Engineering of anatase/rutile TiO2 heterophase junction via in-situ phase transformation for enhanced photocatalytic hydrogen evolution

Liu, Yanan; Zou, Xuhui; Li, Lifen; Shen, Zhangfeng; Cao, Yongyong; Wang, Yanqin; Cui, Lifeng; Cheng, Jun; Wang, Yangang; Li, Xi

doi:10.1016/j.jcis.2021.04.127

Cited by 42 publications

(18 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Photocatalytic water splitting for H 2 production using solar energy and semiconductor photocatalysts is considered one of the most promising technologies to solve the increasingly serious environmental and energy-related issues. − Titanium dioxide (TiO 2 ) has been extensively studied as a model photocatalyst for water splitting owing to its suitable band positions, high chemical stability, low toxicity, and abundant availability. , However, due to the easy recombination of photogenerated charge carriers, the efficiency of TiO 2 in photocatalytic H 2 production is still far from satisfactory. , Numerous strategies have, therefore, been explored to increase the separation efficiency of photoinduced electron–hole pairs within TiO 2 . − Among them, constructing heterophase junction is well accepted to be a pretty effective way since differences between the energy band structures of the components of a heterophase junction exist, which generate strong driving force for charge transfer across the well-matched interfaces. , Without the need to introduce extrinsic elements or other semiconductors, the fabrication of TiO 2 -based heterophase junction has drawn substantial interest from the scientific community. , The past years witness significant advances in the development of TiO 2 -based heterophase junctions and investigation of their photocatalytic properties. A series of TiO 2 -based heterophase junctions, such as anatase/rutile, − anatase/brookite, , TiO 2 (B)/anatase, , brookite/rutile, anatase/rutile/brookite, and anatase/rutile/TiO 2 (B), have been successfully produced. The promoted spatial separation of photogenerated electron–hole pairs and enhanced photocatalytic activity for H 2 production of these heterophase junctions have also been well illustrated.…”

Section: Introductionmentioning

confidence: 99%

Construction of TiO₂(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

et al. 2022

View full text Add to dashboard Cite

The development of facile and green solution-phase routes toward the fabrication of TiO 2 -based heterophase junctions with a delicate control of phase and structure is a challenging task. Herein, we report a simple and convenient method to controllably fabricate TiO 2 (B)/anatase heterophase junctions, which was successfully realized by utilizing the ideal great solvent of water to treat the presynthesized TiO 2 (B) nanosheet precursor at a low temperature of 80 °C. On the basis of phase structure transformation and morphology evolution data, the formation of these TiO 2 (B)/anatase heterophase junctions was reasonably explained by a novel water-induced TiO 2 (B) → anatase phase transformation mechanism. Benefiting from the desirable structural and photoelectronic advantages of more exposed active sites, enhanced light absorbance, and promoted separation of photogenerated electron−hole pairs, the thus-transformed TiO 2 (B)/anatase heterophase junctions exhibit fascinating photocatalytic performance in water splitting. Specifically, with the help of Pt as a cocatalyst and methanol as a sacrificial agent, the H 2 production rate of optimized TiO 2 (B)/anatase heterophase junction reaches 6.92 mmol• g −1 •h −1 , which is almost 7.1 and 2.1 times higher than those of the pristine TiO 2 (B) nanosheets and the final anatase nanocrystals. More interestingly, the TiO 2 (B)/anatase heterophase junction also delivers prominent activity toward pure water splitting to simultaneously produce H 2 and H 2 O 2 , with evolution rates of up to 1.10 and 0.55 mmol•g −1 •h −1 , respectively. Our work may advance the facile green solvent-mediated synthesis of metal oxide-based heterophase junctions for applications in energy-and environmental-related areas.

show abstract

Section: Introductionmentioning

confidence: 99%

Construction of TiO₂(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

et al. 2022

View full text Add to dashboard Cite

show abstract

“…[55] The band bending at the interface of anatase and rutile TiO 2 accumulated the photo-induced electrons in the rutile phase and holes in the anatase phase, leading to effective charge separation and increased photo-induced e -/h + lifetime (Figure S19b, Supporting Information). [36,56,57,59] The salophen monomer showed a PL peak at 525 nm (Figure S19a, Supporting Information). For both poly-S@anatase TiO 2 and poly-S@P25 TiO 2 , we observed slightly broad PL spectra at 532 nm maxima.…”

Section: Band Diagram Investigation and Carrier Dynamics Studymentioning

confidence: 99%

Unveiling a Three Phase Mixed Heterojunction via Phase‐Selective Anchoring of Polymer for Efficient Photocatalysis

Jadhav

Bui

Cho

et al. 2022

Advanced Energy Materials

View full text Add to dashboard Cite

because solar energy is freely available and hydrogen fuel is clean with high gravimetric energy density. For practical applications, it is very important to develop a low-cost water-splitting photocatalyst with an ≈10% solar-to-hydrogen energy conversion. [4] Nearly half of the energy in the sunlight that reaches Earth's surface comes from visible light photons (400-700 nm); therefore, it is important to develop a visible light active photocatalyst for efficient solar-to-fuel conversion. [5] Most of the research on photocatalysts has focused on wide bandgap semiconductors, such as TiO 2 , [6][7][8] SrTiO 3 , [9,10] and carbon nitride (CN). [11][12][13] Some of these photocatalysts have achieved very good operation stabilities that surpass 1000 h, along with more than 50% maximum external quantum efficiency for watersplitting reactions. [14][15][16] However, the wide and difficult-to-tune bandgaps of such photocatalysts restrict light absorption to only the ultraviolet (UV) region and thus fundamentally limit the practical applications for solar light harvesting to fuel. [16,17] Therefore, novel photocatalyst semiconductor materials with narrower bandgaps that can absorb a greater proportion of solar spectrum are needed to achieve the maximum theoretical solar energy conversion efficiency for practical applications.The ligand-to-metal charge transfer (LMCT) facilitated activation of TiO 2 has noteworthy potential for solar energy harvesting. However, the fast back electron transfer from TiO 2 to an oxidized sensitizer is a key limiting factor causing low photocatalyst efficiency. Herein, a new catalyst design to both increase LMCT efficiency and minimize the back electron transfer is presented. A phase-selective modification of mixed-phase TiO 2 (anatase: rutile interface) with poly-salophen organic polymer is developed. The salophen and salen family organic monomers are selectively bound and polymerized on the anatase phase but not the rutile phase, which results in the formation of a three-phase system. Such a three-phase system converts an unfavorable polymer TiO 2 core-shell structure to an intimately mixed blend morphology, consisting of interfaced crystalline rutile TiO 2 and an amorphous polymer-covered anatase-phase TiO 2 . The developed mixed-blend morphology poly-S@P25 can produce H 2 of 37 410 µmol h -1 g -1 of polymer, which is ≈3.4 times higher than core-shell poly-S@anatase TiO 2 . This approach overcomes the drawback of the traditional core-shell structured system for efficient electron harvesting from the LMCT process.

show abstract

“…Materials composed of a mixture of both crystalline phases but with a high anatase content can promote the activity of TiO 2 through enhanced charge carrier separation at the catalyst surface. The performance of materials with heterophase junctions (engineering of a perfect phase interface within the semiconductor) are superior to conventional heterojunction catalysts (fabrication of a heterojunction catalyst from two different semiconductors with respect to their band alignment), which facilitates electron transfer . In addition, the existence of a mixed phase can introduce a high abundance of defect sites such as oxygen vacancies, Ti interstitials, and Ti 3+ in the TiO 2 crystal lattice. , TiO 2 , with these intrinsic defects, is catalytically more active, compared to pristine TiO 2 …”

Section: Introductionmentioning

confidence: 99%

Unravelling the Impact of Ta Doping on the Electronic and Structural Properties of Titania: A Combined Theoretical and Experimental Approach

et al. 2022

View full text Add to dashboard Cite

The introduction of new energy levels in the forbidden band through the doping of metal ions is an effective strategy to improve the thermal stability of TiO 2 . In the present study, the impact of Ta doping on the anatase to rutile transition, structural characteristics, and anion and cation vacancy formation were investigated in detail using density functional theory and experimental characterization, including X-ray diffraction, Raman, Brunauer−Emmett−Teller surface area, UV−vis diffuse reflectance spectroscopy, high-resolution transmission electron spectroscopy, and X-ray photoelectron spectroscopy. The average crystallite size of TiO 2 decreases with an increase in the Ta concentration. At high temperatures, more oxygen atoms enter the crystal lattice and occupy the vacancies, leading to lattice expansion. Importantly, we find that Ta doping preserved the anatase content of TiO 2 up to annealing temperatures of 850 °C which allows anatase stability to be maintained at typical ceramic processing temperatures. The substitution of Ti 4+ by the Ta 5+ ions increased the electron concentration in the crystal lattice through formation of Ti 3+ defect states. Raman studies revealed the formation of new Ta bonds via disturbing the Ti−O−Ti bonds in the crystal lattice. It is concluded that under the oxidizing conditions the Ta 5+ ions could be enhanced on the Ta−TiO 2 surface due to slow diffusion kinetics.

show abstract

Engineering of anatase/rutile TiO2 heterophase junction via in-situ phase transformation for enhanced photocatalytic hydrogen evolution

Cited by 42 publications

References 49 publications

Construction of TiO₂(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

Construction of TiO₂(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

Unveiling a Three Phase Mixed Heterojunction via Phase‐Selective Anchoring of Polymer for Efficient Photocatalysis

Unravelling the Impact of Ta Doping on the Electronic and Structural Properties of Titania: A Combined Theoretical and Experimental Approach

Contact Info

Product

Resources

About

Engineering of anatase/rutile TiO2 heterophase junction via in-situ phase transformation for enhanced photocatalytic hydrogen evolution

Cited by 42 publications

References 49 publications

Construction of TiO2(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

Construction of TiO2(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

Unveiling a Three Phase Mixed Heterojunction via Phase‐Selective Anchoring of Polymer for Efficient Photocatalysis

Unravelling the Impact of Ta Doping on the Electronic and Structural Properties of Titania: A Combined Theoretical and Experimental Approach

Contact Info

Product

Resources

About

Construction of TiO₂(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production

Construction of TiO₂(B)/Anatase Heterophase Junctions via a Water-Induced Phase Transformation Strategy for Enhanced Photocatalytic Hydrogen Production