed.…”

Section: Methodsmentioning

confidence: 99%

2D/1D MoS₂/TiO₂ Heterostructure Photocatalyst with a Switchable CO₂ Reduction Product

et al. 2022

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climate change. [1] Thus, there is an acute need to develop green technologies for converting solar energy into pure chemical energy that could reduce the greenhouse effect and alleviates the global energy crunch. [2] Photocatalytic CO 2 reduction into CO or economic hydrocarbon fuel like methane (CH 4 ), as well as photoelectrochemical water splitting into a zerocarbon emission fuel (H 2 production) are promising ways to convert and store solar energy. [2c,3] Semiconductor nanoparticles have gained interest in the fields of photocatalysis, water splitting, and energy conservation and conversion. [2b,3c,4] Among them, titanium oxide has played a significant role in efficiently mitigating air and water pollution problems due to its excellent optoelectronic properties and long-term photostability. [2c,4-7] Yet, the inappropriate large energy band gap, high electron-hole recombination, and unfavorably low solar light consumption have hindered the photoconversion efficiency of the pristine TiO 2 semiconductor. [2c,4b,8] Heterostructuring TiO 2 with an appropriate semiconductor is an operative approach to overcome its drawbacks and construct an efficient photocatalyst. [2c,4a,8] MoS 2 is an appealing semiconductor for fabricating heterostructured Regulating the transfer pathway of charge carriers in heterostructure photocatalysts is of great importance for selective CO 2 photoreduction. Herein, the charge transfer pathway and in turn the redox potential succeeded to regulate in 2D MoS 2 /1D TiO 2 heterostructure by varying the light wavelength range. Several in situ measurements and experiments confirm that charge transfer follows either an S-scheme mechanism under simulated solar irradiation or a heterojunction approach under visible light illumination, elucidating the switchable property of the MoS 2 /TiO 2 heterostructure. Replacing the simulated sunlight irradiation with the visible light illumination switches the photocatalytic CO 2 reduction product from CO to CH 4.13 CO 2 isotope labeling confirms that CO 2 is the source of carbon for CH 4 and CO products. The photo electrochemical H 2 generation further supports the switching property of MoS 2 /TiO 2 . Unlike previous studies, density functional theory calculations are used to investigate the band structure of Van der Waals MoS 2 /TiO 2 S scheme after contact, allowing to propose accurate charge transfer pathways, in which the theoretical results are well matched with the experimental results. This work opens the opportunity to develop photocatalysts with switchable charge transport and tunable redox potential for selective artificial photosynthesis.

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“…26 In the case of TiO 2 supported MoS 2 , density functional theory (DFT) calculations have shown that the SL interacting with TiO 2 surfaces through van der Waals may lead to the formation of type II heterojunctions providing the potential Z-scheme. 27 In contrast, the value and indirect nature of the a-MoO 3 band gap keep almost unchanged from few layers (FLs) to a single-layer (SL). 28 Hence, 2D/2D heterojunctions involving MoS 2 and other materials have been explored 20,29 in the field of photocatalysis.…”

Section: Introductionmentioning

confidence: 99%

Tailoring the optoelectronic properties and dielectric profiles of few-layer S-doped MoO₃ and O-doped MoS₂ nanosheets: a first-principles study

Shahrokhi

Bahers

Raybaud

2022

Phys. Chem. Chem. Phys.

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Electronic structures of the MoS₂/TiO₂(anatase) heterojunction: influence of physical and chemical modifications at the 2D- or 1D-interfaces

Abstract: To tackle the challenge of the CO2 photoreduction, semiconducting layered transition metal dichalcogenides like MoS2 have attracted much attention due to their tunable 2D nano-structures. By using advanced periodic density...

Cited by 7 publications

References 53 publications

2D‐Material‐Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection

2D‐Material‐Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection

2D/1D MoS₂/TiO₂ Heterostructure Photocatalyst with a Switchable CO₂ Reduction Product

Tailoring the optoelectronic properties and dielectric profiles of few-layer S-doped MoO₃ and O-doped MoS₂ nanosheets: a first-principles study

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Electronic structures of the MoS2/TiO2(anatase) heterojunction: influence of physical and chemical modifications at the 2D- or 1D-interfaces

Abstract: To tackle the challenge of the CO2 photoreduction, semiconducting layered transition metal dichalcogenides like MoS2 have attracted much attention due to their tunable 2D nano-structures. By using advanced periodic density...

Cited by 7 publications

References 53 publications

2D‐Material‐Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection

2D‐Material‐Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection

2D/1D MoS2/TiO2 Heterostructure Photocatalyst with a Switchable CO2 Reduction Product

Tailoring the optoelectronic properties and dielectric profiles of few-layer S-doped MoO3 and O-doped MoS2 nanosheets: a first-principles study

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Electronic structures of the MoS₂/TiO₂(anatase) heterojunction: influence of physical and chemical modifications at the 2D- or 1D-interfaces

2D/1D MoS₂/TiO₂ Heterostructure Photocatalyst with a Switchable CO₂ Reduction Product

Tailoring the optoelectronic properties and dielectric profiles of few-layer S-doped MoO₃ and O-doped MoS₂ nanosheets: a first-principles study