Bismuth-based material has been broadly studied due to their potential applications in various areas, especially used as promising photocatalysts for the removal of persistent organic pollutants (POPs) and several approaches have been adopted to tailor their features. Herein, the bismuth-based photocatalysts (BiOCl, BiPO4, BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques (XRD, SEM, EDS elemental mapping, Raman and UV–vis DRS) were employed to analyze their morphology, crystal structure, and purity of the prepared photocatalysts. These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2 (P25) for the degradation of model pollutant perfluorooctanoic acid (PFOA) under 254 nm UV light. It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order: bismuth-based catalysts > TiO2 (P25) > without catalyst. Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition. Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment. 相似文献
Anatase TiO2 photocatalysts supported with the ordered mesoporous carbon, CMK-3, were synthesized by the incorporation of TiO2 into CMK-3 followed by heating at 700 °C. The structural properties of the TiO2 on CMK-3 were investigated by X-ray diffraction, nitrogen physisorption and electron microscopy techniques. In particular, TiO2 was observed both inside and the external surface of CMK-3. The photocatalytic activity of TiO2 on CMK-3 under UV-light exhibited higher efficiency in removing the Rhodamine 6G dye solution than the commercial photocatalyst P25 and TiO2 on activated carbon. It was attributed to the synergistic effect of large surface area adsorption provided by mesoporous CMK-3 and the distinctive location of TiO2 on the external surface of CMK-3. 相似文献
Limited visible-light absorption and high recombination rate of photogenerated charges are two main drawbacks in g-C3N4-based photocatalysts. To solve these problems, g-C3N4/nitrogen-doped graphene quantum dots (NGQDs)/TiO2 ternary heterojunctions were facilely prepared via a one-step calcining method. The morphology, structure, optical and electrochemical properties of g-C3N4/NGQDs/TiO2 were characterized and explored. The optimal g-C3N4/NGQDs/TiO2 composite exhibits enhanced photocatalytic degradation performance of ciprofloxacin (CIP) compared with the as-prepared g-C3N4, TiO2(P25) and g-C3N4/TiO2 heterojunction under visible light irradiation. The apparent rate constant of the composite is around 6.43, 4.03 and 2.30 times higher than those of g-C3N4, TiO2 and g-C3N4/TiO2, respectively. The enhanced photocatalytic efficiency should be mainly attributed to the improvement of light absorption and charge separation and transfer efficiency, originating from the narrow band gap and high charge carrier mobility. The active species trapping experiments results showed that the h+ and ·O2- were the main active species in the degradation process. A possible photocatalytic reaction mechanism of the g-C3N4/NGQDs/TiO2 composite for the enhanced degradation of CIP under visible light irradiation was also proposed. 相似文献
TiO2 nanoparticles and H2Ti2O5·H2O, Na2Ti2O4(OH)2 nanotubes were synthesized by solvothermal method and their applications in the degradation of active Brilliant-blue (KN-R) solution were investigated. The experimental results revealed that the synthesized TiO2 nanoparticles had a good crystallinity and a narrow size distribution (about 4–5 nm); the obtained H2Ti2O5·H2O, Na2Ti2O4(OH)2 were tubelike products with an average diameter of 20–30 and 200–300 nm length. The three catalysts we synthesized had some hydroxyl groups and the maximum absorption boundaries of the samples were all red-shifted, which indicated the samples had a promising prospect in photocatalysis.
The results of the photocatalytic experiments indicated that the photocatalytic activity of the samples was: TiO2 > H2Ti2O5·H2O > Na2Ti2O4(OH)2, which was in good accordance with the fact of FTIR and UV–vis absorption spectra. The formation mechanism of these nanostructures was also discussed. 相似文献
In this work, Bi_2Ti_2O_7/TiO_2 composites were synthesized and studied as potential visible-light-activated photocatalysts in the reduction of aqueous Cr(VI). Bi_2Ti_2O_7/TiO_2 composites with tunable compositions were synthesized via a solvothermal-calcination two-step method, simply by changing the molar ratios of Bi(NO_3)_3·5H_2O to tetrabutyl titanate in the reactants. The compositions, structures and optical properties of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites were characterized by X-ray diffraction, field emission scanning electron microscopy and UV–vis diffuse reflectance spectra. The photocatalytic activity of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites was tested in the reduction of aqueous Cr(VI)under visible-light(λ420 nm) irradiation, and compared with that of TiO_2 nanoparticles. It was observed that the as-synthesized Bi_2Ti_2O_7/TiO_2 composites exhibited much higher photocatalytic activity than TiO_2 nanoparticles, and the most efficient composite(300 mg) can achieve the complete reduction of Cr(VI) in 300 mL of 50 mg/L K_2Cr_2O_7 aqueous solution under visible-light(λ420 nm)irradiation in 90 min. 相似文献
Biphasic defective TiO2-x/reduced graphene oxide(RGO) nanocomposites were synthesized by simple hydrothermal reactions. Compared with TiO2-x and commercial P25, TiO2-x/RGO shows much better photocatalytic activity and excellent stability in pollutants degradation, which could be ascribed to Ti3+ centers complexed with RGO and the synergetic effect between the two phases. The study reveals a new route for the synthesis of mixed-phase defective TiO2-x/carbon material nanocomposites for photocatalytic applications. 相似文献
The threat and global concern of energy crises have significantly increased over the last two decades. Because solar light and water are abundant on earth, photocatalytic hydrogen evolution through water splitting has been considered as a promising route to produce green energy. Therefore, semiconductor photocatalysts play a key role in transforming sunlight and water to hydrogen energy. To date, various photocatalysts have been studied. Among them, TiO2 has been extensively investigated because of its non-toxicity, high chemical stability, controllable morphology, and high photocatalytic activity. In particular, 1D TiO2 nanofibers (NFs) have attracted increasing attention as effective photocatalysts because of their unique 1D electron transfer pathway, high adsorption capacity, and high photoinduced electron–hole pair transfer capability. However, TiO2 NFs are considered as an inefficient photocatalyst for the hydrogen evolution reaction (HER) because of their disadvantages such as a large band gap (~3.2 eV) and fast recombination of photoinduced electron–hole pairs. Therefore, the development of a high-performance TiO2 NF photocatalyst is required for efficient solar light conversion. In recent years, several strategies have been explored to improve the photocatalytic activity of TiO2 NFs, including coupling with narrow-bandgap semiconductors (such as ZnIn2S4). Recently, microwave (MW)-assisted synthesis has been considered as an important strategy for the preparation of photocatalyst semiconductors because of its low cost, environment-friendliness, simplicity, and high reaction rate. Herein, to overcome the above-mentioned limiting properties of TiO2 NFs, we report a 2D/1D ZnIn2S4/TiO2 S-scheme heterojunction synthesized through a microwave (MW)-assisted process. Herein, the 2D/1D ZnIn2S4/TiO2 S-scheme heterojunction was constructed rapidly by using in situ 2D ZnIn2S4nanosheets decorated on 1D TiO2 NFs. The loading of ZnIn2S4 nanoplates on the TiO2 NFs could be easily controlled by adjusting the molar ratios of ZnIn2S4 precursors to TiO2 NFs. The photocatalytic activity of the as-prepared samples for water splitting under simulated solar light irradiation was assessed. The experimental results showed that the photocatalytic performance of the ZnIn2S4/TiO2 composites was significantly improved, and the obtained ZnIn2S4/TiO2 composites showed increased optical absorption. Under optimal conditions, the highest HER rate of the ZT-0.5 (molar ratio of ZnIn2S4/TiO2= 0.5) sample was 8774 μmol·g-1·h-1, which is considerably higher than those of pure TiO2 NFs (3312 μmol·g-1·h-1) and ZnIn2S4nanoplates (3114 μmol·g-1·h-1) by factors of 2.7 and 2.8, respectively. Based on the experimental data and Mott-Schottky analysis, a possible mechanism for the formation of the S-scheme heterojunction between ZnIn2S4 and TiO2 was proposed to interpret the enhanced HER activity of the ZnIn2S4/TiO2heterojunctionphotocatalysts.相似文献
The performance of dye-sensitized solar cells(DSSCs) consisting of anatase TiO_2 nanoparticles that were synthesized via a hydrothermal method was studied.The synthesized TiO_2 nanoparticles were characterized by X-ray diffraction(XRD),nitrogen sorption analysis,scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM),and UV-vis spectroscopy.Then the J-Vcurve,electrochemical impedance spectroscopy(EIS),and open-circuit voltage decay(OCVD) measurement were applied to evaluate the photovoltaic performance of DSSCs.Compared with the commercial TiO_2nanoparticles(P25),the synthesized-TiO_2 nanoparticles showed better performance.By adding diethylene glycol(DEG) before the hydrothermal process,the synthesized TiO_2 nanoparticles(hereafter referred to as TiO_2-DEG particles) shows narrower size distribution,larger specific surface area,higher crystallinity,and less surface defects than TiO_2(DEG free) particles.The analysis of photovoltaic properties of DSSCs based on TiO_2-DEG particles showed that the recombination of electron-hole pairs was decreased and the trapping of carries in grain boundaries restrained.It was believed that the photoelectrode fabricated with the as-prepared TiO_2 nanoparticles improved the loading amount of dye sensitizers(N719).and enhanced the photocurrent of the DSSCs.As a result,the TiO_2-DEG particle based cells achieved a photo-to-electricity conversion efficiency(η) of 7.90%,which is higher than 7.53%for the cell based on TiO2(DEG free) and 6.59%for the one fabricated with P25. 相似文献
The degradation of 2-chlorophenol (2-CP) was investigated by a combination of TiO2-based photocatalysis and adsorption. Three combined systems were compared: (i) TiO2 was intercalated into the interlamellar space of a hydrophilic montmorillonite by means of a heterocoagulation process (TiO2 pillared montmorillonite, TPM); (ii) TiO2 was hydrothermally crystallized on hexadecylpyridinium chloride-treated montmorillonite (HDPM-T); (iii) hexadecylpyridinium chloride-treated montmorillonite (HDPM) was used as adsorbent and Degussa P25 TiO2 as photocatalyst (HDPM/TiO2).
The process of mineralization of the organic substrate was characterized by measuring the total organic carbon (TOC) and total inorganic chloride contents, while the degradation of 2-CP and the formation of intermediates were followed by HPLC. The adsorbent-photocatalyst systems were characterized by X-ray diffraction measurements. In all the investigated systems, the degradation of 2-CP was accompanied by a continuous decrease in TOC content. The most advantageous situation was found with HDPM/TiO2, for which the highest rate of oxidation of 2-CP was observed. In this case the photocatalytically recovered adsorbent may be re-used without further regeneration. A significantly lower 2-CP degradation rate was observed when TiO2 was fixed on layer silicates. When TPM was applied, only a rather low decrease in TOC content was observed during 10 h of irradiation, i.e. only slight mineralization of the organic pollutant occurred, which is probably due to the low crystallinity and small size of the TiO2 particles. In the case of HDPM-T, the observed quite high reduction in TOC content shows that the hydrothermally processed TiO2 sample may compete with the Degussa P25, but the degradation of the organic pollutant is accompanied by a continuous destruction of the adsorbent. 相似文献