ORCID Profile
0000-0001-9484-0868
Current Organisations
Monash University
,
Universitat Autònoma de Barcelona (UAB)
,
Universitat Autònoma de Barcelona
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Publisher: The Chemical Society of Japan
Date: 15-12-2019
Publisher: Thomas Telford Ltd.
Date: 08-2021
Abstract: Carbon- and oxygen-doped hexagonal boron nitrides (BCNOs) with good chemical stability and photoresponsiveness to visible light are found to be promising metal-free catalysts for degradation of Rhodamine B (RhB). By doping with heteroatoms of carbon and oxygen, insulating hexagonal boron nitride was transformed into semiconducting BCNO. The BCNO photocatalyst presents photodegradation performance towards RhB, with degradation rates up to 1.39 h −1 (0.05 wt% catalyst loading). The active species involved in the photoreaction were demonstrated to be superoxide anion radical (˙O 2 − ) and holes (h + ), as opposed to ˙OH in the most studied titanium dioxide. The stability of BCNO in highly acidic environments was exploited for catalyst regeneration, as is necessary after long-term use and poisoning. This work demonstrates that BCNO is a promising low-cost and metal-free photocatalyst for environmental pollution remediation.
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.JCIS.2013.11.072
Abstract: Enhanced photocatalytic degradation of methylene blue (MB) using graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) catalyst films has been demonstrated in this present work. The g-C3N4/TiO2 composites were prepared by directly heating the mixture of melamine and pre-synthesized TiO2 nanoparticles in Ar gas flow. The g-C3N4 contents in the g-C3N4/TiO2 composites were varied as 0, 20, 50 and 70 wt%. It was found that the visible-light-induced photocatalytic degradation of MB was remarkably increased upon coupling TiO2 with g-C3N4 and the best degradation performance of ~70% was obtained from 50 wt% g-C3N4 loading content. Results from UV-vis absorption study, Electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggest that the improved photoactivity is due to a decrease in band gap energy, an increased light absorption in visible light region and possibly an enhanced electron-hole separation efficiency as a result of effective interfacial electron transfer between TiO2 and g-C3N4 of the g-C3N4/TiO2 composite film. Based on the obtained results, the possible MB degradation mechanism is ascribed mainly to the generation of active species induced by the photogenerated electrons.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4CP05722H
Abstract: N719 and D149, were used as sensitizers of Rutile TiO 2 -based DSCs, with maximum η of 5.6% and 5.8% achieved, respectively.
Publisher: MDPI AG
Date: 09-01-2023
Abstract: Dye-sensitized solar cells (DSCs) remain an interesting photovoltaic concept, although recent times have seen their envisioned broad-scale applications being replaced with more niche ones. Nevertheless, as a key component of DSCs, titanium(IV) oxide (TiO2) must be produced in a large volume, low cost, and highly reproducible manner. Degussa P25 remains a benchmark TiO2 product, addressing the first two of the above points very well. Post-treatment processes that may also be carried out on a large scale give some hope to addressing the reproducibility issue. This paper builds on our previous works wherein mixed-phase P25 (anatase + rutile + amorphous TiO2) was converted into an amorphous free form by selectively dissolving and recrystallizing the amorphous component. Here we investigated the performance of metal-free organic dye (D149)-based DSCs with three different TiO2 films: (1) as-received P25 (TiO2-P25), (2) amorphous-free P25 (TiO2-HP25), and (3) anatase nanoparticles obtained from Dyesol (TiO2-DSL). DSCs based on TiO2-HP25 showed comparable performance (5.8 ± 0.2% PCE) to DSCs based on the TiO2-DSL (5.8 ± 0.4% PCE) and substantially higher than for devices based on the as-obtained P25 nanoparticles (3.9 ± 0.4% PCE). The enhancement resulting from the post-processing of P25 derives from simultaneous increases in photo-current density (Jsc), open-circuit voltage (VOC), and the fill factor (FF), due to enhancing the dye-loading capability and the charge-transport efficiency (suppressing the electron recombination) as a result of the removal of amorphous barriers and associated defect states. This is in line with enhancing DSC performance based on the organometallic N719 dye we reported previously. However, the photoanode material based on abundant P25 TiO2 sensitized with high-extinction-coefficient organic D149 dye can be adopted as a cost-effective DSC as an alternative to relatively high-cost DSCs based on the commercial anatase TiO2 sensitized with organometallic N719 dye.
Publisher: American Chemical Society (ACS)
Date: 24-11-2015
Abstract: This study reports evidence of dispersive transport in planar PbS colloidal quantum dot heterojunction-based devices as well as the effect of incorporating a MoO3 hole selective layer on the charge extraction behavior. Steady state and transient characterization techniques are employed to determine the complex recombination processes involved in such devices. The addition of a selective contact drastically improves the device efficiency up to 3.15% (especially due to increased photocurrent and decreased series resistance) and extends the overall charge lifetime by suppressing the main first-order recombination pathway observed in device without MoO3. The lifetime and mobility calculated for our sulfur-rich PbS-based devices are similar to previously reported values in lead-rich quantum dots-based solar cells. Nevertheless, strong Shockley-Read-Hall mechanisms appear to keep restricting charge transport, as the equilibrium voltage takes more than 1 ms to be established.
Publisher: Elsevier BV
Date: 03-2019
Publisher: Wiley
Date: 24-09-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4NR07006B
Abstract: In-depth structural study of methanol treated S-rich PbS quantum dots undergoing hydroxylation under atmospheric conditions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7CC07559F
Abstract: P25 is one of the most widely used forms of titanium( iv ) oxide (TiO 2 ), routinely utilised in dye-sensitised solar cells (DSCs), where it is often employed as a control, in spite of its poorly defined nature and the typically low device efficiency.
Publisher: Informa UK Limited
Date: 15-05-2017
Publisher: MDPI AG
Date: 30-12-2021
DOI: 10.3390/S22010254
Abstract: Turbidity is one of the primary metrics to determine water quality in terms of health and environmental concerns, however analysis typically takes place in centralized facilities, with s les periodically collected and transported there. Large scale autonomous deployments (WSNs) are impeded by both initial and per measurement costs. In this study we employ a Paired Emitter-Detector Diode (PEDD) technique to quantitatively measure turbidity using analytical grade calibration standards. Our PEDD approach compares favorably against more conventional photodiode-LED arrangements in terms of spectral sensitivity, cost, power use, sensitivity, limit of detection, and physical arrangement as per the ISO 7027 turbidity sensing standard. The findings show that the PEDD technique was superior in all aforementioned aspects. It is therefore more ideal for low-cost, low-power, IoT deployed sensors. The significance of these findings can lead to environmental deployments that greatly lower the device and per-measurement costs.
Publisher: Elsevier BV
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 04-09-2017
DOI: 10.1038/S41598-017-09911-W
Abstract: Hierarchically structured aggregates, consisting of TiO 2 nanoparticles were produced via one-step solvothermal syntheses with a mixed solvent system containing both acetic acid and ethanol. Two of the resulting structures, one ~700 nm and the other ~300 nm in diameter, were found to be comprised of 8.5 nm and 10.5 nm anatase crystals, and possess specific surface areas of 138 and 106 m 2 g −1 respectively. These particles were incorporated into Dye-sensitized Solar Cells (DSCs) as high surface area scattering layers, along with a layer of a transparent material. Solar-to-electric conversion efficiencies (PCE) of 9.1% and 8.2% were recorded using these aggregated particles as compared to those of commonly used large particles scattering layer 7.4%.
Publisher: American Chemical Society (ACS)
Date: 11-06-2013
DOI: 10.1021/JZ401050U
Abstract: Photon upconversion (UC) by triplet-triplet annihilation (TTA-UC) is employed in order to enhance the response of solar cells to sub-bandgap light. Here, we present the first report of an integrated photovoltaic device, combining a dye-sensitized solar cell (DSC) and TTA-UC system. The integrated device displays enhanced current under sub-bandgap illumination, resulting in a figure of merit (FoM) under low concentration (3 suns), which is competitive with the best values recorded to date for nonintegrated systems. Thus, we demonstrate both the compatibility of DSC and TTA-UC and a viable method for device integration.
Publisher: Oxford University Press (OUP)
Date: 14-02-2019
DOI: 10.1002/STEM.2966
Abstract: When considering the clinical applications of autologous cell replacement therapy of human induced pluripotent stem cells (iPSC)-derived cells, there is a clear need to better understand what the immune response will be before we embark on extensive clinical trials to treat or model human disease. We performed a detailed assessment comparing human fibroblast cell lines (termed F1) reprogrammed into human iPSC and subsequently differentiated back to fibroblast cells (termed F2) or other human iPSC-derived cells including neural stem cells (NSC) made from either retroviral, episomal, or synthetic mRNA cell reprogramming methods. Global proteomic analysis reveals the main differences in signal transduction and immune cell protein expression between F1 and F2 cells, implicating wild type (WT) toll like receptor protein 3 (TLR3). Furthermore, global methylome analysis identified an isoform of the human TLR3 gene that is not epigenetically reset correctly upon differentiation to F2 cells resulting in a hypomethylated transcription start site in the TLR3 isoform promoter and overexpression in most human iPSC-derived cells not seen in normal human tissue. The human TLR3 isoform in human iPSC-NSC functions to suppress NF-KB p65 signaling pathway in response to virus (Poly IC), suggesting suppressed immunity of iPSC-derived cells to viral infection. The sustained WT TLR3 and TLR3 isoform overexpression is central to understanding the altered immunogenicity of human iPSC-derived cells calling for screening of human iPSC-derived cells for TLR3 expression levels before applications. Stem Cells 2019 :476–488
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Elsevier BV
Date: 2022
Publisher: MDPI AG
Date: 16-02-2022
DOI: 10.3390/S22041526
Abstract: This work explores the effects of embedded software-driven measurements on a sensory target when using a LED as a photodetector. Water turbidity is used as the sensory target in this study to explore these effects using a practical and important water quality parameter. Impacts on turbidity measurements are examined by adopting the Paired Emitter Detector Diode (PEDD) capacitive discharge technique and comparing common embedded software/firmware implementations. The findings show that the chosen software method can (a) affect the detection performance by up to 67%, (b) result in a variable s ling frequency eriod, and (c) lead to an disagreement of the photo capacitance by up to 23%. Optimized code is offered to correct for these issues and its effectiveness is shown through comparative analyses, with the disagreement reduced significantly from 23% to 0.18%. Overall, this work demonstrates that the embedded software is a key and critical factor for PEDD capacitive discharge measurements and must be considered carefully for future measurements in sensor related studies.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4TA06656A
Abstract: A new photoanode architecture for cold isostatic pressing (CIP), with microstructured TiO 2 sea-urchin-like assemblies, composed of high aspect-ratio single-crystal nanoribbons deposited onto P25, was rationally designed for highly durable, flexible dye-sensitized solar cells.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TA15444K
Abstract: Highly connected hierarchical textured TiO 2 spheres, composed of high aspect-ratio nanosheets, gave high conversion efficiency in dye-sensitized solar cells.
Publisher: Springer Science and Business Media LLC
Date: 29-08-2014
DOI: 10.1038/SREP05769
Publisher: Elsevier BV
Date: 2015
Publisher: MDPI AG
Date: 08-03-2019
DOI: 10.3390/APP9050979
Abstract: Dye-sensitised solar cells continue to be a promising photovoltaic technology for indoor and outdoor applications, with increased interest in power window applications integrated into buildings. This results from properties not seen in other, more established solar technologies, such as the range of available colours, partial transparency and good performance under low light intensities or in partial shade. In spite of the attractiveness of this application and the commercial availability of suitable non-scattering TiO2 materials, the vast majority of new TiO2 materials being developed and reported in the literature are dried prior to being made into a paste and subsequently into photoanode films. Here, we make a detailed side-by-side comparison of different paste-forming techniques, with one yielding scattering films, and the other yielding non-scattering films. Devices utilising the organic dye D149 showed comparable performance using both approaches (6.9% photovoltaic conversion efficiency (PCE) with drying versus 6.4% PCE without drying), while the difference was slightly more marked with the dye N719 (7.7% PCE versus 6.8% PCE), suggesting that the trade-off in light harvesting required for power windows may be acceptably small. We also discuss ways by which these differences may be further decreased.
Publisher: MDPI AG
Date: 04-04-2014
DOI: 10.3390/JCM3020373
Publisher: American Chemical Society (ACS)
Date: 26-05-2015
No related grants have been discovered for Iñaki Alvarez.