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Butburee T, Sun Z, Centeno A, et al., 2019, Improved CO<sub>2</sub> photocatalytic reduction using a novel 3-component heterojunction (vol 62, pg 426, 2019), NANO ENERGY, Vol: 63, ISSN: 2211-2855
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- Citations: 7
Wang K, Li C, Li Z, et al., 2019, A facile fabrication strategy for anisotropic photonic crystals using deformable spherical nanoparticles., Nanoscale, Vol: 11, Pages: 14147-14154
A 2D anisotropic photonic crystal (APC) of bowl-shaped nanoparticles has been fabricated using deformable spherical nanoparticles. The prepared 2D isotropic photonic crystal (IPC) of spherical nanoparticles is transformed into a 2D APC by a chemical etching process, in which the interiors of the spherical nanoparticles are preferentially dissolved to eventually form a bowl-like morphology. Due to the accurate and controllable deformability of the spherical nanoparticles, the arrangement and orientations of the bowl-shaped nanoparticles are highly ordered and uniform. The morphology, optical properties and surface wettability of the 2D APC are all distinct from those of the prepared 2D IPC. This facile strategy provides an easy and low-cost way to fabricate highly ordered and uniform APCs.
Butburee T, Sun Z, Centeno A, et al., 2019, Improved CO<inf>2</inf> photocatalytic reduction using a novel 3-component heterojunction, Nano Energy, Vol: 62, Pages: 426-433, ISSN: 2211-2855
A new class of three-component photocatalyst system is designed with plasmonic AuCu nanoprisms embedded between a porous single crystalline TiO2 nanoplate thin film and polyhedral zeolitic imidazolate frameworks (ZIF-8) nanoparticles for enhanced CO2 photocatalytic reduction. The ZIF-8 plays a role of CO2 capture to enhance the reactant concentration on the catalyst, while the AuCu nanoprisms function mainly as a mediator to improve the charge density at the interfaces and facilitate the charge transfer to the CO2 adsorption sites on ZIF-8 for subsequent CO2 reduction. The reactant CO2 could be not only readily collected on the newly designed catalyst, but also more efficiently converted to CO and CH4. As a result, compared to the reference sample of two-component system of TiO2 and ZIF-8 with a CO2 conversion rate of 12.5 μmol h−1 g−1, the new three-component photocatalyst exhibited a nearly 7-fold improvement in CO2 photocatalytic reduction performance with CO2 conversion reaching an outstanding value of 86.9 μmol h−1 g−1, highlighting the importance of rational heterojunction design in facilitating reactant adsorption, charge transfer and reaction processes in photocatalysis.
Ruenraroengsak P, Kiryushko D, Theodorou IG, et al., 2019, Frizzled-7-targeted delivery of zinc oxide nanoparticles to drug-resistant breast cancer cells, Nanoscale, Vol: 11, Pages: 12858-12870, ISSN: 2040-3364
There is a need for novel strategies to treat aggressive breast cancer subtypes and overcome drug resistance. ZnO nanoparticles (NPs) have potential in cancer therapy due to their ability to potently and selectively induce cancer cell apoptosis. Here, we tested the in vitro chemotherapeutic efficacy of ZnONPs loaded via a mesoporous silica nanolayer (MSN) towards drug-sensitive breast cancer cells (MCF-7: estrogen receptor-positive, CAL51: triple-negative) and their drug-resistant counterparts (MCF-7TX, CALDOX). ZnO-MSNs were coated on to gold nanostars (AuNSs) for future imaging capabilities in the NIR-II range. Electron and confocal microscopy showed that MSN-ZnO-AuNSs accumulated close to the plasma membrane and were internalized by cells. High-resolution electron microscopy showed that MSN coating degraded outside the cells, releasing ZnONPs that interacted with cell membranes. MSN-ZnO-AuNSs efficiently reduced the viability of all cell lines, and CAL51/CALDOX cells were more susceptible than MCF7/MCF-7-TX cells. MSN-ZnO-AuNSs were then conjugated with the antibody to Frizzled-7 (FZD-7), the receptor upregulated by several breast cancer cells. We used the disulphide (S-S) linker that could be cleaved with a high concentration of glutathione normally observed within cancer cells, releasing Zn2+ into the cytoplasm. FZD-7 targeting resulted in approximately three-fold amplified toxicity of MSN-ZnO-AuNSs towards the MCF-7TX drug-resistant cell line with the highest FZD-7 expression. This study shows that ZnO-MSs are promising tools to treat triple-negative and drug-resistant breast cancers and highlights the potential clinical utility of FZD-7 for delivery of nanomedicines and imaging probes specifically to these cancer types.
Pang JS, Theodorou IG, Centeno A, et al., 2019, Tunable three-dimensional plasmonic arrays for large near-infrared fluorescence enhancement, ACS Applied Materials and Interfaces, Vol: 11, Pages: 23083-23092, ISSN: 1944-8244
Metal-enhanced fluorescence (MEF), resulting from the near-field interaction of fluorophores with metallic nanostructures, has emerged as a powerful tool for dramatically improving the performance of fluorescence-based biomedical applications. Allowing for lower autofluorescence and minimal photoinduced damage, the development of multifunctional and multiplexed MEF platforms in the near-infrared (NIR) windows is particularly desirable. Here, a low-cost fabrication method based on nanosphere lithography is applied to produce tunable three-dimensional (3D) gold (Au) nanohole–disc arrays (Au-NHDAs). The arrays consist of nanoscale glass pillars atop nanoholes in a Au thin film: the top surfaces of the pillars are Au-covered (effectively nanodiscs), and small Au nanoparticles (nanodots) are located on the sidewalls of the pillars. This 3D hole–disc (and possibly nanodot) construct is critical to the properties of the device. The versatility of our approach is illustrated through the production of uniform and highly reproducible Au-NHDAs with controlled structural properties and tunable optical features in the NIR windows. Au-NHDAs allow for a very large NIR fluorescence enhancement (more than 400 times), which is attributed to the 3D plasmonic structure of the arrays that allows strong surface plasmon polariton and localized surface plasmon resonance coupling through glass nanogaps. By considering arrays with the same resonance peak and the same nanodisc separation distance, we show that the enhancement factor varies with nanodisc diameter. Using computational electromagnetic modeling, the electric field enhancement at 790 nm was calculated to provide insights into excitation enhancement, which occurs due to an increase in the intensity of the electric field. Fluorescence lifetime measurements indicate that the total fluorescence enhancement may depend on controlling excitation enhancement and therefore the array morphology. Our findings provide important in
Song W, Liu X, Wu B, et al., 2019, Sn@C evolution from yolk-shell to core-shell in carbon nanofibers with suppressed degradation of lithium storage, Energy Storage Materials, Vol: 18, Pages: 229-237, ISSN: 2405-8297
Metallic Sn has high conductivity and high theoretical capacity for lithium storage but it suffers from severe volume change in lithiation/delithiation leading to capacity fade. Yolk-shell and core-shell Sn@C spheres interconnected by carbon nanofibers were synthesized by thermal vapor and thermal melting of electrospun nanofibers to improve the cycling stability. Sn particles in yolk-shell spheres undergo dynamic structure evolution during thermal melting to form core-shell spheres. The core-shell spheres linked along the carbon nanofibers show outstanding performance and are better than the yolk-shell system for lithium storage, with a high capacity retention of 91.8% after 1000 cycles at 1 A g-1. The superior structure of core-shell spheres interconnected by carbon nanofibers has facile electron conductivity and short lithium ion diffusion pathways through the carbon nanofibers and shells, and re-develops Sn@C structures with Sn clusters embedded into carbon matrix during electrochemical cycling, enabling the high performance.
Theodorou I, Ruenraroengsak P, Carter D, et al., 2019, Towards multiplexed near-infrared cellular imaging using gold nanostar arrays with tunable fluorescence enhancement, Nanoscale, Vol: 11, Pages: 2079-2088, ISSN: 2040-3364
Sensitive detection of disease biomarkers expressed by human cells is critical to the development of novel diagnostic and therapeutic methods. Here we report that plasmonic arrays based on gold nanostar (AuNS) monolayers enable up to 19-fold fluorescence enhancement for cellular imaging in the near-infrared (NIR) biological window, allowing the application of low quantum yield fluorophores for sensitive cellular imaging. The high fluorescence enhancement together with low autofluorescence interference in this wavelength range enable higher signal-to-noise ratio compared to other diagnostic modalities. Using AuNSs of different geometries and therefore controllable electric field enhancement, cellular imaging with tunable enhancement factors is achieved, which may be useful for the development of multicolour and multiplexed platforms for a panel of biomarkers, allowing to distinguish different subcell populations at the single cell level. Finally, the uptake of AuNSs within HeLa cells and their high biocompatibility, pave the way for novel high-performance in vitro and in vivo diagnostic platforms.
Jiang Q, Ji C, Riley DJ, et al., 2019, Boosting the efficiency of photoelectrolysis by the addition of non-noble plasmonic metals: Al & Cu, Nanomaterials, Vol: 9, ISSN: 2079-4991
Solar water splitting by semiconductor based photoanodes and photocathodes is one of the most promising strategies to convert solar energy to chemical energy to meet the high demand for energy consumption in modern society. However, the state-of-the-art efficiency is too low to fulfill the demand. To overcome this challenge and thus enable the industrial realization of a solar water splitting device, different approaches have been taken to enhance the overall device efficiency, one of which is the incorporation of plasmonic nanostructures. Photoanodes and photocathodes coupled to the optimized plasmonic nanostructures, matching the absorption wavelength of the semiconductors, can exhibit a significantly increased efficiency. So far, gold and silver have been extensively explored to plasmonically enhance water splitting efficiency, with disadvantages of high cost and low enhancement. Instead, non-noble plasmonic metals such as aluminum and copper, are earth-abundant and low cost. In this article, we review their potentials in photoelectrolysis, towards scalable applications.
Fothergill S, Joyce C, Xie F, 2018, Metal enhanced fluorescence biosensing: from ultra-violet towards second near-infrared window, Nanoscale, Vol: 10, Pages: 20914-20929, ISSN: 2040-3364
To increase disease survival rates, there is a vital need for diagnosis at very preliminary stages. Then, low concentrations of biomarkers are present which must be effectively detected and quantified for reliable diagnosis. Fluorescent biosensing is commonly enabled through the labelling of these biomarkers with nanostructures and fluorophores. Metal Enhanced Fluorescence (MEF) is a phenomenon whereby the intensity of a fluorescent biosensor signal can be considerably enhanced by placing a metallic nanostructure and fluorophore in close proximity. Importantly, this allows for an even lower detection limit and thus earlier diagnosis. In recent years, extraordinary efforts have been made in the understanding of how the chemical and physical properties of nanomaterials may be exploited advantageously. Via precise nanoscale engineering, it is possible to optimize the optical properties of plasmonic nanomaterials, which now need to be refined and applied in diagnostics. Through MEF, the intensity of this signal can be related in direct proportion to analyte concentration, allowing for diagnosis of disease at an earlier stage than previously. This review paper outlines the potential and recent progress of applied MEF biosensors, highlighting their substantial clinical potential. MEF biosensors are presented both upon assay-based platforms and in solution, with comments on the various metallic nanoparticle morphologies available. This is explored across various emission wavelengths from ultra-violet to the second near infrared window (NIR-II), emphasising their wide applicability. Further to this, the importance of near infrared (NIR-I and NIR-II) biosensing is made clear as it allows for higher penetration in biological media. Finally, by developing multiplexing techniques, multiple and simultaneous analyses of analytes can be achieved. Through the incorporation of metal enhanced fluorescence into biosensing, it will be possible to diagnose disease more rapidly and more
Theodorou I, Jiang Q, Malms L, et al., 2018, Fluorescence enhancement from single gold nanostars: towards ultra-bright emission in the first and second near-infrared biological windows, Nanoscale, Vol: 10, Pages: 15854-15864, ISSN: 2040-3364
Gold nanostars (AuNSs) are promising agents for the development of high-performance diagnostic devices, by enabling metal enhanced fluorescence (MEF) in the physiological near-infrared (NIR) and second near-infrared (NIR-II) windows. The local electric field near their sharp tips and between their branches can be enhanced by several orders of magnitude, holding great promise for large fluorescence enhancements from single AuNS particles, rather than relying on interparticle coupling in nanoparticle substrates. Here, guided by electric field simulations, two different types of AuNSs with controlled morphologies and plasmonic responses in the NIR and NIR-II regions are used to investigate the mechanism of MEF from colloidal AuNSs. Fluorophore conjugation to AuNSs allows significant fluorescence enhancement of up to 30 times in the NIR window, and up to 4-fold enhancement in the NIR-II region. Together with other inherent advantages of AuNSs, including their multispike morphology offering easy access to cell membranes and their large surface area providing flexible multifunctionality, AuNS are promising for the development of in vivo imaging applications. Using time-resolved fluorescence measurements to deconvolute semi-quantitatively excitation enhancement from emission enhancement, we show that a combination of enhanced excitation and an increased radiative decay rate, both contribute to the observed large enhancement. In accordance to our electric field modelling, however, excitation enhancement is the component that varies most with particle morphology. These findings provide important insights into the mechanism of MEF from AuNSs, and can be used to further guide particle design for high contrast enhancement, enabling the development of MEF biodetection technologies.
Qin H, Wu D, Sathian J, et al., 2018, Tuning the upconversion photoluminescence lifetimes of NaYF4:Yb3+, Er3+ through lanthanide Gd3+ doping, Scientific Reports, Vol: 8, ISSN: 2045-2322
The multiplexing capacity of conventional fluorescence materials are significantly limited by spectral overlap and background interference, mainly due to their short-lived fluorescence lifetimes. Here, we adopt a novel Gd3+ doping strategy in NaYF4 host materials, realized tuning of upconversion photoluminescence (UCPL) lifetimes at selective emissions. Time-correlated single-photon counting (TCSPC), was applied to measure the photoluminescence lifetimes accurately. We demonstrated the large dynamic range of lifetimes of upconversion nanoparticles with good upconversion quantum yields, mainly owing to the dominance of high efficient energy transfer upconversion mechanism. The exceptional tunable properties of upconversion materials allow great potential for them to be utilized in biotechnology and life sciences.
Wang T, Centeno A, Darvill D, et al., 2018, Tuneable fluorescence enhancement over nanostructured ZnO arrays with controlled morphology, Physical Chemistry Chemical Physics, Vol: 21, Pages: 14828-14834, ISSN: 1463-9076
Zinc oxide (ZnO) nanorods (NRs) have been demonstrated as a promising platform for enhanced fluorescence-based sensing. It is, however, desirable to achieve a tuneable fluorescence enhancement with these platforms so that the fluorescence output can be adjusted based on the real need. Here we show that the fluorescence enhancement can be tuned by changing the diameter of the ZnO nanorods, simply controlled by potassium chloride (KCl) concentration during synthesis, using arrays of previously developed aligned NRs (a.k.a. aligned NR forests) and nanoflowers (NFs). Combining the experimental results obtained from ZnO nanostructures with controlled morphology and computer-aided verification, we show that the fluorescence enhancement factor increases when ZnO NRs become thicker. The fluorescence enhancement factor of NF arrays is shown to have a much stronger dependency on the rod diameter than that of aligned NR arrays. We prove that the morphology of nanostructures, which can be controlled, can be an important factor for fluorescence enhancement. Our (i) effort towards understanding the structure–property relationships of ZnO nanostructured arrays and (ii) demonstration on tuneable fluorescence enhancement by nanostructure engineering can provide some guidance towards the rational design of future fluorescence amplification platforms potentially for bio-sensing.
Riley DJ, Song W, Xie F, et al., 2018, Co3O4 hollow nanospheres doped with ZnCo2O4 via thermal vapor mechanism for fast lithium storage., Energy Storage Materials, Vol: 14, Pages: 324-334, ISSN: 2405-8297
Binary metal oxides offer improved anode materials in lithium ion batteries owing to enhanced electrical conductivity but suffer from large volume expansion on lithiation. A novel route to hollow Co3O4 nanospheres doped with ZnCo2O4 is demonstrated that mitigates the expansion issue and shows excellent performance at high current densities. The synthetic route is based on the pyrolysis of binary metal-organic-frameworks (MOFs) with the controlled loss of zinc tuning the micro and nanostructure of the material through a thermal vapor mechanism. The optimal structures, that contain hollow Co3O4 spheres of ca. 50 nm diameter doped with ZnCo2O4, show a specific capacity of 890 mAh g−1 at a current rate of 0.1 A g−1 and show a similar specific capacity at 1 A g−1 after 120 cycles at high current densities. The kinetics of lithiation/delithiation changes from diffusion-controlled to a surface-controlled process by the nanosizing of the particles. The resultant faster ion diffusion and capacitive storage for lithium ions are responsible for the extraordinary high-rate performance of the hollow structures.
Rashid NN, Aziz UA, Aid SR, et al., 2018, Effect of stress on activation during the formation of np junction in co-implanted germanium, Pages: 1-3
Higher carrier mobility in germanium has made germanium as a favorable candidate to replace silicon as a device substrate for a high-performance device. Further optimization on fabrication process parameters in germanium involving ion-implantation and thermal annealing is important to form a highly activated np junction. Co-implantation technique has prompted interest due to its reported stress-induced activation; which may be due to the implementation of two atoms different in size. Combining with ultra-fast/high temperature of laser thermal annealing may promotes the improvement in activation and damage removal. This works focused on introducing stress to the germanium substrate through co-implantation of dopant ions, follows by laser thermal annealing to activate and remove the implanted damages. It is found that Raman shift of the annealed co-implanted sample can be observed with 0.2% increase in the strain value, when comparing to the single implanted sample. 12% improvement of sheet resistance can also be observed, which may be related due to the increase in stress.
Centeno A, Rahmah Aid S, Xie F, 2018, Infra-Red Plasmonic Sensors, Chemosensors, Vol: 6, ISSN: 2227-9040
Plasmonic sensors exploiting the localized surface plasmon resonance (LSPR) of noble metal nanoparticles are common in the visual spectrum. However, bio-sensors near the infra-red (NIR) windows (600–900 nm and 1000–1400 nm) are of interest, as in these regions the absorption coefficients of water, melanin deoxyglobin, and hemoglobin are all low. The first part of this paper reviews the work that has been undertaken using gold (Au) and silver (Ag) particles in metal enhanced fluorescence (MEF) in the NIR. Despite this success, there are limitations, as there is only a narrow band in the visual and NIR where losses are low for traditional plasmonic materials. Further, noble metals are not compatible with standard silicon manufacturing processes, making it challenging to produce on-chip integrated plasmonic sensors with Au or Ag. Therefore, it is desirable to use different materials for plasmonic chemical and biological sensing, that are foundry-compatible with silicon (Si) and germanium (Ge). One material that has received significant attention is highly-doped Ge, which starts to exhibit metallic properties at a wavelength as short as 6 μm. This is discussed in the second part of the paper and the results of recent analysis are included.
Rashid NN, Aziz UA, Aid SR, et al., 2018, Effect of Stress on Activation during the Formation of np Junction in Co-Implanted Germanium, 18th International Workshop on Junction Technology (IWJT), Publisher: IEEE, Pages: 21-23
Centeno A, Aid SRB, Xie F, 2017, Infra-Red Plasmonic Sensors
<jats:p>Plasmonic sensors exploiting the Localized Surface Plasmon Resonance (LSPR) of noble metal nanoparticles are common in the visual spectrum. However, for bio-sensors the near infra-red (NIR) windows (600 nm &ndash; 900 nm and 1000 nm -1400 nm) are of interest, as it is a region where the absorption coefficient of water, melaninm deoxy- and hemoglobin are all low. The first part of this paper reviews the work that has been undertaken on using gold (Au) and silver (Ag) particles in Metal Enhanced Fluorescence (MEF) in the NIR. Despite this success there are limitations, as there is only a narrow band in the visual and NIR where losses are low for traditional plasmonic materials. Further, noble metals are not compatible with standard silicon manufacturing processes, making it challenging to produce on-chip integrated plasmonic sensors with Au or Ag. Therefore, it is desirable to use different materials for plasmonic chemical and biological sensing, that are foundry-compatible with silicon (Si) and germanium (Ge). One material that has received significant attention is highly doped Ge which starts to exhibit metallic properties at a wavelength as short as 6 &mu;m. This is discussed in the second part of the paper and the results of recent analysis are included.&nbsp;</jats:p>
Jawad ZAR, Theodorou I, Jiao LR, et al., 2017, Highly Sensitive Plasmonic Detection of the Pancreatic Cancer Biomarker CA 19-9, Scientific Reports, Vol: 7, ISSN: 2045-2322
Plasmonic gold (Au) nanotriangular arrays, functionalized with a near infrared (NIR) fuorophoreconjugatedimmunoassay to Carbohydrate Antigen 19-9 (CA 19-9), a pancreatic cancer biomarker,produce optically tunable substrates with two orders of magnitude fuorescence enhancement.Through nanoscale morphological control, the sensitivities of the plasmonic nanotriangular arraysare controllable, paving the way of such optical platforms for multiplexing. Here, we report a limit ofdetection (LOD) of 7.7×10−7 U.mL−1 for CA 19–9 by using such tunable Au nanotriangular arrays, agreat improvement compared to commercially available CA 19–9 immunoassays. The linear dynamicrange was from 1×10−6 U.mL−1 to 1 U.mL−1, i.e. up to six orders of magnitude. Moreover, highspecifcity was demonstrated, together with successful validation in serum samples. Their superiortunable sensitivity, along with eforts to combine CA 19–9 with other biomarkers for improved accuracy,open up the possibility for multiplexed NIR-fuorescence enhancement microarrays, for early cancerdiagnosis and therapeutic monitoring.
Song W, Brugge R, Theodorou IG, et al., 2017, Enhancing Distorted Metal Organic Framework Derived ZnO as Anode Material for Lithium Storage by the Addition of Ag2S Quantum Dots., ACS Applied Materials and Interfaces, Vol: 9, Pages: 37823-37831, ISSN: 1944-8244
The lithium storage properties of the distorted metal-organic framework (MOF) derived nanosized ZnO@C are significantly improved by the introduction of Ag2S quantum dots (QDs) during the processing of the material. In the thermal treatment, the Ag2S QDs react to produce Ag nanoparticles and ZnS. The metal nanoparticles act to shorten electron pathways and improve the connectivity of the matrix and the partial sulfidation of the ZnO surface improves the cycling stability of the material. The electrochemical properties of ZnO@C, Ag2S QDs treated ZnO@C and the amorphous carbon in ZnO@C have been compared. The small weight ratio of Ag2S QDs to ZnO@C at 1:180 shows the best performance in lithium storage. The exhibited specific capacities are improved and retained remarkably in the cycling at high current rates. At low current densi-ties (200 mA g-1) treatment of ZnO@C with Ag2S QDs results in a 38% increase in the specific capacity.
Liu L, Xie F, Meng X, et al., 2017, Environmentally benign nanomaterial synthesis mediated by culture broths, Biocatalysis and Nanotechnology, Editors: Grunwald, Publisher: Pan Stanford Publishing Pte. Ltd, Pages: 89-120, ISBN: 9781351767552
Theodorou I, Jawad Z, Jiang Q, et al., 2017, Gold Nanostar Substrates for Metal Enhanced Fluorescence through the First and Second Near-Infrared Windows, Chemistry of Materials, Vol: 29, Pages: 6916-6926, ISSN: 1520-5002
Gold nanostars (AuNSs) are receiving increasing attention for their potential applications in bionanotechnology because of their unique optical properties related to their complex branched morphology. Their sharp features allow strong localized surface plasmon resonances, tunable in the near-infrared (NIR) region, and large enhancements of local electromagnetic fields. Here, the application of AuNSs in metal-enhanced fluorescence (MEF) in the NIR and second NIR (NIR-II) biological windows is explored for the first time. NIR/NIR-II fluorophores are incorporated onto monolayers of AuNSs with tunable plasmonic responses. Over 320-fold fluorescence enhancement is achieved in the NIR, confirming that AuNS substrates are promising NIR-MEF platforms for the development of ultrasensitive biosensing applications. Using fluorescence lifetime measurements to semiquantitatively deconvolute the excitation enhancement from emission enhancement, as well as modeling to simulate the electric field enhancement, we show that a combination of enhanced excitation and an increased radiative decay rate, accompanied by an increase in the quantum yield, contribute to the observed large enhancement. AuNSs with different morphological features exhibit significantly different excitation enhancements, indicating the important role of the particle morphology on the magnitude of electromagnetic field enhancement and the resulting enhancement factor. Importantly, enhancement factors of up to 50-fold are also achieved in the NIR-II region, suggesting that this system holds promise for the future development of bright probes for NIR/NIR-II biosensing and bioimaging.
Rashid NN, Aziz UA, Aid SR, et al., 2017, Co-Implantation Germanium with Laser Thermal Annealing for the Formation of np Junction, 17th International Workshop on Junction Technology (IWJT), Publisher: IEEE, Pages: 91-93
Qin H, Shamso A, Centeno A, et al., 2017, Enhancing the upconversion photoluminescence of hexagonal phase NaYF4:Yb3+, Er3+ nanoparticles by mesoporous gold films, Physical Chemistry Chemical Physics, Vol: 19, Pages: 19159-19167, ISSN: 1463-9076
Efficient enhancement of photoluminescence in rare-earth activated upconversion materials is of great significance for their practical applications in various fields. In this work{,} three-dimensional mesoporous gold films were fabricated by a low-cost and facile dealloying approach to improve the upconversion photoluminescence efficiency. The mesoporous Au films exhibit good chemical stability{,} large-area uniformity and abundant distribution of porous nanospaces. Varying the time of the dealloying process leads to modification of pore size distribution{,} surface roughness and residual Ag content{,} resulting in effective tuning the wavelength of the broadband localized surface plasmon resonance (LSPR). Enhancement factors were identified to be a function of the dealloying time. With the optimized upconversion photoluminescence enhancement a 41-fold increase was achieved with the mesoporous gold substrate which had been dealloyed for 8 days. These results pave the way to overcome the limitation of poor upconversion efficiency for widespread practical applications in life sciences and energy applications.
Aziz UA, Rashid NNM, Aid SR, et al., 2017, Electrical and Structural Analysis on the Formation of n-type Junction in Germanium, 5th International Conference on Nanomaterials and Materials Engineering (ICNME), Publisher: IOP PUBLISHING LTD, ISSN: 1757-8981
Xie F, Deng W, Goldys E, 2017, Compatibility of Metal –Induced Fluorescence Enhancement with Applications in Analytical Chemistry and Biosensing, Surface Plasmon Enhanced, Coupled and Controlled Fluorescence, Editors: Geddes, Publisher: Wiley, Pages: 13-36, ISBN: 978-1-118-02793-6
Riley DJ, Song W, Lischner, et al., 2017, Tuning the Double Layer of Graphene Oxide through Phosphorus Doping for Enhanced Supercapacitance, ACS Energy Letters, Vol: 2, Pages: 1144-1149, ISSN: 2380-8195
The electrochemical double layer plays a fundamental role in energy storage applications. Control of the distribution of ions in the double layer at the atomistic scale offers routes to enhanced material functionality and device performance. Here we demonstrate how the addition of an element from the third row of the periodic table, phosphorus, to graphene oxide increases the measured capacitance and present density functional theory calculations that relate the enhanced charge storage to structural changes of the electrochemical double layer. Our results point to how rational design of materials at the atomistic scale can lead to improvements in their performance for energy storage.
Pang J, Theodorou I, Centeno A, et al., 2016, Gold nanodisc arrays as near infrared metal-enhanced fluorescence platforms with tuneable enhancement factors, Journal of Materials Chemistry C, Vol: 5, Pages: 917-925, ISSN: 2050-7534
Metal enhanced fluorescence (MEF) is a physical effect through which the near-field interaction of fluorophores with metallic nanoparticles can lead to large fluorescence enhancement. MEF can be exploited in many fluorescence-based biomedical applications, with potentially significant improvement in detection sensitivity and contrast enhancement. Offering lower autofluorescence and minimal photoinduced damage, the development of effective and multifunctional MEF platforms in the near-infrared (NIR) region, is particularly desirable. In this work, the enhancement of NIR fluorescence caused by interaction with regular arrays of cylindrical gold (Au) nanoparticles (nanodiscs), fabricated through nanosphere lithography, is reported. Significant MEF of up to 235 times is obtained, with tuneable enhancement factors. The effect of array structure on fluorescence enhancement is investigated by semi-quantitatively de-convoluting excitation enhancement from emission enhancement, and modelling the local electric field enhancement. By considering arrays of Au nanodiscs with the same extinction maximum, it is shown that the excitation enhancement, due to increased electric field, is not significantly different for the particle sizes and separation distances considered. Rather, it is seen that the emission from the fluorophore is strongly enhanced, and is dependent on the topography, in particular particle size. The results show that the structural characteristics of Au nanodisc arrays can be manipulated to tune their enhancement factor, and hence their sensitivity.
Theodorou IG, Jawad Z, Qin H, et al., 2016, Significant metal enhanced fluorescence of Ag2S quantum dots in the second near-infrared window, Nanoscale, Vol: 8, Pages: 12869-12873, ISSN: 2040-3372
The amplification of light in NIR-II from Ag2S QDs via metal enhanced fluorescence (MEF) is reported for the first time. Significant fluorescence enhancement of over 100 times for Ag2S QDs deposited on Au-nanostructured arrays, paves the way for novel sensing and imaging applications based on Ag2S QDs, with improved detection sensitivity and contrast enhancement.
Song W, Chen J, Xiaobo J, et al., 2016, Dandelion-shape TiO2/Multi-layer Graphene Composed of TiO2(B) Fibrils and Anatase TiO2 Pappi Utilizing Triphase Boundaries for Lithium Storage, Journal of Materials Chemistry A, Vol: 4, Pages: 8762-8768, ISSN: 2050-7496
Three‐dimensional dandelion‐shape TiO2/Multi‐layer graphene compound (TiO2/MLG) composed of TiO2(B) fibrils andanatase pappi structures has been synthesized as potential anode material for Li storage. Electronmicroscopy indicatesthat the composite contains triphase boundaries between anatase, TiO2(B) and graphene, which are responsible for theenhancement of energy storage and the decrease of electrode polarization. Cyclic voltammetric investigations indicatethat both Li+ insertion and pseudocapacitance contribute to charge storage. Ultrahigh specific capacities of 243 and 182mAh g‐1 have been obtained at 0.1 and 1 A g‐1, respectively. Moreover, the excellent capacity retention can reach 99.6%after 100 cycles with almost 100% coulombic efficiency at 0.1 A g‐1. The importance of the triphase boundary in enhancingthe storage of charge and transport of Li+ is demonstrated.
Zhang X, Wu X, Centeno A, et al., 2016, Significant broadband photocurrent enhancement by Au-CZTS core-shell nanostructured photocathodes, Scientific Reports, Vol: 6, ISSN: 2045-2322
Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.
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