Effects of swift heavy ion irradiation on structural, optical and photocatalytic properties of ZnO–CuO nanocomposites prepared by carbothermal evaporation method

• Sini Kuriakose,
• D. K. Avasthi and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2015, 6, 928–937, doi:10.3762/bjnano.6.96

• of CuO. This helps to inhibit the recombination of photogenerated electrons and holes and improves the charge separation efficiency. The oxygen molecules adsorbed on the photocatalyst form superoxide anion radicals (•O2−) due to their interaction with electrons in the conduction band of ZnO. Surface

Observation of a photoinduced, resonant tunneling effect in a carbon nanotube–silicon heterojunction

• Carla Aramo,
• Antonio Ambrosio,
• Michelangelo Ambrosio,
• Maurizio Boscardin,
• Paola Castrucci,
• Michele Crivellari,
• Marco Cilmo,
• Maurizio De Crescenzi,
• Francesco De Nicola,
• Emanuele Fiandrini,
• Valentina Grossi,
• Pasqualino Maddalena,
• Maurizio Passacantando,
• Sandro Santucci,
• Manuela Scarselli and
• Antonio Valentini

Beilstein J. Nanotechnol. 2015, 6, 704–710, doi:10.3762/bjnano.6.71

• -based devices have been attributed to the photon-induced generation of charge carriers in single-wall CNTs and the subsequent charge separation across the carbon nanotube–metal contact interface [11]. To the best of our knowledge, there is a lack of measurements in the UV region [8], and moreover, there

Tm-doped TiO₂ and Tm₂Ti₂O₇ pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

• Desiré M. De los Santos,
• Javier Navas,
• Teresa Aguilar,
• Antonio Sánchez-Coronilla,
• Concha Fernández-Lorenzo,
• Rodrigo Alcántara,
• Jose Carlos Piñero,
• Ginesa Blanco and
• Joaquín Martín-Calleja

Beilstein J. Nanotechnol. 2015, 6, 605–616, doi:10.3762/bjnano.6.62

• charge separation efficiency. The process of catalytic photodegradation of organic compounds can be described as follows: a continuous irradiation (with an energy higher than band gap energy) of an aqueous semiconductor dispersion excites an electron from the valence band to the conduction band, creating

• the recombination of the electron–hole pairs, because the recombination is usually much easier than the subsequent steps required for organic degradation [10]. In our case, the heterojunction that exists at the interface of the mixed phases in the doped samples promotes charge separation, that is, the

• separation of electron–hole pairs. This has been reported previously for NaTaO3/Na2Ta2O6 phases [43]. An efficient charge separation implies low recombination, and this has been observed from the Raman results for the pyrochlore-based samples. Moreover, the higher photocatalytic activity in the ordered

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• orthogonal functionalization of the surfaces [30][40][41]. In addition to the extrinsic characteristics arising from exploiting the anisotropy, efficient charge separation [42], magnetic interaction [43], or spin-polarization transfer [44] at the interface of the hetero-nanoparticle can be realized by

• conjugation to Ag nanoparticles when combined to form Ag@Fe3O4 dumbbell-like hetero-nanoparticles [47]. Moreover, plasmonic photocatalysts combine two prominent features: a Schottky junction enhancing charge separation and surface plasmon resonance, which is responsible for strong absorption of visible light

Donor–acceptor graphene-based hybrid materials facilitating photo-induced electron-transfer reactions

• Anastasios Stergiou,
• Georgia Pagona and
• Nikos Tagmatarchis

Beilstein J. Nanotechnol. 2014, 5, 1580–1589, doi:10.3762/bjnano.5.170

• such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for

• proceeds via nitrenes as generated upon the thermal (or photochemical) decomposition of azides and the liberation of dinitrogen. Characterization, charge-separation and incident-photon-to-current efficiency Raman spectroscopy is an extremely useful tool for characterizing graphene-based materials. Pristine

• , charge-separation takes place and the efficiency of the whole process is governed by how fast or slow the recombination of charges occurs. A schematic description of such a process, which sometimes may be quite complex involving triplet states as derived upon intersystem crossing, is presented in Figure

An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals

• Parul Chawla,
• Son Singh and
• Shailesh Narain Sharma

Beilstein J. Nanotechnol. 2014, 5, 1235–1244, doi:10.3762/bjnano.5.137

• donor and the charge separation mechanism across the donor–acceptor interface from the extent of crystallinity of the chalcopyrite semiconductors (CISe/CIGSe/CZTSe). Quaternary CZTSe chalcopyrites with their high crystallinity and controlled morphology in conjunction with regioregular P3HT polymer is an

• , a charge-separation at donor–acceptor heterojunctions is a key process, which takes center stage in determining the energy conversion efficiency of hybrid photovoltaics. Hybrid solar cells enjoy an advantage of intrinsically high carrier mobility, which is caused by inorganic materials dispersed in

• polymer P3HT, the generation of excitons takes place (process 1). The excitons then diffuse to the polymer–chalcopyrite interface where charge separation occurs (process 2). The overall energetic driving force ∆E for the electron transfer from the donor to the acceptor depends on the energy difference

Functionalized nanostructures for enhanced photocatalytic performance under solar light

• Liejin Guo,
• Dengwei Jing,
• Maochang Liu,
• Yubin Chen,
• Shaohua Shen,
• Jinwen Shi and
• Kai Zhang

Beilstein J. Nanotechnol. 2014, 5, 994–1004, doi:10.3762/bjnano.5.113

• efficient hydrogen evolution. Generally, MCM-41 is not photo-reactive. But it can be activated by coupling with a semiconductor or doping a transitional metal. Figure 3 shows the proposed charge separation mechanism within a representative transitional metal-containing molecular sieve photocatalyst [21]. In

• simple one-step hydrothermal method [33]. As schematically illustrated in Figure 5, the CdS nanoparticle was intimately enwrapped by the TNTs, resulting in a remarkably enhanced charge separation efficiency and thereby photocatalytic hydrogen production activity. The similar enwrapped structure can also

• accumulate on high-indexed facets, while photogenerated holes tended to migrate to {100} facets, leading to an efficient spatial charge separation and thereby enhanced photocatalytic hydrogen production from reforming of glucose over the Cu2O polyhedron [45]. The origin of the charge separation on different

Optical modeling-assisted characterization of dye-sensitized solar cells using TiO₂ nanotube arrays as photoanodes

• Jung-Ho Yun,
• Il Ku Kim,
• Yun Hau Ng,
• Lianzhou Wang and
• Rose Amal

Beilstein J. Nanotechnol. 2014, 5, 895–902, doi:10.3762/bjnano.5.102

• . Figure 5 shows the calculated electric field intensity of the DSSCs with different TNT lengths by using GTMM. The electric field formed between active layers of solar cells triggers the charge separation of electron and hole generated in the solar cell system. The electric field intensity in Figure 5a

• shows the behavior of charge separation occurring at an interface between multi-layers as a function of the position in the device. The position in the device refers to the distance from the first layer (Pt layer) illuminated by light. Herein, for the modeling analysis, the configuration of DSSCs was

• dye is usually considered as a volume. Therefore, with the longer TNT array, the larger magnitude of the electric field intensity and the thicker electric field-valid layer contribute to the higher light harvesting with an enhanced charge separation. This is well matched with the Jsc and IPCE results

Biomolecule-assisted synthesis of carbon nitride and sulfur-doped carbon nitride heterojunction nanosheets: An efficient heterojunction photocatalyst for photoelectrochemical applications

• Hua Bing Tao,
• Hong Bin Yang,
• Jiazang Chen,
• Jianwei Miao and
• Bin Liu

Beilstein J. Nanotechnol. 2014, 5, 770–777, doi:10.3762/bjnano.5.89

• ). This type-II band alignment means that once CN and CNS are electronically coupled, a well-matched band structure for charge separation will be formed. In this case, the photogenerated electrons are transferred from CN to CNS, while the photogenerated holes are transferred from CNS to CN, leading to an

• improved charge separation. To test our hypothesis, we designed a strategy to construct CN/CNS heterostructures. In our method, we firstly grow CNS nanosheets by using a biomolecule-assisted pyrolysis method, followed by growing CN on preformed CNS nanosheets to form a well-mixed CN/CNS heterostructure

• is worth mentioning that the shape of the three EQE curves are similar with the same cut off at nearly 470 nm, indicating that the enhanced photocurrent of CN/CNS heterostructure mainly comes from improved charge separation at the CN/CNS heterojunction interface. Conclusion In conclusion, we have

Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

• Hongjun Chen and
• Lianzhou Wang

Beilstein J. Nanotechnol. 2014, 5, 696–710, doi:10.3762/bjnano.5.82

• quantum dots, plasmonic metal nanostructures, and carbon nanostructures for coupling with wide-bandgap transition metal oxides to design better visible-light active photocatalysts. The underlying mechanisms of the composite photocatalysts, e.g., the light-induced charge separation and the subsequent

• –hole pairs. Then, if coupled with a transition metal oxide, the photogenerated electrons can be easily transferred from the CB minimum of the photosensitizer or LUMO to that of a transition metal oxide. Thus the efficient charge separation in the metal oxide-photosensitizer nanocomposites facilitates

• adjacent TiO2, while the photogenerated holes stay in the VB of CdS. Consequently, the charge separation is improved, and the separated electrons and holes are continually involved in the following reduction and oxidation reactions. The charges transfer scheme is shown in Figure 2. Zhang et al. have

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. Figure 6 clearly shows a significant enhancement of photocurrent after the loading of GQDs, indicating the charge separation efficiency of TNAs is greatly enhanced. The stable current reveals that GQDs are covalently bonded to TNAs instead of adsorbed onto the surface of TNAs. The

• 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

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

• charge separation in ZnO. When ZnO absorbs photons of energy greater than or equal to its band gap, electrons are promoted from its valence band to conduction band, creating an equal number of holes in the valence band. Since the energy level of conduction band of ZnO is higher than the Fermi level of Ag

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

• crystallinity, the improved absorption in the visible-light region, as well as the presence of Ag species. Regarding the latter it has been proposed that both Ag0 and Ag+ played an important role in facilitating the charge separation and suppressing the recombination of photoexcited charge carries [18][19

Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

• Subas K. Muduli,
• Songling Wang,
• Shi Chen,
• Chin Fan Ng,
• Cheng Hon Alfred Huan,
• Tze Chien Sum and
• Han Sen Soo

Beilstein J. Nanotechnol. 2014, 5, 517–523, doi:10.3762/bjnano.5.60

• and solar energy absorption processes by providing higher surface areas and more effective charge separation in semiconductor materials on the nanoscale. In fact, the commercially available Degussa P25 mixed-phase TiO2 is commonly employed as a benchmark in photocatalysis for applications ranging from

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

• noble metal (e.g., Pt) nanoparticles as co-catalysts that can act as electron-sinks to achieve effective charge separation on TiO2 [7][8][9][10][11]. Dye-sensitization has been widely used to enable visible light harvesting by wide band gap semiconductors. Since the seminal work reported by O’Regan and

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

• 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

Template based precursor route for the synthesis of CuInSe₂ nanorod arrays for potential solar cell applications

• Mikhail Pashchanka,
• Jonas Bang,
• Niklas S. A. Gora,
• Ildiko Balog,
• Rudolf C. Hoffmann and
• Jörg J. Schneider

Beilstein J. Nanotechnol. 2013, 4, 868–874, doi:10.3762/bjnano.4.98

• unique ability for independent adjustment of light absorption (by nanowire length) and charge separation (by nanowire diameter). Nanowire-based photovoltaic layers will allow the fabrication of low-cost small size energy devices with economical use of materials. Very recently, Schoen et al. reported the

Kelvin probe force microscopy of nanocrystalline TiO₂ photoelectrodes

• Alex Henning,
• Gino Günzburger,
• Res Jöhr,
• Yossi Rosenwaks,
• Biljana Bozic-Weber,
• Catherine E. Housecroft,
• Edwin C. Constable,
• Ernst Meyer and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2013, 4, 418–428, doi:10.3762/bjnano.4.49

• linear dependency on the light intensity up to a value of −250 mV. A logarithmic dependence on the light intensity would be typical for a charge separation at a built-in potential, for instance at the surface space-charge region. However, the linear dependence indicates a charge separation, which is

Photocatalytic antibacterial performance of TiO₂ and Ag-doped TiO₂ against S. aureus. P. aeruginosa and E. coli

• Kiran Gupta,
• R. P. Singh,
• Ashutosh Pandey and
• Anjana Pandey

Beilstein J. Nanotechnol. 2013, 4, 345–351, doi:10.3762/bjnano.4.40

• into the TiO2 matrix. The results observed from this study, alongside a previous study [22] , suggest that the doping of metal and metal oxides on the surface of TiO2 nanoparticles increases the value of the e−–h+ charge separation by decreasing the band-gap energy, and leads to a delay in the

Near-field effects and energy transfer in hybrid metal-oxide nanostructures

• Ulrich Herr,
• Balati Kuerbanjiang,
• Cahit Benel,
• Giorgos Papageorgiou,
• Manuel Goncalves,
• Johannes Boneberg,
• Paul Leiderer,
• Paul Ziemann,
• Peter Marek and
• Horst Hahn

Beilstein J. Nanotechnol. 2013, 4, 306–317, doi:10.3762/bjnano.4.34

• center, and conversion to other forms of energy by charge separation and transfer. This may be achieved by utilizing hybrid nanostructures, which combine metallic and nonmetallic components. Metallic nanostructures can interact strongly with light. Plasmonic excitations of such structures can cause local

Horizontal versus vertical charge and energy transfer in hybrid assemblies of semiconductor nanoparticles

• Gilad Gotesman,
• Rahamim Guliamov and
• Ron Naaman

Beilstein J. Nanotechnol. 2012, 3, 629–636, doi:10.3762/bjnano.3.72

• . Keywords: charge transfer; energy transfer; nanoparticles; organic linker; quantum dots; Introduction Self-assembled structures of semiconductor nanoparticles (NPs) are viewed as a possible avenue for producing photovoltaic devices with efficient collection of light and charge separation processes [1

• type of transfer process. Wu et al. studied charge separation in type-II heterojunction assemblies of CdSe–CdTe NPs as a function of linker length [23]. They found that for longer linkers, the charge transfer efficiency is smaller. In another study, photogenerated exciton dissociation in PbS NP thin

• . This is a tunneling-based effect; therefore, it strongly depends on the length of the linker (as seen in Figure 2a). Dithiolated-linker length-dependent PL and PL-lifetime quenching, owing to charge separation within the NPs layer, was reported previously for PbS NP thin films [24]. To validate this

Junction formation of Cu₃BiS₃ investigated by Kelvin probe force microscopy and surface photovoltage measurements

• Fredy Mesa,
• William Chamorro,
• William Vallejo,
• Robert Baier,
• Thomas Dittrich,
• Alexander Grimm,
• Martha C. Lux-Steiner and
• Sascha Sadewasser

Beilstein J. Nanotechnol. 2012, 3, 277–284, doi:10.3762/bjnano.3.31

• the influence of defect states below the band gap on charge separation and a surface-defect passivation by the In2S3 buffer layer. Our findings indicate that Cu3BiS3 may become an interesting absorber material for thin-film solar cells; however, for photovoltaic application the band bending at the

• compare the SPV between the different samples. This is shown in the upper panel of Figure 3. While the etched Cu3BiS3 surface and the CdS and ZnS buffer layers exhibit a positive SPV, only the In2S3 buffer layer exhibits a negative SPV. This corresponds to charge separation due to band bending at the

• , the spectrum of the light intensity is shown for comparison. There are distinct shoulders and peaks in the amplitude spectra, which are related to the onset of electronic transitions from which charge separation is possible and that depend also on the light intensity. A normalization of SPV spectra to

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

• . A claim was made that similar paths yielding long-lived charge separation situations may be relevant also in natural photosynthetic systems, and should be considered in the development of dye-sensitized solar cells. In certain cases, feasibility studies with TiO2-containing systems were later

Highly efficient ZnO/Au Schottky barrier dye-sensitized solar cells: Role of gold nanoparticles on the charge-transfer process

• Tanujjal Bora,
• Htet H. Kyaw,
• Soumik Sarkar,
• Samir K. Pal and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2011, 2, 681–690, doi:10.3762/bjnano.2.73

• improve the device performance through better charge separation in the photoelectrodes. In this regards, several reports have been previously published [19][20][21][22][23] demonstrating the rapid charge transfer and improved charge separation upon the incorporation of Au nanoparticles in ZnO- or TiO2