Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure

Wu, Min‐Hsien; Chen, Ching‐Hsiang; Huang, Wei-Kang; Hsiao, Kai‐Chi; Lin, Ting‐Han; Chan, Shun‐Hsiang; Wu, Peng; Lu, Chun‐Fu; Chang, Yu Sheng; Lin, Tz-Feng; Hsu, Kai‐Hsiang; Hsu, Jen‐Fu; Lee, Kun‐Mu; Shyue, Jing‐Jong; Kordás, Krisztián; Su, Wei‐Fang

doi:10.1038/srep40896

Cited by 43 publications

(8 citation statements)

References 64 publications

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“…The potential of pristine rutile TiO 2 , R-700, and R-800 all shifted further to the negative direction, indicating that the electrons can be generated under UV light and lead to a further upward shift of Fermi energy from E f to E fn . 23,34,45 Accordingly, the changes of surface potential (ΔSP) under UV illumination among pristine rutile TiO 2 , R-700, and R800 can be regarded as an indicator of photocatalytic activity, consistent with the H 2 generation rate. The largest change on R-700 indicates that the R-700 structure is in favor of accumulation of photogenerated electrons on the surface.…”

Section: ■ Discussionmentioning

confidence: 99%

Origin of Photocatalytic Activity in Ti⁴⁺/Ti³⁺ Core–Shell Titanium Oxide Nanocrystals

Lin¹,

et al. 2019

J. Phys. Chem. C

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Colored titanium dioxide (TiO 2 ) nanocrystals have been studied intensively in recent years due to their substantial solar-driven photocatalytic activities. Because of the scarcity of information correlated among atomic structure, electronic structure, and photocatalytic property from isolated nanoparticles, the origin of photocatalytic activity of colored TiO 2 from microscopic and electronic level remains intensely debated. Here we demonstrated the origin of photocatalytic activity in Ti 4+ /Ti 3+ core−shell TiO 2 nanocrystals mainly by a combination of high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), and photo-Kelvin probe force microscopy (KPFM). The thickness of the Ti 3+ shell layer increases with the annealing temperature, meanwhile the O/Ti atomic ratio of the outermost layer decrease. The differences in interplanar spacing between the surface and the subsurface generate strain effect, which increase carrier mobility and ultimately improve catalytic performance. Quantum size effect and specific surface area also have a big impact on catalytic performance. A prerequisite is to keep a good balance between the Ti 4+ /Ti 3+ core−shell structure and the particle size to optimize its photocatalytic properties. By employing Au as a reference, we were able to estimate the Fermi levels of TiO 2 before and after illumination. The amplitude of the Fermi level upshift unambiguously relates with the photocatalytic activity. The largest Fermi level upshift under illumination means generating the most efficient photoinduced carries to perform a highly catalytic reaction, carried out by optimizing the electronic structure with appropriate oxygen vacancies. But too many oxygen vacancies increase the recombination center and reduce the concentration of photoinduced electrons, which can also be observed from the photo-KPFM result.

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Section: ■ Discussionmentioning

confidence: 99%

Origin of Photocatalytic Activity in Ti⁴⁺/Ti³⁺ Core–Shell Titanium Oxide Nanocrystals

Lin¹,

et al. 2019

J. Phys. Chem. C

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“…The PL lifetime spectra of ZnO and N–ZnO4 NRAs are shown in Figure S2. The decay plot was fitted by the biexponential kinetics function 26 where A 1 and A 2 are the corresponding amplitudes, τ 1 and τ 2 are the fast and slow decay times, and τ avg is the average lifetime.…”

Section: Resultsmentioning

confidence: 99%

Nitrogen-Implanted ZnO Nanorod Arrays for Visible Light Photocatalytic Degradation of a Pharmaceutical Drug Acetaminophen

et al. 2019

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The present study focuses on the effects of nitrogen (N) ion implantation in vertically aligned ZnO nanorod arrays (NRAs) and the photocatalytic degradation of acetaminophen. The X-ray diffraction of these NRAs exhibit a wurtzite structure with a predominant (002) diffraction peak that shifts slightly after N-ion implantation. The field emission scanning electron microscopic images of as-prepared NRAs show a length of ∼4 μm and diameter of ∼150 nm. UV–visible spectroscopy reveals that the band gap of pristine ZnO NRAs decreases from 3.2 to 2.18 eV after N-ion implantation. Under visible irradiation, the N-ion-implanted ZnO catalyst exhibits significant enhancement of the photocatalytic degradation of acetaminophen from 60.0 to 98.46% for 120 min.

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“…Therefore, it is expected that the photoactivity of Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 mpc and Co 3 (PO 4 ) 2 -Co 2 P 2 O 7 mpc particles are good; in particular, Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 mpc particles with a high interfacial transition and defects have high photocatalytic activity. A recent study described the hetero-phase junction phenomenon in association with crystal defects [47]. That is because positive or negative ion defects are generated in crystals, they act as electron or hole capture sites, slowing the recombination rate and increasing the activity of the photocatalyst [48].…”

Section: Resultsmentioning

confidence: 99%

Hydrogen Production Improvement on Water Decomposition Through Internal Interfacial Charge Transfer in M3(PO4)2-M2P2O7 Mixed-Phase Catalyst (M = Co, Ni, and Cu)

et al. 2019

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In this study, three types of Nasicon-type materials, Co 3 (PO 4 ) 2 -CO 2 P 2 O 7 , Ni 3 (PO 4 ) 2 -Ni 2 P 2 O 7 , and Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 , were synthesized as mixed-phase catalysts (MPCs) for evaluating their potential as new photocatalytic candidates (called Co 3 (PO 4 ) 2 -CO 2 P 2 O 7 mpc, Ni 3 (PO 4 ) 2 -Ni 2 P 2 O 7 mpc, and Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 mpc herein). Based on various physical properties, it was confirmed that there are two phases, M 3 (PO 4 ) 2 and M 2 P 2 O 7 , in which a similar phase equilibrium energy coexists. These colored powders showed UV and visible light responses suitable to our aim of developing 365-nm light-response photocatalysts for overall water-splitting. The photocatalytic performance of Ni 2 (PO 4 ) 3 -Ni 2 P 2 O 7 MPC showed negligible or no activity toward H 2 evolution. However, Co 2 (PO 4 ) 3 -Co 2 P 2 O 7 MPC and Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 MPC were determined as interesting materials because of their ability to absorb visible light within a suitable band. Moreover, an internal interface charge transfer was suggested to occur that would lower the recombination rate of electrons and holes. For Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 MPC, the charge separation between the electron and hole was advantageously achieved, a water-splitting reaction was promoted, and hydrogen generation was considerably increased. The performance of a catalyst depended on the nature of the active metal added. In addition, the performance of the catalyst was improved when electrons migrated between the inter-phases despite the lack of a heterojunction with other crystals.

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Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure

Cited by 43 publications

References 64 publications

Origin of Photocatalytic Activity in Ti⁴⁺/Ti³⁺ Core–Shell Titanium Oxide Nanocrystals

Origin of Photocatalytic Activity in Ti⁴⁺/Ti³⁺ Core–Shell Titanium Oxide Nanocrystals

Nitrogen-Implanted ZnO Nanorod Arrays for Visible Light Photocatalytic Degradation of a Pharmaceutical Drug Acetaminophen

Hydrogen Production Improvement on Water Decomposition Through Internal Interfacial Charge Transfer in M3(PO4)2-M2P2O7 Mixed-Phase Catalyst (M = Co, Ni, and Cu)

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Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure

Cited by 43 publications

References 64 publications

Origin of Photocatalytic Activity in Ti4+/Ti3+ Core–Shell Titanium Oxide Nanocrystals

Origin of Photocatalytic Activity in Ti4+/Ti3+ Core–Shell Titanium Oxide Nanocrystals

Nitrogen-Implanted ZnO Nanorod Arrays for Visible Light Photocatalytic Degradation of a Pharmaceutical Drug Acetaminophen

Hydrogen Production Improvement on Water Decomposition Through Internal Interfacial Charge Transfer in M3(PO4)2-M2P2O7 Mixed-Phase Catalyst (M = Co, Ni, and Cu)

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Origin of Photocatalytic Activity in Ti⁴⁺/Ti³⁺ Core–Shell Titanium Oxide Nanocrystals

Origin of Photocatalytic Activity in Ti⁴⁺/Ti³⁺ Core–Shell Titanium Oxide Nanocrystals