Polypyrrole-decorated Ag-TiO2 nanofibers exhibiting enhanced photocatalytic activity under visible-light illumination

Synthesis of g-C3N4/Bi2O3/TiO2 composite nanotubes: enhanced activity under visible light irradiation and improved photoelectrochemical activity

g-C₃N₄ and Bi₂O₃ were successfully incorporated into TiO₂ nanotubes. The photocurrent generated by g-C₃N₄/Bi₂O₃/TiO₂-NTs was about 15 times higher.g-C₃N₄/Bi₂O₃/TiO₂-NT has a higher PEC response for the degradation of organic pollutants.

Simple synthesis and photoelectrochemical characterizations of polythiophene/Pd/TiO2 composite microspheres

We report here a simple, effective, and low cost method to synthesize polythiophene/Pd/TiO2 (PTh/Pd/TiO2) ternary composite microspheres and apply such a composite to photoelectrochemical (PEC) sensing. TiO2 spherical aggregates of 200 nm diameter, consisting of nanoscale building blocks of TiO2, have been prepared by hydrolysis of tetrabutyl titanate in a water-in-oil emulsion system (Vwater/Vacetone=1/100). Pd species and PTh layer were decorated onto TiO2 microspherical substrates by reduction of Pd salts and polymerization of thiophene, respectively. The high surface area, effective charge transfer, and enhanced light absorption of the ternary composite could improve PEC performance under simulated sunlight. The sensitivity, selectivity, and stability of PEC sensor for detecting l-cysteine were much higher than those of the traditional electrochemical sensor. The detection limit of l-cysteine was 9.24 μM in the linear range of 0.31-5.30 mM. Moreover, the results also indicated a good anti-interference and acceptable accuracy in practical application, providing a rapid and sensitive detection method.

Quick and facile preparation of visible light-driven TiO2 photocatalyst with high absorption and photocatalytic activity

Self-doping TiO₂ has recently attracted considerable attention for its high photocatalytic activity under visible-light irradiation. However, the literature reported synthetic methods until now were very time-consuming. In this study, we establish a quick and facile method for obtaining self-doping TiO₂ with the use of directly treated commercial P25 at a desired temperature for only 5 min through spark plasma sintering technology. With the using of this method, the modified P25 samples exhibit significantly high photoelectric and photocatalytic performance. Furthermore, the sample prepared at 600°C exhibits the optimum catalytic activity. The photodegradation and H₂ evolution rates of this samples are significantly higher than those of unmodified P25 sample under visible-light irradiation. The physical origin of the visible-light absorption for the modified P25 samples is investigated in detail according to their structural, optical, and electronic properties. This work will provide a quick and facile method for the large-scale synthesis of visible-light driven photocatalyst for practical applications.

Conjugated polymer/nanocrystal nanocomposites for renewable energy applications in photovoltaics and photocatalysis

Conjugated polymer/nanocrystal composites have attracted much attention for use in renewable energy applications because of their versatile and synergistic optical and electronic properties. Upon absorbing photons, charge separation occurs in the nanocrystals, generating electrons and holes for photocurrent flow or reduction/oxidation (redox) reactions under proper conditions. Incorporating these nanocrystals into conjugated polymers can complement the visible light absorption range of the polymers for photovoltaics applications or allow the polymers to sensitize or immobilize the nanocrystals for photocatalysis. Here, the current developments of conjugated polymer/nanocrystal nanocomposites for bulk heterojunction-type photovoltaics incorporating Cd- and Pb-based nanocrystals or quantum dots are reviewed. The effects of manipulating the organic ligands and the concentration of the nanocrystal precursor, critical factors that affect the shape and aggregation of the nanocrystals, are also discussed. In the conclusion, the mechanisms through which conjugated polymers can sensitize semiconductor nanocrystals (TiO2 , ZnO) to ensure efficient charge separation, as well as how they can support immobilized nanocrystals for use in photocatalysis, are addressed.

Optimization and application of TiO₂/Ti-Pt photo fuel cell (PFC) to effectively generate electricity and degrade organic pollutants simultaneously

A TiO2/Ti-Pt photo fuel cell (PFC) was established to generate electricity and degrade organic pollutants simultaneously. The electricity generation was optimized through investigation the influences of photoanode calcination temperature and dissolve oxygen on the resistances existing in PFC. TiO2 light quantum yield was also improved in PFC which resulted in a higher PC degradation efficiency. Two kinds of real textile wastewaters were also employed in this PFC system, 62.4% and 50.0% Coulombic efficiency were obtained for 8 h treatment. These refractory wastewaters with high salinity may become good fuels in PFC because a) TiO2 has no selectivity and can degrade nearly any organic substance, b) no more electrolyte is needed due to the high salinity, c) the energy in wastes can be recovered to generate electricity. The electricity generated by the PFC was further applied on a TiO2/Ti rotating disk photoelectrocatalytic reactor. A bias voltage between 0.6 and 0.75 V could be applied and the PC degradation efficiency was significantly improved. This result was similar with that obtained by a 0.7 V DC power.

Enhanced thermal stability under DC electrical conductivity retention and visible light activity of Ag/TiO₂@polyaniline nanocomposite film

The development of organic-inorganic photoactive materials has resulted in significant advancements in heterogeneous visible light photocatalysis. This paper reports the synthesis of visible light-active Ag/TiO2@Pani nanocomposite film via a simple biogenic-chemical route. Electrically conducting Ag/TiO2@Pani nanocomposites were prepared by incorporating Ag/TiO2 in N-methyl-2-pyrrolidone solution of polyaniline (Pani), followed by the preparation of Ag/TiO2@Pani nanocomposite film using solution casting technique. The synthesized Ag/TiO2@Pani nanocomposite was confirmed by UV-visible spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The Ag/TiO2@Pani nanocomposite film showed superior activity towards the photodegradation of methylene blue under visible light compared to Pani film, even after repeated use. Studies on the thermoelectrical behavior by DC electrical conductivity retention under cyclic aging techniques showed that the Ag/TiO2@Pani nanocomposite film possessed a high combination of electrical conductivity and thermal stability. Because of its better thermoelectric performance and photodegradation properties, such materials might be a suitable advancement in the field of smart materials in near future.

Manipulation on ZnO heterostructures: from binary ZnO–Ag to ternary ZnO–Ag–polypyrrole

A ternary composite ZnO–Ag–polypyrrole was synthesized through a fast reaction between zinc acetate and hexamethylenetetramine followed by an in situ surface polymerization process. The sample exhibited a superior catalytic performance in the degradation of methylene blue under both UV irradiation and visible light.

Bi2Sn2O7–TiO2 nanocomposites for enhancing visible light photocatalytic activity

Bi₂Sn₂O₇–TiO₂ nanocomposites with different ratios of Bi₂Sn₂O₇ (BSO) and TiO₂ were prepared by combining a facile co-precipitation method with the aid of a template.