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Noble metal decoration of wideband gap semiconductors enables the excitation of surface plasmons in the visible range that upon relaxation generate hot carriers used for catalysis. However, this strategy leads to photocatalytic conversion efficiencies that are still low. Here, a light-trapping scheme is used to amplify the light-harvesting efficiency of the TiO2 semiconductor beyond the UV region by coupling a 2D-photonic crystal to Au decorated titania. This approach is easily scalable using soft nanoimprinting lithography to prepare Au/TiO2 2D-photonic photocatalysts. In a first process, gold nanoparticles (Au NPs) are in situ infiltrated in the superficial 50 nm of a mesoporous titania (mTiO2) scaffold patterned with the photonic structure, while in a second one 2D-photonic crystals with a homogeneous volume distribution of the Au colloids are achieved. The dependence of the optical properties of the photonic crystals on the lattice parameter, geometry, and metal loading is presented through extinction measurements and analyzed through simulations. The improved photocatalytic performance of the substrates is tested for hydrogen production where a maximum of 8.5 mmol gcat−1 h−1 of H2 is recorded and attributed to photonic–plasmonic effects. These results may open new avenues in solar harvesting for hydrogen production using photonic crystals as photocatalysts.

This project analyzes the effect that promotions can have on sales in the fast-moving consumer goods industry. To answer this question, first a baseline for the sales time series is calcula- ted. Different methods are compared to find the one best suited to the working dataset. Then, using the type of promotion, the computed incremental volume, and information about the un- derlying product and its category, promotions are grouped in clusters with the goal of finding commonalities and trends. The project’s findings demonstrate that using a monthly average is the most precise way to de- termine the sales baseline. The findings also indicated that while there are no trends that are meaningful enough to be used to forecast the increase in sales from a promotion, the clusters de- veloped using the type of promotion and product segment as variables can be successfully used to evaluate the effectiveness of promotions, providing insight into which should be prioritised or otherwise avoided. The dataset is the project’s primary source of constraints, necessitating better data, but the con- sequences are clear: via thorough research, the underlying business dynamics may be better understood, leading to enhanced promotion planning and management, Aquest projecte analitza l’efecte que les promocions tenen sobre les vendes en el sector de gran consum. Per respondre aquesta pregunta, primer es calcula una línia de base per a la sèrie temporal referent a la quantitat de vendes. Es comparen diferents mètodes per trobar el més adequat per al conjunt de dades de treball. Llavors, utilitzant el tipus de promoció, el volum incremental calculat, i informació sobre el producte subjacent i la seva categoria, les promocions s’agrupen en clústers amb l’objectiu de trobar similituds i tendències. Les conclusions del projecte demostren que l’ús d’una mitjana mensual és la manera més precisa de determinar la línia de base de vendes. Les troballes també indiquen que mentre no hi ha tendències prou significatives per ser usades per predir l’augment de vendes d’una promoció, els clústers desenvolupats emprant el tipus de promoció i segment de producte com variables poden ser usats amb èxit per avaluar l’eficàcia de promocions, proporcionant una visió sobre quines haurien de ser prioritzades o evitades. El conjunt de dades és la principal font de restriccions del projecte, necessitant millors dades, però les implicacions són clares: a través d’una recerca exhaustiva, la dinàmica empresarial subjacent pot ser entesa, i contribuir a millorar la planificació i gestió de promocions

The intensive monitoring of water quality enforced by new wastewater regulations calls for the developing of fast and low-cost analytical technologies. Electrochemical sensors are poised to become alternative technologies for the sensitive analysis of environmentally relevant chemicals. A prerequisite for this evolution is engineering analyte-specific electrodes which are easily processed and can be mass-produced. This work studies different routes to prepare composites comprising a porous carbon matrix with Cu or Cu2O nanoparticles as electrodes to analyze chemical oxygen demand (COD) in wastewaters. The materials were prepared by physical mixing of the two components and one-pot chemical synthesis, characterizing their microstructure, porosity, nanoparticle distribution, and crystallinity. Then, their analytical performance was assessed by measuring glucose as a standard analyte and testing three real samples from a wastewater treatment plant. While all the materials performed well in the COD analysis, in excellent agreement with those obtained by the standard dichromate method, a one-pot synthesis approach stands out for its ease of production and analytical response. This one-step liquid processing is scalable and compatible with the industrial manufacturing of electrochemical sensors of planar configuration by screen-printing or microfabrication techniques.

Noble metal decoration of wideband gap semiconductors enables the excitation of surface plasmons in the visible range that upon relaxation generate hot carriers used for catalysis. However, this strategy leads to photocatalytic conversion efficiencies that are still low. Here, a light-trapping scheme is used to amplify the light-harvesting efficiency of the TiO2 semiconductor beyond the UV region by coupling a 2D-photonic crystal to Au decorated titania. This approach is easily scalable using soft nanoimprinting lithography to prepare Au/TiO2 2D-photonic photocatalysts. In a first process, gold nanoparticles (Au NPs) are in situ infiltrated in the superficial 50 nm of a mesoporous titania (mTiO2) scaffold patterned with the photonic structure, while in a second one 2D-photonic crystals with a homogeneous volume distribution of the Au colloids are achieved. The dependence of the optical properties of the photonic crystals on the lattice parameter, geometry, and metal loading is presented through extinction measurements and analyzed through simulations. The improved photocatalytic performance of the substrates is tested for hydrogen production where a maximum of 8.5 mmol gcat-1 h-1 of H2 is recorded and attributed to photonic–plasmonic effects. These results may open new avenues in solar harvesting for hydrogen production using photonic crystals as photocatalysts., Postprint (author's final draft)

Copper and copper oxide nanoparticles (NPs) are industrially important. In particular, Cu-based nanocatalysts find applicability in electrocatalysis and photocatalysis, profiting from the accessible oxidation states of copper and a band gap in the visible region of the Cu2O phase. However, in this case, the fast recombination of the charge carriers compromises the final photocatalytic efficiency. The combination of Cu2O with metals often results in higher and more stable photocatalytic efficiency. Here, the fabrication of noble metal NPs [Au, Ag, Pd, and Pt] and Cu2O heterostructures (HSs) by a microwave (MW)-assisted synthesis is presented. The selectivity of the MW technique with a fast two-step protocol enabled us to easily prepare these multicomponent nanoparticles in a short time (∼40 min). First, metal NPs (Au, Ag, or Pd) are synthesized through a MW-assisted polyol approach, and these NPs serve as nucleation seeds for cubic Cu2O wrapping. Other types of heterostructures were found when using smaller Pt NPs instead. Focusing on Au NPs as the core, we analyzed the effect of the gold to copper molar ratio on the shape yield of the nanocubes, reported their optic and plasmonic properties, and demonstrated the reproducibility and scalability of the synthetic routes. Here, we are providing a pioneering example of MW heating as a non-conventional energy source for a general chemical approach to attain a family of complex metal/metal oxide heterostructures.

The selection and comparative study is reported of calibration curves to quantify iron by a simple UV-Vis protocol based on the formation of iron (III) chloride complexes. The reliability of each calibration curve was evaluated using statistical and analytical parameters. The robustness of each calibration curve using superparamagnetic iron oxide nanoparticles (SPIONs) of different sizes and surface functionalization is demonstrated . We have also evaluated the effect of the particle coating and estimated the minimum time to ensure the full oxidation of iron (II) to (III) in sample solutions. Results from UV-Vis are comparable with those obtained from ICP-OES and from other spectroscopic techniques to quantify the iron. We advocate the proposed protocol as a simple and non-expensive route to determine accurately the iron content in colloidal and nanocomposite iron-based materials.

The fabrication of silver nanoparticles (Ag NPs) with different sizes by microwave (MW)-assisted synthesis is presented. The fast heating of the MW technique, combined with the possibility to thermally quench the reactions, enabled us to capture snapshots of nucleation and growth processes difficult to accomplish in other techniques. The Ag NPs were synthesized using poly(vinylpyrrolidone) (PVP) through a polyol approach. The effects of the reaction time, the reaction temperatures, and the silver precursor concentration were investigated. The influence of agitation, the PVP concentration, and the initial conditions of the silver precursor was also studied. It is found that at very short reaction times and at low temperatures, polyhedral plates are formed with sizes ca. 300 nm and large polydispersity. However, by increasing the time or the temperature, a size and shape refinement is observed resulting in 10 nm spherical NPs with low polydispersity. Mechanistic insights are provided based on the observations extracted from transmission electron microscopy (TEM) and ultraviolet−visible spectroscopy (UV−vis). A formation mechanism starting from kinetically favored silver polyhedral plates to thermodynamically favored spherical nanoparticles is proposed. Understanding these effects allowed us to control the particle size and the tuning of Ag NPs ondemand. Moreover, the reproducibility and scalability of the process and the long-term stability of the NPs in aqueous solutions are demonstrated. Finally, we provide a recommendation regarding the use of fresh PVP as a capping and stabilizing agent.

The fabrication of small anatase titanium dioxide (TiO2) nanoparticles (NPs) attached to larger anisotropic gold (Au) morphologies by a very fast and simple two-step microwave-assisted synthesis is presented. The TiO2/Au NPs are synthesized using polyvinylpyrrolidone (PVP) as reducing, capping and stabilizing agent through a polyol approach. To optimize the contact between the titania and the gold and facilitate electron transfer, the PVP is removed by calcination at mild temperatures. The nanocatalysts activity is then evaluated in the photocatalytic production of hydrogen from water/ethanol mixtures in gas-phase at ambient temperature. A maximum value of 5.3 mmol·g-1 cat·h-1 (7.4 mmol·g-1 TiO2 ·h-1) of hydrogen is recorded for the system with larger gold particles at an optimum calcination temperature of 450¿C. Herein we demonstrate that TiO2-based photocatalysts with high Au loading and large Au particle size (˜50 nm) NPs have photocatalytic activity., Postprint (published version)

The fabrication of small anatase titanium dioxide (TiO2) nanoparticles (NPs) attached to larger anisotropic gold (Au) morphologies by a very fast and simple two-step microwave-assisted synthesis is presented. The TiO2/Au NPs are synthesized using polyvinylpyrrolidone (PVP) as reducing, capping and stabilizing agent through a polyol approach. To optimize the contact between the titania and the gold and facilitate electron transfer, the PVP is removed by calcination at mild temperatures. The nanocatalysts activity is then evaluated in the photocatalytic production of hydrogen from water/ethanol mixtures in gas-phase at ambient temperature. A maximum value of 5.3 mmol·g−1cat⋅h−1 (7.4 mmol·g−1TiO2⋅h−1) of hydrogen is recorded for the system with larger gold particles at an optimum calcination temperature of 450°C. Herein we demonstrate that TiO2-based photocatalysts with high Au loading and large Au particle size (≈50 nm) NPs have photocatalytic activity.

La síntesi de nanopartícules multimaterial que presentin més d’una propietat funcional fent servir metodologies senzilles continua essent un gran desafiament. Aquí es presenta la fabricació ràpida i respectuosa amb el medi ambient de nanopartícules híbrides, combinació d’òxid de ferro i or en una sola nanopartícula, mitjançant una síntesi de poliol assistida per microones de dos passos. El sistema d’escalfament assistit per microones permet la fabricació de nanoestructures multicomponent i multifuncionals mitjançant la promoció d’un escalfament selectiu. Les nanopartícules multimaterial resultants presenten propietats magnètiques i plasmòniques, s’obtenen amb un alt control de la seva forma i evitant reactius tòxics i es poden destinar a noves aplicacions en biodetecció, imatge mèdica o teràpia. Aquests nanocompòsits consisteixen en nanotriangles d’or monodispersos d’uns 200 nm d’aresta amb un recobriment homogeni i uniforme de nanopartícules d’òxid de ferro superparamagnètiques de 14 nm. Els nanotriangles són fàcilment dispersables en aigua, mostren una forta resposta magnètica i presenten una banda de ressonància plasmònica localitzada a la regió de l’infraroig proper (800 nm). A més, aquestes partícules híbrides es poden autoassemblar a les interfícies líquid-aire. També es presenten un mètode per eliminar les nanopartícules d’òxid de ferro de la superfície dels nanocristalls d’or i algunes idees sobre els mecanismes de nucleació dels nanocristalls i el seu creixement.Paraules clau: Nanotriangles d’or, materials plasmònics, nanopartícules d’òxid de ferro, su, Simple approaches to synthesize multimaterial nanoparticles that exhibit more than one functional property remain a huge challenge. Here, the fabrication of hybrid nanoparticles combination of iron oxide and gold on a single particle by a simple, fast and environmentally-friendly two-step microwave-assisted polyol synthesis is presented. Microwave assisted heating allows the fabrication of multicomponent, multifunctional nanostructures by promoting selective heating at desired sites. The resulting complex nanoparticles have magnetic and plasmonic properties, and are obtained with high control of their shape and avoiding cytotoxic reactants, being able to use them for novel applications in bio-sensing, medical imaging, or therapeutics. These nanocomposites consist of monodisperse gold nanotriangles around 200 nm in size with a homogeneous and uniform coating of superparamagnetic iron oxide nanoparticles of 14 nm. These nanotriangles are readily dispersible in water, display a strong magnetic response and exhibit a localized surface plasmon resonance band in the near-infrared region (800 nm). Moreover, these hybrid particles can be easily self-assembled at the liquid–air interfaces. A method to remove the iron oxide nanoparticles from the gold nanocrystals surface and some insights on crystal nucleation and growth mechanisms are also provided.Keywords: Gold nanotriangles, plasmonic materials, iron oxide nanoparticles, superparamagnetism, microwave-assisted synthesis.