ORCID Profile
0000-0002-1221-3906
Current Organisations
KTH Royal Institute of Technology
,
Kungliga Tekniska Högskolan
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Publisher: Wiley
Date: 08-11-2019
Abstract: Water‐splitting photoanodes based on semiconductor materials typically require a dopant in the structure and co‐catalysts on the surface to overcome the problems of charge recombination and high catalytic barrier. Unlike these conventional strategies, a simple treatment is reported that involves soaking a s le of pristine BiVO 4 in a borate buffer solution. This modifies the catalytic local environment of BiVO 4 by the introduction of a borate moiety at the molecular level. The self‐anchored borate plays the role of a passivator in reducing the surface charge recombination as well as that of a ligand in modifying the catalytic site to facilitate faster water oxidation. The modified BiVO 4 photoanode, without typical doping or catalyst modification, achieved a photocurrent density of 3.5 mA cm −2 at 1.23 V and a cathodically shifted onset potential of 250 mV. This work provides an extremely simple method to improve the intrinsic photoelectrochemical performance of BiVO 4 photoanodes.
Publisher: American Chemical Society (ACS)
Date: 22-05-2017
Publisher: American Chemical Society (ACS)
Date: 27-02-2017
DOI: 10.1021/ACS.ANALCHEM.6B04625
Abstract: To understand the rate determining processes during the equilibration of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate-based (PEDOT(PSS)-based) solid contact (SC) ion-selective electrodes (ISEs), the surfaces of Pt, Au, and GC electrodes were coated with 0.1, 1.0, 2.0, and 4.0 μm thick galvanostatically deposited PEDOT(PSS) films. Next, potential vs time transients were recorded with these electrodes, with and without an additional potassium ion-selective membrane (ISM) coating, following their first contact with 0.1 M KCl solutions. The transients were significantly different when the multilayered sensor structures were assembled on Au or GC compared to Pt. The differences in the rate of equilibration were interpreted as a consequence of differences in the hydrophilicity of PEDOT(PSS) in contact with the substrate electrode surfaces based on X-ray photoelectron spectroscopy (XPS) and synchrotron radiation-XPS (SR-XPS) analysis of 10-100 nm thick PEDOT(PSS) films. The influence of the layer thickness of the electrochemically deposited PEDOT(PSS)-films on the hydrophilicity of these films has been documented by contact angle measurements over PEDOT(PSS)-coated Au, GC, and Pt electrode surfaces. This study demonstrates that it is possible to minimize the equilibration (conditioning) time of SC ISEs with aqueous solutions before usage by optimizing the thickness of the SC layer with a controlled ISM thickness. PEDOT(PSS)-coated Au and GC electrodes exhibit a significant negative potential drift during their equilibration in an aqueous solution. By coating the PEDOT(PSS) surface with an ISM, the negative potential drift is compensated by a positive potential drift related to the hydration of the ISM and activity changes at the PEDOT(PSS)|ISM interface. The potential drifts related to activity changes in the ISM have been determined by a novel adaptation of the "sandwich membrane" method.
Publisher: American Chemical Society (ACS)
Date: 15-06-2019
Publisher: American Chemical Society (ACS)
Date: 08-03-2018
DOI: 10.1021/ACS.ANALCHEM.7B05299
Abstract: A new submersible probe for the in situ detection of nitrate, nitrite, and chloride in seawater is presented. Inline coupling of a desalination unit, an acidification unit, and a sensing flow cell containing all-solid-state membrane electrodes allows for the potentiometric detection of nitrate and nitrite after removal of the key interfering ions in seawater, chloride and hydroxide. Thus, the electrodes exhibited attractive analytical performances for the potentiometric detection of nitrate and nitrite in desalinated and acidified seawater: fast response time ( t
Publisher: Elsevier BV
Date: 04-2021
Publisher: American Chemical Society (ACS)
Date: 28-09-2017
Publisher: American Chemical Society (ACS)
Date: 06-11-2019
DOI: 10.1021/ACS.ANALCHEM.9B03402
Abstract: Here, we provide the first experimental evidence of proton release from polyaniline (PANI) films subjected to anodic potentials at environmental pHs. We conducted an extensive characterization of unpolarized olarized PANI films-synthesized by traditional sequential voltammetric scanning-by using spectroelectrochemistry, synchrotron radiation-X-ray photoelectron spectroscopy, near edge X-ray absorption fine structure, and potentiometric pH sensing in the vicinity of the PANI layer. This new insight enables the utilization of PANI as a proton pump, which is actively tuned through an electrochemical pulse, so as to controllably acidify well-confined thin layer s les. Furthermore, we demonstrate the analytical significance of this system by measuring the alkalinity of artificial and natural water s les by using two faced planar PANI electrodes, one working as a proton source and the other one as pH electrode. Finally, the impact of this approach is 2-fold: (i) all-solid-state electrode materials may be used with devisible consequences in miniaturized and implementable submersible probes, and (ii) rapid determination of alkalinity as compared to traditional approaches together with a versatility in pH adjustment in any kind of s le, among other applications.
Publisher: Wiley
Date: 08-11-2019
Abstract: Water‐splitting photoanodes based on semiconductor materials typically require a dopant in the structure and co‐catalysts on the surface to overcome the problems of charge recombination and high catalytic barrier. Unlike these conventional strategies, a simple treatment is reported that involves soaking a s le of pristine BiVO 4 in a borate buffer solution. This modifies the catalytic local environment of BiVO 4 by the introduction of a borate moiety at the molecular level. The self‐anchored borate plays the role of a passivator in reducing the surface charge recombination as well as that of a ligand in modifying the catalytic site to facilitate faster water oxidation. The modified BiVO 4 photoanode, without typical doping or catalyst modification, achieved a photocurrent density of 3.5 mA cm −2 at 1.23 V and a cathodically shifted onset potential of 250 mV. This work provides an extremely simple method to improve the intrinsic photoelectrochemical performance of BiVO 4 photoanodes.
Publisher: MDPI AG
Date: 21-07-2020
DOI: 10.3390/S20144049
Abstract: Glycine monitoring is gaining importance as a biomarker in clinical analysis due to its involvement in multiple physiological functions, which results in glycine being one of the most analyzed biomolecules for diagnostics. This growing demand requires faster and more reliable, while affordable, analytical methods that can replace the current gold standard for glycine detection, which is based on s le extraction with subsequent use of liquid chromatography or fluorometric kits for its quantification in centralized laboratories. This work discusses electrochemical sensors and biosensors as an alternative option, focusing on their potential application for glycine determination in blood, urine, and cerebrospinal fluid, the three most widely used matrices for glycine analysis with clinical meaning. For electrochemical sensors, voltammetry/ erometry is the preferred readout (10 of the 13 papers collected in this review) and metal-based redox mediator modification is the predominant approach for electrode fabrication (11 of the 13 papers). However, none of the reported electrochemical sensors fulfill the requirements for direct analysis of biological fluids, most of them lacking appropriate selectivity, linear range of response, and/or capability of measuring at physiological conditions. Enhanced selectivity has been recently reported using biosensors (with an enzyme element in the electrode design), although this is still a very incipient approach. Currently, despite the benefits of electrochemistry, only optical biosensors have been successfully reported for glycine detection and, from all the inspected works, it is clear that bioengineering efforts will play a key role in the embellishment of selectivity and storage stability of the sensing element in the sensor.
Publisher: American Chemical Society (ACS)
Date: 10-02-2021
No related grants have been discovered for Gaston A. Crespo.