A visible-light-driven composite photocatalyst of TiO₂ nanotube arrays and graphene quantum dots

• Donald K. L. Chan,
• Po Ling Cheung and
• Jimmy C. Yu

Beilstein J. Nanotechnol. 2014, 5, 689–695, doi:10.3762/bjnano.5.81

• light irradiation. Keywords: anodic oxidation; graphene quantum dots; photocatalyst; photodegradation; TiO2 nanotube arrays; Introduction Semiconductor-mediated photocatalysis is a promising technique for the conversion of solar energy as well as degradation of organic pollutants in air and water [1

• photoelectrochemical water splitting [38]. In the present work, a composite photocatalyst of graphene quantum dots and TiO2 nanotube arrays (GQDs/TNAs) was fabricated by the coupling reaction between carboxyl-containing GQDs and amine-functionalized TNAs (Scheme 1). The experimental data revealed that sensitization of

• interfacial electron transfer from GQDs to TNAs is possible. Meanwhile, such a directional charge transfer promotes charge separation and reduces the probability of charge recombination, then further increases the activity of the photocatalyst. Conclusion In summary, a visible-light-driven photocatalyst was

Effects of the preparation method on the structure and the visible-light photocatalytic activity of Ag₂CrO₄

• Difa Xu,
• Shaowen Cao,
• Jinfeng Zhang,
• Bei Cheng and
• Jiaguo Yu

Beilstein J. Nanotechnol. 2014, 5, 658–666, doi:10.3762/bjnano.5.77

• potentially serve as a visible-light-driven photocatalyst. Photocatalytic activity We have measured the zeta potential of Ag2CrO4 as −15.8 mV at pH 6.8, suggesting that it is electronegative in neutral solutions. Since MB is a cationic dye, it can be easily adsorbed on the surface of Ag2CrO4 through

• electrostatic interaction. Therefore, the photocatalytic activity of the as-prepared Ag2CrO4 samples is evaluated through MB degradation under visible-light irradiation. Without any photocatalyst, no obvious MB degradation is observed under visible-light irradiation. For comparison, P25 (commercial TiO2

Enhanced photocatalytic activity of Ag–ZnO hybrid plasmonic nanostructures prepared by a facile wet chemical method

• Sini Kuriakose,
• Vandana Choudhary,
• Biswarup Satpati and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2014, 5, 639–650, doi:10.3762/bjnano.5.75

• summarized as follows [29][30] and are schematically illustrated in Figure 8. Yin et al. [41] prepared nanocomposites with Ag nanoparticle decorated ZnO nanorods with a core–shell structure by seed-mediated method. They have shown that Ag–ZnO is a better photocatalyst than ZnO because, firstly, the

• of repetitive tests of the photocatalytic activity of AZ510 sample for four runs. It can be clearly seen that the efficiency of the photocatalyst remains high even after four runs. The effects of citrate concentration and Ag loading on the photocatalytic efficiency can be summarized as follows. It

• dispersed in 5 mL deionized water. Aqueous MB solution was added to the photocatalyst mixture and thoroughly mixed. The reaction suspensions containing 10 μM MB and different (ZnO, Ag–ZnO) photocatalysts were irradiated with sun light for different times (10, 20, 40 min) with intermittent shaking for

High activity of Ag-doped Cd_0.1Zn_0.9S photocatalyst prepared by the hydrothermal method for hydrogen production under visible-light irradiation

• Leny Yuliati,
• Melody Kimi and
• Mustaffa Shamsuddin

Beilstein J. Nanotechnol. 2014, 5, 587–595, doi:10.3762/bjnano.5.69

• Cd0.1Zn0.9S photocatalyst. Keywords: Ag doping; Cd0.1Zn0.9S; hydrogen production; hydrothermal; visible light; Introduction The development of clean and renewable hydrogen energy through a sustainable production process is still a big issue to be addressed. Solar energy is a very attractive option as it is

• band energy required for hydrogen production. However, in order to utilize solar energy in the future, a further red shift to a range of even longer wavelengths is still highly desired. The modification of Cd1−xZnxS photocatalyst with metal ions, such as Cu [9][10][11][12][13], Ni [14][15], Sn [16

• ], and Sr [17] has been a good attempt to increase the visible-light absorption of the Cd1−xZnxS photocatalyst. The use of Ag species as a good dopant for various types of photocatalysts has been also reported [18][19][20], including its use to modify Cd1−xZnxS [21][22][23]. Cd1−xZnxS modified by Ag2S

Artificial sunlight and ultraviolet light induced photo-epoxidation of propylene over V-Ti/MCM-41 photocatalyst

• Van-Huy Nguyen,
• Shawn D. Lin,
• Jeffrey Chi-Sheng Wu and
• Hsunling Bai

Beilstein J. Nanotechnol. 2014, 5, 566–576, doi:10.3762/bjnano.5.67

• photocatalyst by using artificial sunlight (Xe lamp with/without an Air Mass 1.5 Global Filter at 1.6/18.5 mW·cm−2) and ultraviolet light (Mercury Arc lamp with different filters in the range of 0.1–0.8 mW·cm−2). This is the first report of using artificial sunlight to drive the photo-epoxidation of propylene

• . Over V-Ti/MCM-41 photocatalyst, the propylene oxide (PO) formation rate is 193.0 and 112.1 µmol·gcat−1·h−1 with a PO selectivity of 35.0 and 53.7% under UV light and artificial sunlight, respectively. A normalized light utilization (NLU) index is defined and found to correlate well with the rate of

• tested in this study. Keywords: artificial sunlight; light irradiation effects; photo-epoxidation; ultraviolet (UV) light; V-Ti/MCM-41 photocatalyst; Introduction It is agreed that light, especially its wavelength spectrum and intensity, is a crucial factor for efficient photocatalysis. A

Applicability and costs of nanofiltration in combination with photocatalysis for the treatment of dye house effluents

• Wolfgang M. Samhaber and
• Minh Tan Nguyen

Beilstein J. Nanotechnol. 2014, 5, 476–484, doi:10.3762/bjnano.5.55

• ) and patent blue (C27H31N2NaO6S2), by using TiO2 Degussa P25 as the photocatalyst in a lab-scale combined system with NF membranes NTR 7410 (Nitto Denko, Tokio) and have observed that it was possible to successfully treat concentrated solutions (500 mg/L) of both dyes by means of a continuous process

• with a suspended photocatalyst. Damodar et al. [17] have studied the coupling of a MF membrane separation with a photocatalytic laboratory slurry reactor for an advanced treatment of dye effluent and achieved high removal rates (82–100% colour removal, 45–93% TOC removal, and 50–85% COD removal) at

• . Irradiation can take place in the flat sheet membrane cell or in a separated recirculation loop. Different configurations were applied for both fixed-bed photoreactors and slurry batch photoreactors. The authors indicated that an advantage of the system with the suspended photocatalyst over the fixed one is

Dye-sensitized Pt@TiO₂ core–shell nanostructures for the efficient photocatalytic generation of hydrogen

• Jun Fang,
• Lisha Yin,
• Shaowen Cao,
• Yusen Liao and
• Can Xue

Beilstein J. Nanotechnol. 2014, 5, 360–364, doi:10.3762/bjnano.5.41

• particle bridge. Keywords: charge transfer; dye-sensitization; photocatalysis; photocatalyst; solar fuels; water splitting; Introduction Since Honda and Fujishima reported the effective hydrogen evolution from water splitting by a TiO2 and Pt electrode in a photoelectrochemical cell in the early 1970s [1

• Pt@TiO2 photocatalyst was dispersed into 10 mL of an aqueous solution containing triethanolamine (TEOA, 15 wt %) as electron donor and erythrosin B (0.2 wt %) as the photo-sensitizing dye. The suspension was sealed in a quartz vessel and purged with Argon for 30 min to remove the residual oxygen

Study of mesoporous CdS-quantum-dot-sensitized TiO₂ films by using X-ray photoelectron spectroscopy and AFM

• Mohamed N. Ghazzal,
• Robert Wojcieszak,
• Gijo Raj and
• Eric M. Gaigneaux

Beilstein J. Nanotechnol. 2014, 5, 68–76, doi:10.3762/bjnano.5.6

• . Keywords: AFM; CdS; heterojunction; particle size; quantum dots; TiO2; XPS; Introduction To sensitize the photocatalyst TiO2 with cadmium sulfide quantum dots (QDs-CdS) is a well-established concept that is of great relevance in different applications. The most popular of these applications are

• sensitize TiO2. The suitable positions of the potential energies allow for an easy transfer of the exciton between the semiconductors. Not only does that help to optimize the charge separation by reducing the recombination of charges, it also allows for an extension of the photoresponse of the photocatalyst

Preparation of NiS/ZnIn₂S₄ as a superior photocatalyst for hydrogen evolution under visible light irradiation

• Liang Wei,
• Yongjuan Chen,
• Jialin Zhao and
• Zhaohui Li

Beilstein J. Nanotechnol. 2013, 4, 949–955, doi:10.3762/bjnano.4.107

• nanocomposite and is compared with that of pure ZnIn2S4 and NiS. Although NiS is a good electrocatalyst for hydrogen evolution [36], no hydrogen was evolved when NiS alone was used as the photocatalyst. Pure ZnIn2S4 only had a very low activity with the hydrogen evolution at a rate of 14.1 μmol/h. However, the

• with a heavy loading of NiS is likely due to the shading effect of NiS, which can block the absorption of the incident light by ZnIn2S4. Therefore, an appropriate loading amount of NiS is crucial to achieve the optimized photocatalytic activity of the ZnIn2S4 photocatalyst. NiS/ZnIn2S4 nanocomposites

• show high stability during the photocatalytic hydrogen evolution reaction. A prolonged photocatalytic reaction for 15 h over 0.5 wt % NiS/ZnIn2S4 revealed that no obvious loss of the activity during the whole reaction period (Figure 7). Besides this, the unchanged XRD pattern of the photocatalyst after

Structural, optical and photocatalytic properties of flower-like ZnO nanostructures prepared by a facile wet chemical method

• Sini Kuriakose,
• Neha Bhardwaj,
• Jaspal Singh,
• Biswarup Satpati and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2013, 4, 763–770, doi:10.3762/bjnano.4.87

• these toxic chemicals. Photocatalytic degradation, in which the organic pollutants are degraded through photocatalytic oxidation and reduction reactions in the presence of a photocatalyst, is one of the most promising and clean processes used for water purification. Nanostructured semiconductor

• Figures 4a–c show the UV–vis absorption spectra of an aqueous solution of 22.4 μM MB with either photocatalyst S1, S2 or S3 after irradiation with sunlight for different durations of time. The characteristic absorption peak of MB at 664 nm is monitored as a function of the sunlight exposure time. It can

• S2 we could achieve about 95% degradation of MB for the same exposure time. Almost complete (99.6%) photodegradation of MB could be achieved with S2 as photocatalyst after 60 min of exposure to sunlight, while samples S1 and S3 could degrade only 97.8% and 68.2% respectively after the same exposure

Modulation of defect-mediated energy transfer from ZnO nanoparticles for the photocatalytic degradation of bilirubin

• Tanujjal Bora,
• Karthik K. Lakshman,
• Soumik Sarkar,
• Abhinandan Makhal,
• Samim Sardar,
• Samir K. Pal and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2013, 4, 714–725, doi:10.3762/bjnano.4.81

• (Figure 1b). Following the optical characterization of the ZnO nanoparticle samples, we have explored the effect of the concentration of the surface defects in the ZnO nanoparticles on the photocatalytic degradation of BR, when using the nanoparticles as a photocatalyst medium. The photocatalytic

• temperature and stored in a refrigerator for further use. Photocatalyst preparation For the annealing of the ZnO nanoparticles, six glass substrates (1.5 cm × 1.5 cm) were placed on a hot plate (60 °C) and 100 μL of the as-prepared ZnO nanoparticle colloidal solution was dropped on each glass substrate. The

Nanostructure-directed chemical sensing: The IHSAB principle and the dynamics of acid/base-interface interaction

• James L. Gole and
• William Laminack

Beilstein J. Nanotechnol. 2013, 4, 20–31, doi:10.3762/bjnano.4.3

• transformation from acidic to basic sites. These studies also define a broadened interaction matrix as it extends from physisorption (sensing) applications to chemisorption and microreactor design. Recently, we have produced visible-light-absorbing TiO2−xNx photocatalyst nanoparticles in seconds at room

Paper modified with ZnO nanorods – antimicrobial studies

• Mayuree Jaisai,
• Sunandan Baruah and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2012, 3, 684–691, doi:10.3762/bjnano.3.78

• strong oxidizing agent [17]. The reactions initiated by photogenerated electrons, leading to the formation of hydroxyl radicals and hydrogen peroxide, are summarized as follows [19]: where MO stands for metal-oxide photocatalyst, such as TiO2, ZnO, etc., and the reaction products and intermediates are

Mesoporous MgTa₂O₆ thin films with enhanced photocatalytic activity: On the interplay between crystallinity and mesostructure

• Jin-Ming Wu,
• Igor Djerdj,
• Till von Graberg and
• Bernd M. Smarsly

Beilstein J. Nanotechnol. 2012, 3, 123–133, doi:10.3762/bjnano.3.13

• photocatalyst access to the target molecules and also possess a high specific surface area. Unfortunately, because of the high crystallization temperature and low decomposition temperature of most commercially available templates, the fabrication of ordered mesoporous MgTa2O6 thin films with crystallized walls

• the ability to assist photoinduced water-splitting, their activities are not promising [10][11]. The successful synthesis of the present novel nanoarchitectured MgTa2O6 film significantly promoted the potential property of MgTa2O6 as a photocatalyst, which we believe could find practical applications

Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94

• ; Introduction Photocatalytic degradation of pollutants is attracting increasing attention. In this context, anatase-phase titanium dioxide is regarded as the photocatalyst of choice, due to its low cost, nontoxicity, and relatively high efficiency, which make it suitable not only for air and water

• decontamination [1][2] but also for self-cleaning applications [3]. The general scheme for the photocatalytic destruction of organics involves the excitation of this semiconductor by irradiation with suprabandgap photons and migration of the electron–hole pairs to the surface of the photocatalyst, where the holes

• applied bias acted to push photogenerated holes to the external surface of the TiO2 layer while pulling the photogenerated electrons to the platinum electrons, thus limiting the recombination rate. Indeed, the degradation rate constant was found to increase as the positive bias on the photocatalyst was

Approaches to nanostructure control and functionalizations of polymer@silica hybrid nanograss generated by biomimetic silica mineralization on a self-assembled polyamine layer

• Jian-Jun Yuan and
• Ren-Hua Jin

Beilstein J. Nanotechnol. 2011, 2, 760–773, doi:10.3762/bjnano.2.84

• –superhydrophilic) by surface hydrophobic treatment and UV irradiation. The anatase titania component in the nanograss film acts as a highly efficient photocatalyst for the decomposition of the low-surface-energy organic components attached to the nanosurface. The ease with which the nanostructure can be controlled

Enhanced visible light photocatalysis through fast crystallization of zinc oxide nanorods

• Sunandan Baruah,
• Mohammad Abbas Mahmood,
• Myo Tay Zar Myint,
• Tanujjal Bora and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2010, 1, 14–20, doi:10.3762/bjnano.1.3

• sites arising from oxygen nonstoichiometry, has emerged to be an efficient photocatalyst material compared to other metal oxides [8][9][10]. ZnO exhibits comparatively higher reaction and mineralization rates [11] and can generate hydroxyl ions more efficiently than titania (TiO2) [12]. Surface area and