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

• some donor–acceptor graphene-based hybrids, will be discussed. Keywords: donor–acceptor; electron-transfer; functionalization; graphene; photophysical properties; Introduction Among the outstanding forms of carbon nanostructures, graphene, a single layer of carbon, is a newly available material

• graphene, in which the organic unit is tightly attached on the graphene network, is the method of choice for preparing novel donor–acceptor hybrid materials that can potentially facilitate photo-induced electron-transfer phenomena. Single-layer, bilayer and oligo-layer graphene sheets have been utilized to

• reaction mechanism involves an electron transfer from graphene to the diazonium salt, resulting in the formation of a radical aryl unit, which subsequently adds to the sp2-carbon lattice of graphene; Addition of azides forming aziridine adducts onto graphene [41][42][43]. The particular functionalization

Ionic liquid-assisted formation of cellulose/calcium phosphate hybrid materials

• Ahmed Salama,
• Mike Neumann,
• Christina Günter and
• Andreas Taubert

Beilstein J. Nanotechnol. 2014, 5, 1553–1568, doi:10.3762/bjnano.5.167

• towards the triggered nucleation of calcium phosphate on chitosan cast films [19]. Mineralization is induced by photoexcitation of fluorescein molecules grafted to the chitosan films. The authors claim that the formation of local positive charges by electron transfer from the fluorophore to reactive

Current state of laser synthesis of metal and alloy nanoparticles as ligand-free reference materials for nano-toxicological assays

• Christoph Rehbock,
• Jurij Jakobi,
• Lisa Gamrad,
• Selina van der Meer,
• Daniela Tiedemann,
• Ulrike Taylor,
• Wilfried Kues,
• Detlef Rath and
• Stephan Barcikowski

Beilstein J. Nanotechnol. 2014, 5, 1523–1541, doi:10.3762/bjnano.5.165

• process. Certainly, particles in these transition states may unpredictably react with biomolecules due to electron transfer processes in case these biomolecules are present in situ. However, these excited states have a very short lifetime and primary particle formation is estimated to be finished within

Liquid fuel cells

• Grigorii L. Soloveichik

Beilstein J. Nanotechnol. 2014, 5, 1399–1418, doi:10.3762/bjnano.5.153

• hydrogen is oxidized fast, e.g., by using active porous electrodes, the total number of transferred electrons is still eight as was shown by rotating disk electrode experiments on an Au electrode [168]. The electrooxidation of borohydride anions is a multi-step electron transfer process with competing

Effects of palladium on the optical and hydrogen sensing characteristics of Pd-doped ZnO nanoparticles

• Anh-Thu Thi Do,
• Hong Thai Giang,
• Thu Thi Do,
• Ngan Quang Pham and
• Giang Truong Ho

Beilstein J. Nanotechnol. 2014, 5, 1261–1267, doi:10.3762/bjnano.5.140

• controls the gas sensing characteristics, have been reported in ZnO films [23]. The sensitivity and selectivity characteristics of the gas sensor are associated with the deep hole-trap states and vacancies on the ZnO surface by the electron transfer mechanism [23][24]. The Pd metal nanoparticles modify the

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

• in Figure 5a, a more pronounced decrease of the emission intensity of the P3HT:CZTSe composite is observed with an increasing CZTSe concentration compared to P3HT:CISe and P3HT:CIGSe polymer nanocomposites. This corroborates the suggestion that a more efficient electron transfer is taking place

• 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

Enhanced photocatalytic hydrogen evolution by combining water soluble graphene with cobalt salts

• Jing Wang,
• Ke Feng,
• Hui-Hui Zhang,
• Bin Chen,
• Zhi-Jun Li,
• Qing-Yuan Meng,
• Li-Ping Zhang,
• Chen-Ho Tung and
• Li-Zhu Wu

Beilstein J. Nanotechnol. 2014, 5, 1167–1174, doi:10.3762/bjnano.5.128

• oxide; EY: eosin Y). Graphene enhances the catalytic efficiency of hydrogen evolution remarkably. By using transient photovoltage and photocurrent techniques [48][49][50], the function of graphene was examined. More recently, our group has demonstrated the efficient forward electron-transfer mediated by

• not only its high conductivity for electron transfer, but also its great dispersibility to act as a platform to anchor catalysts. The photocatalytic hydrogen evolution was evaluated under irradiation at 525 nm by using TEOA as a sacrificial donor and EY as a photosensitizer, while cobalt salts and G

• demonstrated that G-SO3 acts as an electron mediator of EY and platinum nanoparticles co-catalyst, we consider that in the current study the electron transfer process from the EY radical anion (EY•−) to G-SO3 or in situ formed-Co(TEOA)22+ would be facilitated. Similar to the storage phenomenon observed in

DFT study of binding and electron transfer from colorless aromatic pollutants to a TiO₂ nanocluster: Application to photocatalytic degradation under visible light irradiation

• Corneliu I. Oprea,
• Petre Panait and
• Mihai A. Gîrţu

Beilstein J. Nanotechnol. 2014, 5, 1016–1030, doi:10.3762/bjnano.5.115

• efficient photocatalytic degradation of pollutants under visible light irradiation has to meet similar requirements to the ones of the dyes in Grätzel cells. In particular, the anchoring mode of the pollutant to the TiO2 surface influences the electron transfer [17]. The most commonly used anchoring group

• the likelihood of the electron transfer. In Marcus’ theory of the electron transfer [51][52][53] an important factor in the expression of the electron transfer rate is the electronic matrix element describing the electronic coupling between the excited state of the pollutant and a state in the

• kinetics of the electron transfer from an excited dye to the titania nanoparticle may be influenced by the vibrational motion of nuclei. The vibronic perturbation, due to the interplay of electron–electron interactions and the internal vibrations of the benzene derivative, may facilitate the charge

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

• confinement effect is considered to be crucial. As the recombination of photogenerated charges within TiO2 could be neglected, the rate-determining step for photocatalytic reaction is the electron transfer from TiO2 to H+ in the solution. Therefore, deposition of Pt as cocatalyst is indispensable for an

• as Cr or/and Ti incorporation in MCM-41. Active visible light absorption sites could be generated in MCM-41 due to transitional metal doping. It was found that the highly dispersed Cr ions within MCM 41 could be easily excited by visible light irradiation due to the electron transfer from O2− to Cr6

• conduction band of ZTP could be continuously controlled by regulating the Zr/Ti ratio. At the optimal Ti to Zr ratio of 3, the energy difference between conduction bands of CdS and ZTP could ensure a large driving force for fluent electron transfer from CdS to ZTP, while the electron localized on the ZTP

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

• parameters of the DSSCs, electrochemical impedance spectroscopy (EIS) offers valuable information. Figure 4 shows the Bode phase plots and the Nyquist plots obtained from electron transfer at the TiO2 and electrolyte interface under a solar simulator of AM 1.5. Figure 4a shows the negative shift of the

Volcano plots in hydrogen electrocatalysis – uses and abuses

• Paola Quaino,
• Fernanda Juarez,
• Elizabeth Santos and
• Wolfgang Schmickler

Beilstein J. Nanotechnol. 2014, 5, 846–854, doi:10.3762/bjnano.5.96

• modern volcano plots is the only metal on the descending branch. There is a parallelism between the concept of volcano plots in catalysis and outer sphere electron transfer reactions. According to Marcus’ theory [6] a plot of the reaction rate versus the reaction free energy ΔG should pass through a

• maximum when ΔG ≈ −λ, where λ is the energy of solvent reorganisation of the reaction, and fall off for more exergonic reactions; the descending branch is known as the Marcus inverted region. While there are many electron transfer reaction which clearly show the ascending branch, there are very few

• at the equilibrium potential; have a d band which spans the Fermi level; have a strong and long-ranged interaction between the d band and the hydrogen 1s orbital. A long range is important, because the electron transfer to the proton occurs at a certain distance, of the order of 0.5 Å, from the

Enhancement of photocatalytic H₂ evolution of eosin Y-sensitized reduced graphene oxide through a simple photoreaction

• Weiying Zhang,
• Yuexiang Li,
• Shaoqin Peng and
• Xiang Cai

Beilstein J. Nanotechnol. 2014, 5, 801–811, doi:10.3762/bjnano.5.92

• -RGO24/Pt for hydrogen evolution rises up to 12.9% under visible light irradiation (λ ≥ 420 nm), and 23.4% under monochromatic light irradiation at 520 nm. Fluorescence spectra and transient absorption decay spectra of the EY-sensitized RGO confirm that the electron transfer ability of RGO increases with

• composites, a nanographene shell on a TiO2 core and TiO2 nanoparticles on a graphene sheet, exhibit a higher photocatalytic H2 evolution than TiO2 under UV irradiation. This can be attributed to an efficient electron transfer from TiO2 to graphene [9][10]. Interestingly, single reduced graphene oxide itself

• photo-induced electron transfer from the excited dye molecules to RGOx. The slight blue shift suggests that an intermolecular π-π stacking interaction between RGO24 and EY is stronger than the interaction between GO and EY [20]. To further confirm the increased ability to transfer electrons between RGOx

An analytical approach to evaluate the performance of graphene and carbon nanotubes for NH₃ gas sensor applications

• Elnaz Akbari,
• Vijay K. Arora,
• Aria Enzevaee,
• Mohamad. T. Ahmadi,
• Mehdi Saeidmanesh,
• Mohsen Khaledian,
• Hediyeh Karimi and
• Rubiyah Yusof

Beilstein J. Nanotechnol. 2014, 5, 726–734, doi:10.3762/bjnano.5.85

• zero bandgap energy, graphene has a high electron mobility at room temperature. The electron transfer in graphene is 100 times faster than that in silicon. A zero band gap with massless Dirac fermions makes graphene theoretically lossless, making it a perfect two-dimensional (2D) semiconductor [19][20

Visible light photooxidative performance of a high-nuclearity molecular bismuth vanadium oxide cluster

• Johannes Tucher and
• Carsten Streb

Beilstein J. Nanotechnol. 2014, 5, 711–716, doi:10.3762/bjnano.5.83

• for the photoexcited cluster 1 [31][47], see Table 1. Our current hypothesis is that 3O2 acts as a triplet radical quencher that interacts with the reactive triplet state of the photoexcited cluster molecule by energy and/or electron transfer, resulting in an overall reduced photoreactivity of 1 under

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

• conducted direct femtosecond measurements of the electron transfer process from CdS to TiO2 and found that this process could be completed on a time constant of 2 picoseconds, resulting in a significantly slower recombination of the charge carriers generated upon light absorption in CdS [19]. Improved

• the band alignment between CdS and CdSe, the co-sensitized ZnO nanowire arrayed photoanode exhibited almost the entire visible-light absorption and fast electron transfer from CdSe quantum dots to ZnO nanowires and thereby the IPCE value can reach 45% at 0 V vs Ag/AgCl, as demonstrated in Figure 4c

• evaluation of size dependent electron transfer rates in CdSe–TiO2 semiconductor heterostructures [56]. Based on femtosecond transient absorption measurement it was found that the CB of CdSe quantum dots become more negative and the energy difference between the CB of CdSe and TiO2 is much larger with

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

• 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

• –ZnO hybrid structure, electrons flow from ZnO nanostructures to Ag nanoparticles. This way Ag nanoparticles act as efficient sinks for the photogenerated electrons, preventing their recombination with holes. This process, known as the direct electron transfer from semiconductor to the plasmonic

Analytical development and optimization of a graphene–solution interface capacitance model

• Hediyeh Karimi,
• Rasoul Rahmani,
• Reza Mashayekhi,
• Leyla Ranjbari,
• Amir H. Shirdel,
• Niloofar Haghighian,
• Parisa Movahedi,
• Moein Hadiyan and
• Razali Ismail

Beilstein J. Nanotechnol. 2014, 5, 603–609, doi:10.3762/bjnano.5.71

• ]. Therefore, the electron transfer in graphene is expected to be 100 times faster than that in silicon. Other advantages of graphene, which make it a perfect semiconductor is its massless Dirac fermion structure with zero band gap (graphene is considered to be theoretically lossless) [19]. Compared to silicon

CoPc and CoPcF₁₆ on gold: Site-specific charge-transfer processes

• Fotini Petraki,
• Heiko Peisert,
• Johannes Uihlein,
• Umut Aygül and
• Thomas Chassé

Beilstein J. Nanotechnol. 2014, 5, 524–531, doi:10.3762/bjnano.5.61

• photoemission final state. Therefore, a change of the spectral shape can be attributed to (i) an electron transfer from the metal surface, leading to a reduction of the Co(II) ion to Co(I), (ii) by a redistribution of the d-electrons, or both (i) and (ii). Both the appearance of an interface component and the

• , implies that the phthalocyanine macrocycle is positively charged compared to molecules in the bulk. This means, while we observe an electron transfer to Co of CoPcF16, an opposite charge transfer is observed between the macrocycle of the molecule and the substrate, i.e., the charge transfer 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

• -efficient photocatalytic generation of hydrogen under visible-light irradiation. In this rational design of the ternary structure, the TiO2 particle acts as a bridge that allows for the effective electron transfer pathway of excited ErB→TiO2→Pt. Importantly, we found that when the TiO2 bridges are excited

• the excitation of ErB and TiO2, which plays an important role in the photocatalytic hydrogen generation. The observed synergic effect could be attributed to the electron transport in TiO2 particles. Since the dye-sensitization induces an electron transfer from the excited ErB to TiO2, these electrons

• the conductivity of TiO2. Thereby, the vectored electron transfer from ErB to the core Pt particle via TiO2 bridges becomes more effective, which leading to enhanced yield of H2. The principle is depicted in Figure 5, and the energy diagram is shown in Figure S3 (Supporting Information File 1). In

A catechol biosensor based on electrospun carbon nanofibers

• Dawei Li,
• Zengyuan Pang,
• Xiaodong Chen,
• Lei Luo,
• Yibing Cai and
• Qufu Wei

Beilstein J. Nanotechnol. 2014, 5, 346–354, doi:10.3762/bjnano.5.39

• fast and effective methods to detect phenolic compounds. Laccase (benzendiol:oxygen oxidoreductases; EC 1.10.3.2), a multicopper oxidase widely distributed in plant and fungal species, can reduce oxygen directly to water through a four-electron transfer step, and this chemical reaction does not produce

• surface morphology of the laccase–Nafion–ECNFs/GCE. It can be clearly seen that most of the short fibers were embedded into the laccase. Here, the short fibers may play a role of connecting the active center of laccase and the surface of GCE, which may be favorable for the electron transfer. Structure and

• 0.05 to 0.3 V·s−1. It can be clearly seen that a pair of stable and well-defined quasi-reversible anodic and cathodic peaks occur, which can be attributed to the direct electron transfer between the laccase and the GCE. Besides, the anodic peak currents were larger than the peak cathodic currents

Atomic layer deposition, a unique method for the preparation of energy conversion devices

• Julien Bachmann

Beilstein J. Nanotechnol. 2014, 5, 245–248, doi:10.3762/bjnano.5.26

• interface. This electron transfer, the most fundamental energy-converting single event, occurs at the interface between two phases, which can have various identities depending on the type of device. In most solar cells these two phases are two solid semiconductors, in batteries and fuel cells they are

Change of the work function of platinum electrodes induced by halide adsorption

• Florian Gossenberger,
• Tanglaw Roman,
• Katrin Forster-Tonigold and
• Axel Groß

Beilstein J. Nanotechnol. 2014, 5, 152–161, doi:10.3762/bjnano.5.15

• the halogen adlayer, the contribution of the electron transfer to the surface dipole moment can be quantified, where is the average distance of the halogen adatoms from the metal surface. We combine all other parts contributing to the total dipole moment in the term Δμpol, because it involves

• function change on platinum is large because of the high work function of clean platinum, which favors only a small electron transfer to the halogen adatoms compared with other metals. Therefore, polarization effects that reverse the dipole moment attributed to charge transfer are more pronounced than on

The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

• Jakob G. Howalt and
• Tejs Vegge

Beilstein J. Nanotechnol. 2014, 5, 111–120, doi:10.3762/bjnano.5.11

• dissociation barriers (1.8 eV) of N2 not taking place at the surface. For the purposes of analyzing the reduction of oxygen, a two-step electron-transfer process was assumed and simulated using the Heyrovsky-type [19] reaction. In an acidic environment, the reaction comprises of these elementary reaction steps

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

• photosensitized solar cells with high quantum yields [1][2][3][4] and the photocatalytic degradation of pollutants [5][6]. CdS, currently used as an efficient visible-light sensitizer, is a semiconductor that possesses a small band gap (2.4 eV) and suitable potential energies. The electron transfer between QDs