Resultados de investigación

The combination of instrumental techniques allows obtaining precise and reliable information about the reactions taking place at the electrode/solution interface. Although UV?Vis absorption spectroelectrochemistry (UV?Vis SEC) provides a molecular insight about the species involved in the electrode process, obtaining information about the redox state of the products generated in this process is not always accessible by this technique. In this sense, scanning electrochemical microscopy (SECM) has a clear advantage, since it provides additional information on the oxidation state of the intermediates/products. Therefore, the combination of these two techniques facilitates obtaining a more complete picture of the electrochemical reaction studied from two different points of view, but under exactly the same experimental conditions. In this work, the combination of UV?Vis SEC in parallel configuration and SECM is carried out for the first time. This new technique allows distinguishing between those species that are electrochemically active and, at the same time, exhibit changes in the UV?Vis absorption spectra during the electrochemical reaction. The new experimental setup is first validated using ferrocenemethanol as a standard probe, concomitantly obtaining spectroscopic and electrochemical information that accurately describes the oxidation process. Finally, the strength of this combined technique is demonstrated by studying the antioxidant activity of o-vanillin (o-HVa) in the presence of electrogenerated superoxide. The information extracted from the new UV?Vis SEC/SECM technique makes it possible to identify, beyond any doubt, not only the origin of the electrochemical signals recorded in the SECM tip but also to evaluate the antioxidant effect of o-HVa at different concentrations., Open Access funding provided thanks to the CRUE-CSIC agreement with American Chemical Society (ACS). The authors acknowledge Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033 and PID2020-113154RB-C21) and Ministerio de Ciencia, Innovación y Universidades (RED2018-102412-T) for the support of this work. J.V.P.-R. acknowledges Ministerio de Universidades and European Union-NextGenerationEU for his Maria Zambrano fellowship. S.H. thanks JCyL and European Social Fund for her predoctoral fellowship.

Raman signal enhancement is fundamental to develop different analytical tools for chemical analysis, interface reaction studies, or new materials characterization, among others. Thus, phenomena such as surface-enhanced Raman scattering (SERS) have been used for decades to increase the sensitivity of Raman spectroscopy, leading to a huge development of this field. Recently, an alternative method to SERS for the amplification of Raman signals has been reported. This method, known as electrochemical surface oxidation-enhanced Raman scattering (EC-SOERS), has been experimentally described. However, to date, it has not yet been fully understood. In this work, new experimental data that clarify the origin of the Raman enhancement in SOERS are provided. The use of a complete and unique set of combined spectroelectrochemistry techniques, including time-resolved operando UV?vis absorption, fluorescence, and Raman spectroelectrochemistry, reveals that such enhancement is related to the generation of dielectric or semiconductor nanocrystals on the surface of the electrode and that the interaction between the target molecule and the dielectric substrate is mediated by metal cations. According to these results, the interaction metal electrode?nanocrystal?metal cation?molecule is proposed as being responsible for the Raman enhancement in Ag and Cu substrates. Elucidation of the origin of the Raman enhancement will help to promote the rational design of SOERS substrates as an attractive alternative to the well-known SERS phenomenon., Open Access funding provided thanks to the CRUE-CSIC agreement with American Chemical Society (ACS). This work was funded by the Ministerio de Ciencia e Innovacio?n and Agencia Estatal de Investigacio?n (MCIN/AEI/10.13039/501100011033 and PID2020-113154RB-C21), Ministerio de Ciencia, Innovacio?n y Universidades (RED2022-134120-T). S.H. acknowledges Junta de Castilla y León and European Social Found for her postdoctoral contract. M.P.-E. acknowledges Junta de Castilla y León and European Social Found for his predoctoral contract. W.C. acknowledges Junta de Castilla y León for his postdoctoral fellowship (grant BU297P18) and funding received from the Marie Sklodowska-Curie postdoctoral fellowship (grant MSCA-IF-EF-ST 2020/101031622). J.V. P.-R. acknowledges Ministerio de Universidades and NextGenerationEU for his Maria Zambrano fellowship.

This dataset, "S4A-CyL," provides a comprehensive, multi-annual (2020-2024) collection of analysis-ready data patches for the Castilla y León region in Spain. It is specifically designed to support the development and validation of deep learning models for agricultural applications, with a primary focus on crop type classification. The dataset integrates dense Sentinel-2 L2A time series with meticulously processed agricultural parcel geometries and harmonized crop type labels derived from the Spanish Land Parcel Identification System (SIGPAC). A key feature is the implementation of a persistent parcel identification system, ensuring the temporal traceability of agricultural plots across the five-year period. The data is structured in a format inspired by the Sen4AgriNet project, with individual NetCDF files for each spatial patch. Each patch is a self-contained unit that includes the multi-spectral Sentinel-2 time series alongside the corresponding parcel ID and crop type reference layers., This work is part of the project: "Uso de imágenes Sentinel para la monitorización de prácticas agrícolas y su contribución a la iniciativa «4 por 1000» de incremento de carbono orgánico en el suelo" (TED2021-131638B-I00), from the "proyectos de transición ecológica y digital" (TED) program of 2021, funded by the Spanish Ministry of Science and Innovation, through the "Plan de recuperación, transformación y resiliencia" of the European Union.

The dataset contains all raw data of the work "Fast-Track Analysis of Beetroot Using the Liquid Generated During the Cooking Process", We gratefully acknowledge the financial support provided by all funders. The financial support provided by Fondo Europeo de Desarrollo Regional-European Regional Development Fund (FEDER, ERDF) and Regional Government of Castilla y León -Consejería de Educación, Junta de Castilla y León- (BU025P23) is gratefully acknowledged. This work was supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union NextGenerationEU PRTR. Author Saul Vallejos received grant BG22/00086 funded by Spanish Ministerio de Universidades. We also acknowledge the financial support provided by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe” (grant PID2023-147301OB-I00).

Bidimensional spectroelectrochemistry (Bidim-SEC) is an instrumental technique that provides operando UV/vis absorption information on electrochemical processes from two different points of view, using concomitantly a parallel and a normal optical configuration. The parallel configuration provides information about chemical species present in the diffusion layer, meanwhile the normal arrangement supplies information about changes occurring both in the diffusion layer and, mainly, on the electrode surface. The choice of a suitable cell to perform Bidim-SEC experiments is critical, especially while working under a thinlayer regime. So far, most of the proposed Bidim-SEC cells rely on the use of spacers to define the thin-layer thickness, which leads to working with constant thickness values. Herein, we propose a novel Bidim-SEC cell that enables easy-to-use micrometric control of the thin-layer thickness using a piezoelectric positioner. This device can be used for the study of complex interfacial systems and also to easily measure the key parameters of an electrochemical process. As a proof of concept, the study of the roughening of a gold electrode in KCl medium is performed, identifying key steps in the passivation and nanoparticle generation on the gold surface., Open Access funding provided thanks to the CRUE-CSIC agreement with American Chemical Society (ACS). This work was funded by the Ministerio de Ciencia e Innovacio?n and Agencia Estatal de Investigacion (MCIN/AEI/10.13039/501100011033 and PID2020-113154RBC21), Ministerio de Ciencia, Innovacion y Universidades (RED2022-134120-T), and Junta de Castilla y Leon and European Regional Development Fund (Grant number: BU036P23). M.P.-E. acknowledges Junta de Castilla y León and European Social Fund for his postdoctoral contract (BU036P23). J.V.P.-R. acknowledges Ministerio de Universidades and NextGenerationEU for his Maria Zambrano Fellowship. S.H. acknowledges Junta de Castilla y León and European Social Fund for her postdoctoral contract.

Raman enhancing strategies, such as Surface-Enhance Raman scattering (SERS), are a key piece for the development of spectroscopic and analytical strategies based on Raman spectroscopy, due to the intrinsic low sensitivity of the Raman scattering. Some years ago, our group reported an unexpected Raman enhancement process observed during the electrochemical oxidation of metallic electrodes, named Electrochemical Oxidation Surface-Enhanced Raman scattering (EC-SOERS). This Raman enhancement phenomenon was recently explained as an interaction of the analyte and the SERS dielectric substrate promoted by a metal cation. The elucidation of the origin of this enhancement is now leading to the development of new Raman enhancing substrates, such as copper-based substrates. In this work, we present an overview of the use of copper electrodes as EC-SOERS substrates. The presented strategies allow the electrosynthesis of SERS-active CuI nanocrystals on a metallic copper surface, which provides Raman enhancement for a wide number of molecules. The influence of the electrochemical conditions and the structure of the studied molecules are discussed. The use of CuSCN nanocrystals is also explored as substrates to promote Raman enhancement., Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier B.V. Ministerio de Ciencia e Innovacion and Agencia Estatal de Investigacion (MCIN/AEI/10.13039/501100011033, PID2020-113154RBC21), Junta de Castilla y Leon and European Regional Development Fund (Grant number: BU036P23), Ministerio de Ciencia, Innovacion y Universidades (RED2022-134120-T) are gratefully acknowledged for funding this work. M.P.-E. acknowledges Junta de Castilla y Leon and European Social Found for his predoctoral contract. W.Ch. acknowledges Junta de Castilla y Leon for his postdoctoral fellowship (Grant BU297P18) and funding received from Marie Sklodowska-Curie postdoctoral fellowship (Grant MSCA-IF-EF-ST 2020/101031622).

This study presents a novel electrochemical (EC) methodology for activating the SERS features of disposable silver screen-printed electrodes (AgSPEs) using a pseudohalide as a precipitating agent to guide the assembly of a nano-filamentous silver network responsible for a strong SERS enhancement. To the best of our knowledge, the use of thiocyanate for SPEs activation for quantitative purposes has not been reported before. In order to better study this complex system, time-resolved (TR) operando spectroelectrochemistry (SEC) measurements were performed by SERS and UV-Vis and correlated with SEM imaging of the electrode surface at different steps. Moreover, to significantly increase the reproducibility of the assays, a rapid EC protocol was proposed for the first time to obtain a reliable Ag/AgSCN reference electrode (RE) and a comprehensive optimization process was conducted to determine the critical parameters. Additionally, propranolol, as an emerging pharmaceutical pollutant has been selected as a model molecule to demonstrate the applicability of the method for rapid (3 min) quantitative analysis in the nM range from real river and tap water samples., Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier B.V. Ministerio de Ciencia e Innovacion and Agencia Estatal de Investigacion (MCIN/AEI/10.13039/501100011033, PID2020-113154RBC21), Ministerio de Ciencia, Innovacion y Universidades (RED2022-134120-T). M. P.-E. acknowledges Junta de Castilla y Leon and European Social Found for his predoctoral contract.

Background: The availability of new surface enhanced Raman scattering (SERS) substrates is essential to develop quantitative analytical methods. Electrochemistry is an easy, fast and reproducible methodology to prepare SERS substrates on screen-printed electrodes (SPEs). Results: This work proposes new SPEs based on a three-electrode system all made of silver. Using the same ink for the whole electrode system facilitates the fabrication process, reduces production costs, and leads to excellent analytical performance. The results showed that Raman enhancement depends strongly on the type of silver ink. To demonstrate the capabilities of the new electrodes developed, 4-aminosalicylic acid was determined in complex matrices and in the presence of strong interfering compounds such as salicylic acid and acetylsalicylic acid. The proposed analytical method is based on the electrochemical surface oxidation enhanced Raman scattering (EC-SOERS) strategy. AgCl nanocrystals are generated on the working electrode surface, which amplify the Raman signal of 4-aminosalicylic acid. Good figures of merit were obtained both in the absence and in the presence of the interfering compounds, achieving a correct estimation of a 4-aminosalicylic test sample in complex matrices. Significance: The new SPEs have been demonstrated to be very sensitive and reproducible which, together to the high specificity of the Raman signal, makes this methodology very attractive for chemical analysis., Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier B.V. Ministerio de Ciencia e Innovaci´on and Agencia Estatal de Investigacion (MCIN/AEI/10.13039/501100011033, PID2020-113154RB- C21, PID2020-113154RB-C22), Junta de Castilla y Leon and European Regional Development Fund (Grant number: BU036P23), Ministerio de Ciencia, Innovacion y Universidades (RED2022-134120-T) are fully acknowledged for funding this work. L.R. acknowledges Ministerio de Ciencia e Innovacion and Agencia Estatal de Investigacion (MCIN/ AEI/10.13039/501100011033, PIS2020-113154 GB-C21) for the doctoral contract. J.V. P.-R. acknowledges Ministerio de Universidades and NextGenerationEU for his Maria Zambrano fellowship.

Analytical Chemistry is the science of chemical measurements that seeks to acquire the most comprehensive information about a chemical system. Recent advances in technology have facilitated the development of new combined analytical techniques capable of supplying analytical signals of different natures. These signals subsequently provide diverse information related to specific chemical reactions. This technical note proposes a new combination of three different spectroscopic techniques (UV/vis absorption spectroscopy in a parallel configuration, photoluminescence and Raman spectroscopy) with electrochemistry. To illustrate the capabilities of this new technique, two chemical systems (tris(2,2' bipyridine)ruthenium(II) and ofloxacin) were selected. A comparison of the behavior of the two molecules during the electrode process demonstrates the advantages of obtaining several signals simultaneously in a single experiment., Open Access funding provided thanks to the CRUE-CSIC agreement with American Chemical Society (ACS). Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación MCIN/AEI/10.13039/501100011033 and FEDER, UE (Grant numbers: PID2020-113154RB-C21, PID2020-113154RB-C22, PID2023-149188OB-I00, RED2022-134120-T, RED2024-153970-T), Junta de Castilla y León and European Regional Development Fund (Grant number: BU036P23) are gratefully acknowledged for funding this work. F.O. acknowledges Junta de Castilla y León and the European Social Fund for her postdoctoral contract. M.P.-E. acknowledges Junta de Castilla y León and the European Social Fund for his postdoctoral contract.

Quantitative methods using surface-enhanced Raman scattering (SERS) for analysis in complex matrices are very attractive due to the high sensitivity and selectivity of this technique. In this work, a novel time-resolved electrochemical surface-enhanced Raman scattering (TR-EC-SERS) analytical method has been developed for the determination of nicotine in e-liquids of electronic cigarettes. One of the main challenges of SERS is its inherent lack of reproducibility. Here, this limitation was mitigated by employing an electrochemical pre-treatment step to generate a homogeneous distribution of silver nanoparticles (Ag-NPs) on a silver screen-printed electrode. The enhanced Raman scattering induced by the Ag-NPs enabled the detection of nicotine at nanomolar levels. The high sensitivity of the method allowed the quantitative analysis of diluted e-liquid samples, mitigating potential interferences from other components present in these complex matrices. Moreover, TR-EC-SERS, coupled with parallel factor analysis (PARAFAC), demonstrated the capability of trilinear spectroelectrochemistry data not only to detect nicotine but also to identify potential interfering compounds without prior knowledge of their spectral signatures. This multivariate approach offers significant potential for the detection of outliers in complex samples., Open Access funding provided thanks to the CRUE-CSIC agreement withElsevier B.V. Ministerio de Ciencia e Innovacion and Agencia Estatal de Investigacion (MCIN/AEI/10.13039/501100011033, PID2020-113154RB- C21, PID2023-149188OB-I00) and FEDER, UE, Junta de Castilla y Leon and European Regional Development Fund (Grant number: BU036P23), Ministerio de Ciencia, Innovacion y Universidades (RED2022-134120-T) are gratefully acknowledged for funding this work. L.R. acknowledges Ministerio de Ciencia e Innovacion and Agencia Estatal de Investigacion (MCIN/AEI/ 10.13039/ 501100011033, PIS2020-113154 GB-C21) for the predoctoral contract.