9 research outputs found
Glassy carbon electrode modified with 7,7,8,8-tetracyanoquinodimethane and graphene oxide triggered a synergistic effect: low-potential amperometric detection of reduced glutathione.
A sensitive electrochemical sensor based on the synergistic effect of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and graphene oxide (GO) for low-potential amperometric detection of reduced glutathione (GSH) in pH 7.2 phosphate buffer solution (PBS) has been reported. This is the first time that the combination of GO and TCNQ have been successfully employed to construct an electrochemical sensor for the detection of glutathione. The surface of the glassy carbon electrode (GCE) was modified by a drop casting using TCNQ and GO. Cyclic voltammetric measurements showed that TCNQ and GO triggered a synergistic effect and exhibited an unexpected electrocatalytic activity towards GSH oxidation, compared to GCE modified with only GO, TCNQ or TCNQ/electrochemically reduced GO. Three oxidation waves for GSH were found at −0.05, 0.1 and 0.5 V, respectively. Amperometric techniques were employed to detect GSH sensitively using a GCE modified with TCNQ/GO at −0.05 V. The electrochemical sensor showed a wide linear range from 0.25 to 124.3 μM and 124.3 μM to 1.67 mM with a limit of detection of 0.15 μM. The electroanalytical sensor was successfully applied towards the detection of GSH in an eye drop solution
The spontaneous symmetry breaking in TaNiSe is structural in nature
The excitonic insulator is an electronically-driven phase of matter that
emerges upon the spontaneous formation and Bose condensation of excitons.
Detecting this exotic order in candidate materials is a subject of paramount
importance, as the size of the excitonic gap in the band structure establishes
the potential of this collective state for superfluid energy transport.
However, the identification of this phase in real solids is hindered by the
coexistence of a structural order parameter with the same symmetry as the
excitonic order. Only a few materials are currently believed to host a dominant
excitonic phase, TaNiSe being the most promising. Here, we test this
scenario by using an ultrashort laser pulse to quench the broken-symmetry phase
of this transition metal chalcogenide. Tracking the dynamics of the material's
electronic and crystal structure after light excitation reveals surprising
spectroscopic fingerprints that are only compatible with a primary order
parameter of phononic nature. We rationalize our findings through
state-of-the-art calculations, confirming that the structural order accounts
for most of the electronic gap opening. Not only do our results uncover the
long-sought mechanism driving the phase transition of TaNiSe, but they
also conclusively rule out any substantial excitonic character in this
instability
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The spontaneous symmetry breaking in TaNiSe is structural in nature
The excitonic insulator is an electronically-driven phase of matter that
emerges upon the spontaneous formation and Bose condensation of excitons.
Detecting this exotic order in candidate materials is a subject of paramount
importance, as the size of the excitonic gap in the band structure establishes
the potential of this collective state for superfluid energy transport.
However, the identification of this phase in real solids is hindered by the
coexistence of a structural order parameter with the same symmetry as the
excitonic order. Only a few materials are currently believed to host a dominant
excitonic phase, TaNiSe being the most promising. Here, we test this
scenario by using an ultrashort laser pulse to quench the broken-symmetry phase
of this transition metal chalcogenide. Tracking the dynamics of the material's
electronic and crystal structure after light excitation reveals surprising
spectroscopic fingerprints that are only compatible with a primary order
parameter of phononic nature. We rationalize our findings through
state-of-the-art calculations, confirming that the structural order accounts
for most of the electronic gap opening. Not only do our results uncover the
long-sought mechanism driving the phase transition of TaNiSe, but they
also conclusively rule out any substantial excitonic character in this
instability