3 research outputs found
High-Resolution Analysis of Photoanodes for Water Splitting by Means of Scanning Photoelectrochemical Microscopy
In
pursuance of efficient tools for the local analysis and characterization
of novel photoelectrocatalytic materials, several SECM-based techniques
have been developed, aiming on the combined benefit of a local irradiation
of the analyzed sample and a microelectrode probe for the localized
electrochemical analysis of the surface. We present the development
and application of scanning photoelectrochemical microscopy (SPECM)
for the laterally resolved characterization of photoelectrocatalytic
materials. Particularly, the system was developed for the photoelectrochemical
characterization of n-type semiconductor-based photoanodes for water
splitting. By using the tip microelectrode simultaneously for local
irradiation and as an electrochemical probe, SPECM was capable to
simultaneously provide information about the local photocurrent generated
at the sample under irradiation and to detect the photoelectrocatalytically
evolved oxygen at the microelectrode. In combination with a novel
means of irradiation of the interrogated sample, local analysis of
semiconductor materials for light-induced water splitting with improved
lateral resolution is achieved
In Operando Investigation of Electrical Coupling of Photosystem 1 and Photosystem 2 by Means of Bipolar Electrochemistry
Electrochemical
communication between two photobioelectrochemical
half-cells based on photosystem 1 and photosystem 2 is investigated
in operando. The driving force for the electron-transfer reactions
is applied in a wireless mode using bipolar electrochemistry with
the actual electrode potentials being self-regulated by the redox
processes. Four parameters are assessed to understand the overall
performance and elucidate the limiting reactions of the photobioelectrochemical
cell. In addition to the potential differences for oxidation and reduction
reactions, the current flowing between the half-cells as well as in
situ collection of locally evolved O<sub>2</sub> by photosystem 2
using a positioned scanning electrochemical microscopy tip are evaluated.
In this way, changes in the enzymatic performances as a result of
inactivation of either of the protein complexes or variations in the
external conditions are monitored
Integrated Amperometric Affinity Biosensors Using Co<sup>2+</sup>āTetradentate Nitrilotriacetic Acid Modified Disposable Carbon Electrodes: Application to the Determination of Ī²āLactam Antibiotics
A novel strategy for the construction
of disposable amperometric
affinity biosensors is described in this work. The approach uses a
recombinant bacterial penicillin binding protein (PBP) tagged by an
N-terminal hexahistidine tail which was immobilized onto Co<sup>2+</sup>ātetradentate nitrilotriacetic acid (NTA)-modified screen-printed
carbon electrodes (SPCEs). The biosensor was employed for the specific
detection and quantification of Ī²-lactam antibiotics residues
in milk, which was accomplished by means of a direct competitive assay
using a tracer with horseradish peroxidase (HRP) for the enzymatic
labeling. The amperometric response measured at ā0.20 V versus
the Ag pseudoreference electrode of the SPCE upon the addition of
H<sub>2</sub>O<sub>2</sub> in the presence of hydroquinone (HQ) as
redox mediator was used as the transduction signal. The developed
affinity sensor allowed limits of detection to be obtained in the
low part-per-billion level for the antibiotics tested in untreated
milk samples. Moreover, the biosensor exhibited a good selectivity
against other antibiotics residues frequently detected in milk and
dairy products. The analysis time was of approximately 30 min