- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Controlling dye coverage instead of addition of organic acid to reduce dye aggregation in dye-sensitized solar cells
摘要： The photo-generated electron injection yield of dye-sensitized solar cells (DSSCs) based on donor-acceptor conjugated dyes is lowered by the aggregation of surface adsorbed organic dyes that pose a low-photoenergy conversion efficiency. Coadsorbates used to prevent the aggregation cause to decompose or detach the dye molecules anchored on the TiO2 surface. In this study, the effect of coadsorption of organic acid and organic dyes on photovoltaic performances was systematically scrutinized by means of adsorption isotherms and photovoltaic measurements. Our laboratory synthesized {0 1 0}-faceted TiO2 (PA TiO2) and P25 TiO2 were used as meso-porous nanocrystals, D149 organic dye was used as a sensitizer and cheno-deoxycholic acid, CDA, was used as a coadsorbate. The coadsorption of CDA reduces the adsorption parameters, maximum adsorption density (Qm) and adsorption constant (Kad), and the reduction depended on the type of TiO2. The photovoltaic performance indicates that the D149 dye has the best dye coverage at around 70% for the effective photovoltaic energy conversion. The coadsorption of CDA increased the photovoltaic performances of DSSCs based on P25 TiO2 but, CDA decreased the photovoltaic performances of DSSCs based on PA TiO2 due to the reduction of the dye coverage below 70%. The results suggest that the coadsorption of organic acids is not necessary if the particular TiO2 can maintain its coverage at the best coverage. Thus, the requirement of coadsorbates to reduce the dye aggregation depends on the type of TiO2 used in DSSCs.
关键词： Coverage,Adsorption isotherms,Coadsoptions,Aggregations,Photovoltaic performances,Dye-sensitized solar cells
更新于2025-09-23 15:21:01
-
Chemisorption and sensitivity at semiconductor sensors revisited
摘要： In this work we derived the adsorption isotherms for non-dissociative and dissociative chemisorption of oxygen on a semiconductor surface. We extended the Wolkenstein theory for dissociative chemisorption and re-examined the basis that led to currently accepted formalisms in the literature. In particular, we correctly incorporated dissociative chemisorption as a second-order reaction. We determined band bendings and adsorbate coverages for different gas pressure and doping for a typical metal-oxide used in gas sensing. Finally, consequences for the sensor conductivity and sensitivity are discussed.
关键词： Chemisorption,Conductivity,Adsorption isotherms,Semiconductor gas sensors
更新于2025-09-19 17:15:36
-
Controlled Fabrication of K2Ti8O17 Nanowires for Highly Efficient and Ultrafast Adsorption towards Methylene Blue
摘要： Advanced adsorbents need high adsorption rate and superior adsorption capability to clean up the organic methylene blue (MB) from wastewater. We prepared K2Ti8O17 nanowires grown along [0 1 0] direction with a one-step hydrothermal method. The K2Ti8O17 nanowires with tens of nanometers in diameter and tens of micrometers in length were achieved with smooth surfaces and twisted wire-like morphology. The K2Ti8O17 nanowires exhibit high uptake capacity of ～208.8 mg·g?1 in the MB removal under equilibrium pH = 7. The adsorption equilibriums of MB onto K2Ti8O17 adsorbent is achieved with 97% removal rate MB within only ~21 min, which is the shortest adsorption time among the recent reported inorganic adsorbents towards MB. The adsorption process has a good agreement with the well-known pseudo-second-order kinetic model (k2 = 0.2) and the Langmuir isotherm model. The FTIR measurements suggest that the adsorption can be assigned to the hydrogen bonding and electrostatic attraction between MB and K2Ti8O17. This ultrafast removal ability owns to the larger (0 2 0) interplanar spacing and zigzag surface structure of the nanowires, which provide abundant active adsorption sites. Thermodynamic parameters reflect the spontaneous, exothermic and feasible uptake of MB. Besides, K2Ti8O17 nanowires enjoy high adsorptive ability for chromium (VI) ions and photocatalytic removal towards NO. This work highlights the great significance of K2Ti8O17 nanowires as a low cast promising material used for adsorptive elimanation of organic contaminations in fast water purification on a large scale.
关键词： Hydrothermal synthesis,Tunnel-layered structure,Adsorption capability,K2Ti8O17 nanowires,Thermodynamics,Kinetics,Isotherms
更新于2025-09-16 10:30:52
-
Combined statistical physics models and DFT theory to study the adsorption process of paprika dye On TiO2 for dye sensitized solar cells
摘要： This study reported the combination of advanced statistical physics modeling and density functional theory (DFT) investigation for the interpretation of the adsorption of Paprika dye on TiO2 surface for dye sensitized solar cells. By using a statistical physics modeling method, an adequate monolayer model with four energies was successfully used to interpret the adsorption process at a macroscopic level. The DFT simulation has been used to study the interaction of the Paprika dye on TiO2 surface to understand some of the atomistic details that are crucial to the dye/semiconductor interaction. We pay particular attention to the adsorption modes, geometries and energies between the paprika dye and TiO2. The DFT simulation determined different binding modes which participated in the adsorption of Paprika dye on TiO2 surface: monodentate coordination via hydrogen atom bond, monodentate coordination via oxygen atom bond and bidentate coordination via two oxygen atoms bond. In particular, calculations showed that the interaction between the paprika dye and TiO2 is strengthened with the bidentate coordination mode via the two hydroxyl and ether functionalities groups involved in the adsorption process.
关键词： Statistical physics modeling,Dye sensitized solar cells,Paprika oleoresin dye,Adsorption isotherms,DFT simulation
更新于2025-09-11 14:15:04