- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Co-sensitization of porphyrin and metal-free dye for panchromatic dye-sensitized solar cells
摘要： Porphyrin dyes are outstanding photosensitizers. However, one of the limitations of using porphyrin dyes for dye-sensitized solar cells (DSSC) is their weak absorption in the 500–600 nm region. Co-sensitization approach with two complementary dyes is an approach to solve this problem. So, to enhance the DSSC performance by improving harvesting solar light, we have studied porphyrin dye (LD12) and an organic dye (D149) as the co-sensitizer. This co-sensitized LD12 + D149 device with complementary in their spectral responses shows the power conversion efficiency about 6.8%, which is higher compared with the individual LD12 and D149 solar cells. The obtained photon-to-current conversion efficiency (IPCE) by using this co-sensitized solar cell demonstrates a strong and broad spectral response. This improvement is due to increment of the dyes loading amounts, the fine-matched molecular structures and absorptions of both dyes as the co-sensitization system.
关键词： Dye-sensitized solar cells,Organic dye,Porphyrin,Co-sensitization
更新于2025-09-11 14:15:04
-
Sensitizing effects of BiVO4 and visible light induced production of highly reductive electrons in the TiO2/BiVO4 heterojunction
摘要： BiVO4 is an e?cient and stable visible active photoanode material. However, due to its unfavorable conduction band position which falls below the H2 reduction potential, it fails to carry out the complete water splitting reaction. On the other hand, larger band gap TiO2 is able to photocatalytically split water, thanks to its negative conduction band energy. Aiming at verifying the possibility of sensitizing TiO2 with BiVO4 and employing the so obtained composite material in photocatalytic water splitting under visible light, we prepared and photoelectrochemically characterized TiO2/BiVO4 heterojunction electrodes. The photocatalytic reduction of methyl viologen, an electron acceptor probe with a reduction potential close to that of protons, was used to evaluate the reducing ability of the photoactive materials under visible light. An apparently counterintuitive electron transfer from photoexcited BiVO4 to the TiO2 conduction band occurs in the TiO2/BiVO4 heterojunction, resulting in TiO2 sensitization and production of highly reductive electrons, which appears to be favored by the band alignment occurring at the heterojunction.
关键词： Methyl viologen reduction,Photo(electro)catalysis,TiO2,BiVO4,Heterojunction,Visible light sensitization
更新于2025-09-10 09:29:36
-
Role of phosphate in ruthenium-complex-sensitized TiO2 system for hydrogen production: mechanism and kinetics
摘要： Most Ru(II) complex-sensitized TiO2 systems for hydrogen (H2) production suffer from instability of the photosensitized system because the anchoring groups of Ru(II) dyes, which are required for their adsorption on TiO2, are intrinsically vulnerable to chemical and photochemical cleavage. In this study, a new method that enables the use of a Ru(II) dye without any anchoring groups (Ru(bpy)3 2+) was developed and investigated. The stable photocatalytic efficiency in repeated H2 production cycles under visible-light irradiation indicates that the Ru(II) dye without anchoring groups is highly stable during dye-sensitized H2 production. The dye-sensitized H2 production in the Ru(bpy)3 2+-sensitized TiO2 system comprising Ru(bpy)3 2+ as a photosensitizer, platinized TiO2 (Pt-TiO2) as a cocatalyst-electron mediator, and ethylenediaminetetraacetic acid as an electron donor was negligible. However, the addition of phosphate (PO4 3–) to the Ru(bpy)3 2+-sensitized TiO2 system enabled the production of H2 via dye sensitization in the absence of any anchoring groups on the dye. The adsorption of PO4 3– changed the surface charge of Pt-TiO2 from positive to negative under acidic conditions, thereby inducing adsorption of cationic Ru(bpy)3 2+ on the surface of Pt-TiO2 and facilitating electron transfer from excited Ru(bpy)3 2+ to the conduction band of TiO2. The PO4 3– adsorption-induced change in the surface charge and the subsequent adsorption of Ru(bpy)3 2+ on the surface of PO4 3–-adsorbed Pt-TiO2 were confirmed by zeta potential measurements and Fourier transform infrared spectroscopy, respectively. In contrast with H2 production, the presence of PO4 3– had little effect on the kinetics of anionic chromate (CrO4 2–) reduction in the Ru(bpy)3 2+-sensitized TiO2 system. This result indicates that electron transfer from Pt to the electron acceptor on PO4 3–-adsorbed Pt-TiO2 is highly dependent on the charge character of the electron acceptor (i.e., electron transfer to the cationic electron acceptor is more favored). The negative charge on the surface of Pt-TiO2 induced by the adsorption of PO4 3– attracts the positively charged protons to the surface, which kinetically enhanced electron transfer from Pt to the protons. The (photo)electrochemical data demonstrate that PO4 3– adsorbed on Pt-TiO2 facilitates the interfacial electron transfer processes by enhancing the adsorption of Ru(bpy)3 2+ and attracting protons to the surface. The positive effect of PO4 3– on H2 production increased with increasing PO4 3– concentration and decreasing pH, where the conditions are more favorable for PO4 3– and proton adsorption on the surface of Pt-TiO2. Among the five anions evaluated in this study (PO4 3–, AsO4 3–, F–, NO3 –, and SO4 2–), PO4 3– was most efficient and facilitated stable H2 production.
关键词： Phosphate,Dye sensitization,Hydrogen production,Photocatalysis,Ruthenium-complex
更新于2025-09-10 09:29:36
-
Investigation of mid-IR luminescence properties in Dy3+/Tm3+-codoped LaF3 single crystals
摘要： The spectroscopic characteristics of a series of Dy3+/Tm3+-codoped LaF3 single crystals have been studied for mid-IR emissions through Dy3+:6H13/2 → 6H15/2 transition. Optimal mid-IR emission was achieved in 3 at% Tm3+ and 2 at% Dy3+ co-doped LaF3 sample under the excitation of 790 nm. Its emission cross section was calculated to be 2.56×10-21 cm2 at the peak wavelength (2840 nm) with a FWHM of 270 nm, and the fluorescence lifetime was 3.694 ms. The fact of intense 2.84 μm emission was achieved by 790 nm pumping proves the effective energy transfer from Tm3+ to Dy3+ ions. The possible energy transfer routes were analyzed in detail, and the microscopic transfer constants were also estimated based on the phonon-assisted energy transfer theory. As a result, Dy3+/Tm3+-codoped LaF3 single crystal can be a potential medium for mid-IR lasers.
关键词： microscopic transfer constant,Dy3+/Tm3+:LaF3,sensitization mechanism,mid-IR luminescence
更新于2025-09-09 09:28:46
-
Enhanced Visible Light Sensitization of N-doped TiO2 Nanotubes Containing Ti-Oxynitride Species Fabricated via Electrochemical Anodization of Titanium Nitride
摘要： The concentration and chemical state of nitrogen represent critical factors to control the band-gap narrowing and the enhancement of visible light harvesting in nitrogen-doped titanium dioxide. In this study, photocatalytic TiO2-N nanoporous structures were fabricated by the electrochemical anodization of titanium nitride sputtered films. Doping was straightforwardly obtained by oxidizing as-sputtered titanium nitride films containing N-metal bonds varying from 7.3 to 18.5 % in the Ti matrix. Severe morphological variations into the as-anodized substrates were registered at different nitrogen concentration and studied by Small-Angle X-ray Scattering. Titanium nitride films with minimum N content of 6.2 at% N led to a quasi-nanotubular geometry, whilst an increase in N concentration up to 23.8 at% determined an inhomogeneous, polydispersed distribution of nanotube apertures. The chemical state of nitrogen in the TiO2 matrix was investigated by X-ray Photoelectron Spectroscopy depth profile analysis and correlated to the photocatalytic performance. The presence of Ti-N and β-Ti substitutional bonds, as well as Ti-oxynitride species was revealed by the analysis of N 1s X-ray Photoelectron Spectroscopy High Resolution spectra. The minimum N content of 4.1 at% in the TiO2-N corresponded to the lowest Ti-oxynitride ratio of 13.5 %. The relative variation of N-metal bonds was correlated to the visible light sensitization and the highest Ti-N/Ti oxynitride ratio of 3.3 was attributed to the lowest band-gap of 2.7 eV and associated to a threefold increase in the degradation of organic dye. Further increase of N doping led to a dramatic drop of Ti-N/Ti oxynitride ratio, from 3.3 to 0.4, which resulted in a loss photocatalytic activity. The impact of the chemical state of nitrogen towards efficient doping of TiO2 nanotubes is demonstrated with a direct correlation to the N loading and a strategy to optimise these factors based on a simple, rapid synthesis from titanium nitride.
关键词： visible light sensitization,photocatalytic performance,titanium nitride,nitrogen-doped titanium dioxide,electrochemical anodization
更新于2025-09-04 15:30:14
-
High Visible Response of Vertical TiO2 Nanoclusters-CdSe Linked by Cysteine
摘要： Vertically oriented single-crystal TiO2 nanoclusters in tetramethylammonium hydroxide solution were synthesized hydrothermally directly on Ti substrate. N-Type semiconducting CdSe nanoparticles were then introduced deep coating TiO2 nanocrystalss via a two-step procedure using cystein as a surface coupling agent, followed by a subsequent electrodeposition process from selenosulfite to form orderly interconnecting heterojunctions. A key result achievement is that although the TiO2 nanocrystalss are less than 1 μm long, under the help of the bifunctional 2-amino-3-sulfhydrylpropanoic acid molecule linking the acceptor and donor materials, the virtue of strong visible absorption of single crystal TiO2 nanoclusters were fully developed in addition of ultraviolet, so that the heterojunction electrode exhibits excellent photoresponse in photoelectrochemical cells to visible lights, whose contribution is rather significant compared with that of ultraviolet lights. Vertical nanoclusters have advantages of leading electrons directly into the metal Ti substrate while maintaining the large surface area towards the electrolyte. These highly ordered nanohybrids are expected to have potential applications in photochemical solar cells with high efficiency.
关键词： TiO2 nanocluster,Visible lights,Sensitization,CdSe,Vertically oriented
更新于2025-09-04 15:30:14
-
Donor-π-acceptor dye-sensitized photoelectrochemical and photocatalytic hydrogen evolution by using Cu2WS4 co-catalyst
摘要： Photoelectrochemical and photocatalytic hydrogen evolution reaction (HER) have been investigated by using metal free donor-acceptor (D-A) and donor-p-acceptor (D-p-A) dyes, which are abbreviated as MC-32 and MC-048, respectively, sensitized TiO2 as a photocatalyst with or without Cu2WS4 co-catalyst. This co-catalyst is synthesized by a low-cost and simple hot injection method, under visible light illumination. The photoactivities of these dyes have been clarified according to their structural, optical and electrochemical properties. Photocatalytic activities have been slightly increased when added the Cu2WS4 co-catalyst (dye/TiO2/Cu2WS4). This catalytic activity is also compared to that of noble metal Pt (dye/TiO2/Pt). It has been found that 121 mmolg-1h-1, 179 mmolg-1h-1, 348 mmolg-1h-1, 212 mmolg-1h-1, 422 mmolg-1h-1 and 1139 mmolg-1h-1 hydrogen have been evolved by using MC-32/TiO2, MC-32/TiO2/Cu2WS4, MC-32/TiO2/Pt, MC-048/TiO2, MC-048/TiO2/Cu2WS4 and MC-048/TiO2/Pt, respectively.
关键词： Dye sensitization,Donor-p-acceptor dyes,Hydrogen evolution
更新于2025-09-04 15:30:14
-
A TiO2/g-C3N4/CdS Nanocomposite-Based Photoelectrochemical Biosensor for Ultrasensitive Evaluation of T4 Polynucleotide Kinase Activity
摘要： Herein, an efficient photoelectrochemical (PEC) platform was constructed by a co-sensitization strategy with a cascade energy level arrangement for the ultrasensitive evaluation of T4 polynucleotide kinase (T4 PNK). Based on CdSe quantum dots (QDs) with an extremely narrow bandgap, this co-sensitization strategy offered a highly efficient sensitizer with a matching band-edge level of a ternary TiO2/g-C3N4/CdS nanocomposite. In this protocol, the ternary nanocomposite was first prepared to serve as the matrix to construct the PEC sensing platform. On the other hand, a well-designed hairpin DNA1 probe with 5’-hydroxyl termini was specifically phosphorylated by T4 PNK which would be selectively cleaved with lambda exonuclease (λ-Exo) outputting 3’-thiol end ssDNA2. After tagged with CdSe QDs, ssDNA2 was captured by the complementary capture DNA3 on the electrode surface. As a result, CdSe QDs were in close contact with the ternary nanocomposite matrix, leading to an enhanced photocurrent response. Therefore, this proposed PEC platform displayed an analytical performance with a wide linear range from 0.0001 to 0.02 U mL-1 and a low detection limit down to 6.9 × 10-5 U mL-1. Moreover, this ternary nanocomposite-based platform exhibited excellent selectivity, good reproducibility, and remarkable storage stability, which shows the great potential for the T4 PNK detection and inhibitor screening.
关键词： CdSe quantum dots,T4 polynucleotide kinase,ternary nanocomposite,co-sensitization strategy,photoelectrochemical biosensor
更新于2025-09-04 15:30:14